From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B52D8C197A0 for ; Mon, 20 Nov 2023 17:47:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233064AbjKTRrf (ORCPT ); Mon, 20 Nov 2023 12:47:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232359AbjKTRrc (ORCPT ); Mon, 20 Nov 2023 12:47:32 -0500 Received: from out-189.mta1.migadu.com (out-189.mta1.migadu.com [IPv6:2001:41d0:203:375::bd]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FB29BA for ; Mon, 20 Nov 2023 09:47:29 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502447; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9mwqfN/pqk9HRQ931HoPPP333OlumxbY++YPCTeY76U=; b=bR/I30d5ng/lYBtNQqgdoGfH5paO2CtcP21wojJGbtHFG33q9OSF6VODY4kRaiORiokLQo iZpd9D4Xa29yBgsAA1WjhOAcCg0lSOCGSH3njrApHXcLDY08VxXeaX0yqJ6yzjAbR1DXy7 0Hwm3iz+UTEkMpPA3RFCPkvRL0wjaJM= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 01/22] lib/stackdepot: print disabled message only if truly disabled Date: Mon, 20 Nov 2023 18:46:59 +0100 Message-Id: <73a25c5fff29f3357cd7a9330e85e09bc8da2cbe.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Currently, if stack_depot_disable=3Doff is passed to the kernel command-line after stack_depot_disable=3Don, stack depot prints a message that it is disabled, while it is actually enabled. Fix this by moving printing the disabled message to stack_depot_early_init. Place it before the __stack_depot_early_init_requested check, so that the message is printed even if early stack depot init has not been requested. Also drop the stack_table =3D NULL assignment from disable_stack_depot, as stack_table is NULL by default. Fixes: e1fdc403349c ("lib: stackdepot: add support to disable stack depot") Reviewed-by: Marco Elver Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- lib/stackdepot.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 2f5aa851834e..0eeaef4f2523 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -101,14 +101,7 @@ static int next_pool_required =3D 1; =20 static int __init disable_stack_depot(char *str) { - int ret; - - ret =3D kstrtobool(str, &stack_depot_disabled); - if (!ret && stack_depot_disabled) { - pr_info("disabled\n"); - stack_table =3D NULL; - } - return 0; + return kstrtobool(str, &stack_depot_disabled); } early_param("stack_depot_disable", disable_stack_depot); =20 @@ -130,6 +123,15 @@ int __init stack_depot_early_init(void) return 0; __stack_depot_early_init_passed =3D true; =20 + /* + * Print disabled message even if early init has not been requested: + * stack_depot_init() will not print one. + */ + if (stack_depot_disabled) { + pr_info("disabled\n"); + return 0; + } + /* * If KASAN is enabled, use the maximum order: KASAN is frequently used * in fuzzing scenarios, which leads to a large number of different @@ -138,7 +140,11 @@ int __init stack_depot_early_init(void) if (kasan_enabled() && !stack_bucket_number_order) stack_bucket_number_order =3D STACK_BUCKET_NUMBER_ORDER_MAX; =20 - if (!__stack_depot_early_init_requested || stack_depot_disabled) + /* + * Check if early init has been requested after setting + * stack_bucket_number_order: stack_depot_init() uses its value. + */ + if (!__stack_depot_early_init_requested) return 0; =20 /* --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5A60C197A0 for ; Mon, 20 Nov 2023 17:47:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233885AbjKTRrl (ORCPT ); Mon, 20 Nov 2023 12:47:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51254 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232547AbjKTRrd (ORCPT ); Mon, 20 Nov 2023 12:47:33 -0500 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B871510E for ; Mon, 20 Nov 2023 09:47:29 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502447; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4GD92F9WT2lJ15sdFM57D7OnzHXCVz8Opyiuivl9/aY=; b=qyhdPL9yHGZwgbX97BEztXeCz1Zt+rIj3RmbbGcjPTQsTwh98G4ATjxhFfnwka3CKqD1b6 x9kwKDWmny/BO2cvVbgqEwg2/wpgt3BzZx3yBf1KxUz7o5wnkBkYXhX4a/sfMby5QWyf2c 4HelafeGlMBXbFW+ItTdiGsKvqfzEZg= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 02/22] lib/stackdepot: check disabled flag when fetching Date: Mon, 20 Nov 2023 18:47:00 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Do not try fetching a stack trace from the stack depot if the stack_depot_disabled flag is enabled. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- lib/stackdepot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 0eeaef4f2523..f8a8033e1dc8 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -483,7 +483,7 @@ unsigned int stack_depot_fetch(depot_stack_handle_t han= dle, */ kmsan_unpoison_memory(entries, sizeof(*entries)); =20 - if (!handle) + if (!handle || stack_depot_disabled) return 0; =20 if (parts.pool_index > pool_index_cached) { --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54E8DC2BB3F for ; Mon, 20 Nov 2023 17:47:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234007AbjKTRrn (ORCPT ); Mon, 20 Nov 2023 12:47:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232734AbjKTRrd (ORCPT ); Mon, 20 Nov 2023 12:47:33 -0500 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [IPv6:2001:41d0:203:375::ac]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E65411C for ; Mon, 20 Nov 2023 09:47:30 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502448; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VQKv8ipVyqmLqtwmF3tWarfk+ElO5xq6wgwn4qj22hY=; b=DpwTRKlGqKrBB4M8buYXFUbh5C4t1DeCOJCZmUpqezNSRGsyD+Wdylo613HdhfnrTQ5s+e pjLcUIFVsXiRTj7skGIcX0r4YxbEBcZF9ntx+1uASDYWt1MOFzRn7mamvzav2NVLFYw6Tg zTiWDgpYpFtnG/OSWJ9T8vQPvfnqvc0= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 03/22] lib/stackdepot: simplify __stack_depot_save Date: Mon, 20 Nov 2023 18:47:01 +0100 Message-Id: <3b0763c8057a1cf2f200ff250a5f9580ee36a28c.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov The retval local variable in __stack_depot_save has the union type handle_parts, but the function never uses anything but the union's handle field. Define retval simply as depot_stack_handle_t to simplify the code. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- lib/stackdepot.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index f8a8033e1dc8..3e71c8f61c7d 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -366,7 +366,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, gfp_t alloc_flags, bool can_alloc) { struct stack_record *found =3D NULL, **bucket; - union handle_parts retval =3D { .handle =3D 0 }; + depot_stack_handle_t handle =3D 0; struct page *page =3D NULL; void *prealloc =3D NULL; unsigned long flags; @@ -383,7 +383,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, nr_entries =3D filter_irq_stacks(entries, nr_entries); =20 if (unlikely(nr_entries =3D=3D 0) || stack_depot_disabled) - goto fast_exit; + return 0; =20 hash =3D hash_stack(entries, nr_entries); bucket =3D &stack_table[hash & stack_hash_mask]; @@ -449,9 +449,8 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, free_pages((unsigned long)prealloc, DEPOT_POOL_ORDER); } if (found) - retval.handle =3D found->handle.handle; -fast_exit: - return retval.handle; + handle =3D found->handle.handle; + return handle; } EXPORT_SYMBOL_GPL(__stack_depot_save); =20 --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92847C197A0 for ; Mon, 20 Nov 2023 17:47:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234087AbjKTRrq (ORCPT ); Mon, 20 Nov 2023 12:47:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232803AbjKTRre (ORCPT ); Mon, 20 Nov 2023 12:47:34 -0500 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D5D5BA for ; Mon, 20 Nov 2023 09:47:30 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502449; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lmg5zTuKt1w9oWZyNpXv7HY69NJCp78Dr+tP0crczmk=; b=sig9IVvlHqVaQ7yAjHcKyEBZSXKZVvVyW0FFm1WUvwt3/VhlR8ohBHYAlXrR7cabYtXtPi 1x7T5BIS3RF5oH+C0wW4PoHF0fJj3mAq0pXEuDuyXI6LIJomNt8wyDqJivUeLox2pQT6re fzBBmv3FWure1h0tN/rWvxM6gmS3lDg= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 04/22] lib/stackdepot: drop valid bit from handles Date: Mon, 20 Nov 2023 18:47:02 +0100 Message-Id: <34969bba2ca6e012c6ad071767197dee64dc5723.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Stack depot doesn't use the valid bit in handles in any way, so drop it. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- lib/stackdepot.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 3e71c8f61c7d..46a422d31c1f 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -32,13 +32,12 @@ =20 #define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8) =20 -#define DEPOT_VALID_BITS 1 #define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */ #define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER)) #define DEPOT_STACK_ALIGN 4 #define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALI= GN) -#define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_VALID_BITS - \ - DEPOT_OFFSET_BITS - STACK_DEPOT_EXTRA_BITS) +#define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_OFFSET_BITS - \ + STACK_DEPOT_EXTRA_BITS) #define DEPOT_POOLS_CAP 8192 #define DEPOT_MAX_POOLS \ (((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? \ @@ -50,7 +49,6 @@ union handle_parts { struct { u32 pool_index : DEPOT_POOL_INDEX_BITS; u32 offset : DEPOT_OFFSET_BITS; - u32 valid : DEPOT_VALID_BITS; u32 extra : STACK_DEPOT_EXTRA_BITS; }; }; @@ -309,7 +307,6 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) stack->size =3D size; stack->handle.pool_index =3D pool_index; stack->handle.offset =3D pool_offset >> DEPOT_STACK_ALIGN; - stack->handle.valid =3D 1; stack->handle.extra =3D 0; memcpy(stack->entries, entries, flex_array_size(stack, entries, size)); pool_offset +=3D required_size; --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 641C0C197A0 for ; Mon, 20 Nov 2023 17:47:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233804AbjKTRru (ORCPT ); Mon, 20 Nov 2023 12:47:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232999AbjKTRrf (ORCPT ); Mon, 20 Nov 2023 12:47:35 -0500 Received: from out-170.mta1.migadu.com (out-170.mta1.migadu.com [IPv6:2001:41d0:203:375::aa]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F70A9E for ; Mon, 20 Nov 2023 09:47:31 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502449; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4+Y9MGkz9f3yZSUENZCgBAvLs1CfO+kuipQPdiyYS+c=; b=Ql85St5SjYl9dK6UKQo/wZBfC05xwZ8kz2f2txy485DwN0EC3gx7bgEAGlRsR3amTQZM6i Nep6MT9W4kXFWBOfaYnIaeXGDBapToM5EgH6SXSUwG03GDKgl7MtqpodPgiSEzEwBXoD0L 1m7pwV0+V5c6VKCswrtvLTavWAO/Q/M= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 05/22] lib/stackdepot: add depot_fetch_stack helper Date: Mon, 20 Nov 2023 18:47:03 +0100 Message-Id: <170d8c202f29dc8e3d5491ee074d1e9e029a46db.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Add a helper depot_fetch_stack function that fetches the pointer to a stack record. With this change, all static depot_* functions now operate on stack pools and the exported stack_depot_* functions operate on the hash table. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- Changes v1->v2: - Minor comment fix as suggested by Alexander. --- lib/stackdepot.c | 45 ++++++++++++++++++++++++++++----------------- 1 file changed, 28 insertions(+), 17 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 46a422d31c1f..e41713983cac 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -310,6 +310,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) stack->handle.extra =3D 0; memcpy(stack->entries, entries, flex_array_size(stack, entries, size)); pool_offset +=3D required_size; + /* * Let KMSAN know the stored stack record is initialized. This shall * prevent false positive reports if instrumented code accesses it. @@ -319,6 +320,32 @@ depot_alloc_stack(unsigned long *entries, int size, u3= 2 hash, void **prealloc) return stack; } =20 +static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle) +{ + union handle_parts parts =3D { .handle =3D handle }; + /* + * READ_ONCE pairs with potential concurrent write in + * depot_alloc_stack(). + */ + int pool_index_cached =3D READ_ONCE(pool_index); + void *pool; + size_t offset =3D parts.offset << DEPOT_STACK_ALIGN; + struct stack_record *stack; + + if (parts.pool_index > pool_index_cached) { + WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", + parts.pool_index, pool_index_cached, handle); + return NULL; + } + + pool =3D stack_pools[parts.pool_index]; + if (!pool) + return NULL; + + stack =3D pool + offset; + return stack; +} + /* Calculates the hash for a stack. */ static inline u32 hash_stack(unsigned long *entries, unsigned int size) { @@ -462,14 +489,6 @@ EXPORT_SYMBOL_GPL(stack_depot_save); unsigned int stack_depot_fetch(depot_stack_handle_t handle, unsigned long **entries) { - union handle_parts parts =3D { .handle =3D handle }; - /* - * READ_ONCE pairs with potential concurrent write in - * depot_alloc_stack. - */ - int pool_index_cached =3D READ_ONCE(pool_index); - void *pool; - size_t offset =3D parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack; =20 *entries =3D NULL; @@ -482,15 +501,7 @@ unsigned int stack_depot_fetch(depot_stack_handle_t ha= ndle, if (!handle || stack_depot_disabled) return 0; =20 - if (parts.pool_index > pool_index_cached) { - WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", - parts.pool_index, pool_index_cached, handle); - return 0; - } - pool =3D stack_pools[parts.pool_index]; - if (!pool) - return 0; - stack =3D pool + offset; + stack =3D depot_fetch_stack(handle); =20 *entries =3D stack->entries; return stack->size; --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6351BC197A0 for ; Mon, 20 Nov 2023 17:49:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234062AbjKTRt3 (ORCPT ); Mon, 20 Nov 2023 12:49:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234106AbjKTRtR (ORCPT ); Mon, 20 Nov 2023 12:49:17 -0500 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [IPv6:2001:41d0:1004:224b::ad]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B743CD2 for ; Mon, 20 Nov 2023 09:48:34 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502512; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pu1XFZGC+3mxYm/tNoBY6t9qKRkAeXfQVUMTHQNQJK8=; b=v29OoaCrQAFVYXx8qE1accX78dCRXzOu4rgaHGTPoImCDsSRXsXJW7zty4lVMppXjkqcg3 cICBXUXycfKNBxolMNR9vSSUR3Qdi4ReyKaR9Gp00MSY7TEAkMubulEyKPVq2YOWSy/vMK Csf5CwyODxYj8dOCpaCpXMz38YUJonc= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 06/22] lib/stackdepot: use fixed-sized slots for stack records Date: Mon, 20 Nov 2023 18:47:04 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Instead of storing stack records in stack depot pools one right after another, use fixed-sized slots. Add a new Kconfig option STACKDEPOT_MAX_FRAMES that allows to select the size of the slot in frames. Use 64 as the default value, which is the maximum stack trace size both KASAN and KMSAN use right now. Also add descriptions for other stack depot Kconfig options. This is preparatory patch for implementing the eviction of stack records from the stack depot. Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- Changes v2->v3: - Keep previously existing Kconfig options not configurable by users. Changes v1->v2: - Add and use STACKDEPOT_MAX_FRAMES Kconfig option. --- lib/Kconfig | 10 ++++++++++ lib/stackdepot.c | 13 +++++++++---- 2 files changed, 19 insertions(+), 4 deletions(-) diff --git a/lib/Kconfig b/lib/Kconfig index 3ea1c830efab..5ddda7c2ed9b 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -713,10 +713,20 @@ config ARCH_STACKWALK config STACKDEPOT bool select STACKTRACE + help + Stack depot: stack trace storage that avoids duplication =20 config STACKDEPOT_ALWAYS_INIT bool select STACKDEPOT + help + Always initialize stack depot during early boot + +config STACKDEPOT_MAX_FRAMES + int "Maximum number of frames in trace saved in stack depot" + range 1 256 + default 64 + depends on STACKDEPOT =20 config REF_TRACKER bool diff --git a/lib/stackdepot.c b/lib/stackdepot.c index e41713983cac..682497dbe081 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -58,9 +58,12 @@ struct stack_record { u32 hash; /* Hash in the hash table */ u32 size; /* Number of stored frames */ union handle_parts handle; - unsigned long entries[]; /* Variable-sized array of frames */ + unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */ }; =20 +#define DEPOT_STACK_RECORD_SIZE \ + ALIGN(sizeof(struct stack_record), 1 << DEPOT_STACK_ALIGN) + static bool stack_depot_disabled; static bool __stack_depot_early_init_requested __initdata =3D IS_ENABLED(C= ONFIG_STACKDEPOT_ALWAYS_INIT); static bool __stack_depot_early_init_passed __initdata; @@ -264,9 +267,7 @@ static struct stack_record * depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **preal= loc) { struct stack_record *stack; - size_t required_size =3D struct_size(stack, entries, size); - - required_size =3D ALIGN(required_size, 1 << DEPOT_STACK_ALIGN); + size_t required_size =3D DEPOT_STACK_RECORD_SIZE; =20 /* Check if there is not enough space in the current pool. */ if (unlikely(pool_offset + required_size > DEPOT_POOL_SIZE)) { @@ -301,6 +302,10 @@ depot_alloc_stack(unsigned long *entries, int size, u3= 2 hash, void **prealloc) if (stack_pools[pool_index] =3D=3D NULL) return NULL; =20 + /* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */ + if (size > CONFIG_STACKDEPOT_MAX_FRAMES) + size =3D CONFIG_STACKDEPOT_MAX_FRAMES; + /* Save the stack trace. */ stack =3D stack_pools[pool_index] + pool_offset; stack->hash =3D hash; --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DDB2FC197A0 for ; Mon, 20 Nov 2023 17:49:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234157AbjKTRtd (ORCPT ); Mon, 20 Nov 2023 12:49:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234159AbjKTRtR (ORCPT ); Mon, 20 Nov 2023 12:49:17 -0500 Received: from out-176.mta0.migadu.com (out-176.mta0.migadu.com [IPv6:2001:41d0:1004:224b::b0]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E83C9D5B for ; Mon, 20 Nov 2023 09:48:34 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502513; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ul/nKw7kj0oOeSlF9NlnEwH7YAqJQYzQqOqaJ7LWVgY=; b=ukcrau9rBSSL43tgTPUpFjw/XmDDuuV7b5Rf6ugJdDIx3eaVAx8V/9PFiPuIgxA8HOVqDI FOv6Ks7qLmHGEak24eJMUo0HQta3weJK4BNrKPY6LbsCGCWMiUh2CgVaukTzBdLG8nj0JF 0fqdYiwEAxqEdM4YGbvK075MNLH3F5M= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 07/22] lib/stackdepot: fix and clean-up atomic annotations Date: Mon, 20 Nov 2023 18:47:05 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Drop smp_load_acquire from next_pool_required in depot_init_pool, as both depot_init_pool and the all smp_store_release's to this variable are executed under the stack depot lock. Also simplify and clean up comments accompanying the use of atomic accesses in the stack depot code. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- This patch is not strictly required, as the atomic accesses are fully removed in one of the latter patches. However, I decided to keep the patch just in case we end up needing these atomics in the following iterations of this series. Changes v2->v3: - Keep parentheses when referring to functions in comments. - Add comment that explains why depot_init_pool reads next_pool_required non-atomically. Changes v1->v2: - Minor comment fix as suggested by Marco. - Drop READ_ONCE marking for next_pool_required. --- lib/stackdepot.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 682497dbe081..cfa3c6c7cc2e 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -231,10 +231,10 @@ static void depot_init_pool(void **prealloc) /* * If the next pool is already initialized or the maximum number of * pools is reached, do not use the preallocated memory. - * smp_load_acquire() here pairs with smp_store_release() below and - * in depot_alloc_stack(). + * Access next_pool_required non-atomically, as there are no concurrent + * write accesses to this variable. */ - if (!smp_load_acquire(&next_pool_required)) + if (!next_pool_required) return; =20 /* Check if the current pool is not yet allocated. */ @@ -255,8 +255,8 @@ static void depot_init_pool(void **prealloc) * At this point, either the next pool is initialized or the * maximum number of pools is reached. In either case, take * note that initializing another pool is not required. - * This smp_store_release pairs with smp_load_acquire() above - * and in stack_depot_save(). + * smp_store_release() pairs with smp_load_acquire() in + * stack_depot_save(). */ smp_store_release(&next_pool_required, 0); } @@ -279,7 +279,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) =20 /* * Move on to the next pool. - * WRITE_ONCE pairs with potential concurrent read in + * WRITE_ONCE() pairs with potential concurrent read in * stack_depot_fetch(). */ WRITE_ONCE(pool_index, pool_index + 1); @@ -287,8 +287,8 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) /* * If the maximum number of pools is not reached, take note * that the next pool needs to initialized. - * smp_store_release() here pairs with smp_load_acquire() in - * stack_depot_save() and depot_init_pool(). + * smp_store_release() pairs with smp_load_acquire() in + * stack_depot_save(). */ if (pool_index + 1 < DEPOT_MAX_POOLS) smp_store_release(&next_pool_required, 1); @@ -329,7 +329,7 @@ static struct stack_record *depot_fetch_stack(depot_sta= ck_handle_t handle) { union handle_parts parts =3D { .handle =3D handle }; /* - * READ_ONCE pairs with potential concurrent write in + * READ_ONCE() pairs with potential concurrent write in * depot_alloc_stack(). */ int pool_index_cached =3D READ_ONCE(pool_index); @@ -419,8 +419,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, =20 /* * Fast path: look the stack trace up without locking. - * The smp_load_acquire() here pairs with smp_store_release() to - * |bucket| below. + * smp_load_acquire() pairs with smp_store_release() to |bucket| below. */ found =3D find_stack(smp_load_acquire(bucket), entries, nr_entries, hash); if (found) @@ -430,8 +429,8 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, * Check if another stack pool needs to be initialized. If so, allocate * the memory now - we won't be able to do that under the lock. * - * The smp_load_acquire() here pairs with smp_store_release() to - * |next_pool_inited| in depot_alloc_stack() and depot_init_pool(). + * smp_load_acquire() pairs with smp_store_release() in + * depot_alloc_stack() and depot_init_pool(). */ if (unlikely(can_alloc && smp_load_acquire(&next_pool_required))) { /* @@ -457,8 +456,8 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, if (new) { new->next =3D *bucket; /* - * This smp_store_release() pairs with - * smp_load_acquire() from |bucket| above. + * smp_store_release() pairs with smp_load_acquire() + * from |bucket| above. */ smp_store_release(bucket, new); found =3D new; --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D4BFC197A0 for ; Mon, 20 Nov 2023 17:49:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233626AbjKTRtf (ORCPT ); Mon, 20 Nov 2023 12:49:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234496AbjKTRtR (ORCPT ); Mon, 20 Nov 2023 12:49:17 -0500 Received: from out-181.mta0.migadu.com (out-181.mta0.migadu.com [IPv6:2001:41d0:1004:224b::b5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 757AA12A for ; Mon, 20 Nov 2023 09:48:35 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502513; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9IYHxZGEq/qB2Qlddv235LQK4ccHh5XyxORYKM2z5Wc=; b=Kt5p6zScvUKaXsHar2QlUefWEFtJ6Uws7kbkfGgrB5cxpVMGSn2WXhKYFJ5MhB50RhntDQ K7N0E2IbssHoPp6AeWgnF1sPLT3aDEF/nGgRuJ546AoCXVl6clQWGAmNHZLEBxlZNtF5g9 xiIqlvFkZnYs+J6Hza0Jtp/FsRG4z5s= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 08/22] lib/stackdepot: rework helpers for depot_alloc_stack Date: Mon, 20 Nov 2023 18:47:06 +0100 Message-Id: <71fb144d42b701fcb46708d7f4be6801a4a8270e.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Split code in depot_alloc_stack and depot_init_pool into 3 functions: 1. depot_keep_next_pool that keeps preallocated memory for the next pool if required. 2. depot_update_pools that moves on to the next pool if there's no space left in the current pool, uses preallocated memory for the new current pool if required, and calls depot_keep_next_pool otherwise. 3. depot_alloc_stack that calls depot_update_pools and then allocates a stack record as before. This makes it somewhat easier to follow the logic of depot_alloc_stack and also serves as a preparation for implementing the eviction of stack records from the stack depot. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- Changes v2->v3: - Add parentheses when referring to function calls in comments. --- lib/stackdepot.c | 86 +++++++++++++++++++++++++++--------------------- 1 file changed, 49 insertions(+), 37 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index cfa3c6c7cc2e..b3af868627f4 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -225,11 +225,11 @@ int stack_depot_init(void) } EXPORT_SYMBOL_GPL(stack_depot_init); =20 -/* Uses preallocated memory to initialize a new stack depot pool. */ -static void depot_init_pool(void **prealloc) +/* Keeps the preallocated memory to be used for the next stack depot pool.= */ +static void depot_keep_next_pool(void **prealloc) { /* - * If the next pool is already initialized or the maximum number of + * If the next pool is already saved or the maximum number of * pools is reached, do not use the preallocated memory. * Access next_pool_required non-atomically, as there are no concurrent * write accesses to this variable. @@ -237,44 +237,34 @@ static void depot_init_pool(void **prealloc) if (!next_pool_required) return; =20 - /* Check if the current pool is not yet allocated. */ - if (stack_pools[pool_index] =3D=3D NULL) { - /* Use the preallocated memory for the current pool. */ - stack_pools[pool_index] =3D *prealloc; + /* + * Use the preallocated memory for the next pool + * as long as we do not exceed the maximum number of pools. + */ + if (pool_index + 1 < DEPOT_MAX_POOLS) { + stack_pools[pool_index + 1] =3D *prealloc; *prealloc =3D NULL; - } else { - /* - * Otherwise, use the preallocated memory for the next pool - * as long as we do not exceed the maximum number of pools. - */ - if (pool_index + 1 < DEPOT_MAX_POOLS) { - stack_pools[pool_index + 1] =3D *prealloc; - *prealloc =3D NULL; - } - /* - * At this point, either the next pool is initialized or the - * maximum number of pools is reached. In either case, take - * note that initializing another pool is not required. - * smp_store_release() pairs with smp_load_acquire() in - * stack_depot_save(). - */ - smp_store_release(&next_pool_required, 0); } + + /* + * At this point, either the next pool is kept or the maximum + * number of pools is reached. In either case, take note that + * keeping another pool is not required. + * smp_store_release() pairs with smp_load_acquire() in + * stack_depot_save(). + */ + smp_store_release(&next_pool_required, 0); } =20 -/* Allocates a new stack in a stack depot pool. */ -static struct stack_record * -depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **preal= loc) +/* Updates references to the current and the next stack depot pools. */ +static bool depot_update_pools(size_t required_size, void **prealloc) { - struct stack_record *stack; - size_t required_size =3D DEPOT_STACK_RECORD_SIZE; - /* Check if there is not enough space in the current pool. */ if (unlikely(pool_offset + required_size > DEPOT_POOL_SIZE)) { /* Bail out if we reached the pool limit. */ if (unlikely(pool_index + 1 >=3D DEPOT_MAX_POOLS)) { WARN_ONCE(1, "Stack depot reached limit capacity"); - return NULL; + return false; } =20 /* @@ -284,9 +274,10 @@ depot_alloc_stack(unsigned long *entries, int size, u3= 2 hash, void **prealloc) */ WRITE_ONCE(pool_index, pool_index + 1); pool_offset =3D 0; + /* * If the maximum number of pools is not reached, take note - * that the next pool needs to initialized. + * that the next pool needs to be initialized. * smp_store_release() pairs with smp_load_acquire() in * stack_depot_save(). */ @@ -294,9 +285,30 @@ depot_alloc_stack(unsigned long *entries, int size, u3= 2 hash, void **prealloc) smp_store_release(&next_pool_required, 1); } =20 - /* Assign the preallocated memory to a pool if required. */ + /* Check if the current pool is not yet allocated. */ + if (*prealloc && stack_pools[pool_index] =3D=3D NULL) { + /* Use the preallocated memory for the current pool. */ + stack_pools[pool_index] =3D *prealloc; + *prealloc =3D NULL; + return true; + } + + /* Otherwise, try using the preallocated memory for the next pool. */ if (*prealloc) - depot_init_pool(prealloc); + depot_keep_next_pool(prealloc); + return true; +} + +/* Allocates a new stack in a stack depot pool. */ +static struct stack_record * +depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **preal= loc) +{ + struct stack_record *stack; + size_t required_size =3D DEPOT_STACK_RECORD_SIZE; + + /* Update current and next pools if required and possible. */ + if (!depot_update_pools(required_size, prealloc)) + return NULL; =20 /* Check if we have a pool to save the stack trace. */ if (stack_pools[pool_index] =3D=3D NULL) @@ -330,7 +342,7 @@ static struct stack_record *depot_fetch_stack(depot_sta= ck_handle_t handle) union handle_parts parts =3D { .handle =3D handle }; /* * READ_ONCE() pairs with potential concurrent write in - * depot_alloc_stack(). + * depot_update_pools(). */ int pool_index_cached =3D READ_ONCE(pool_index); void *pool; @@ -430,7 +442,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, * the memory now - we won't be able to do that under the lock. * * smp_load_acquire() pairs with smp_store_release() in - * depot_alloc_stack() and depot_init_pool(). + * depot_update_pools() and depot_keep_next_pool(). */ if (unlikely(can_alloc && smp_load_acquire(&next_pool_required))) { /* @@ -467,7 +479,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, * Stack depot already contains this stack trace, but let's * keep the preallocated memory for the future. */ - depot_init_pool(&prealloc); + depot_keep_next_pool(&prealloc); } =20 raw_spin_unlock_irqrestore(&pool_lock, flags); --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 99EAFC2BB3F for ; Mon, 20 Nov 2023 17:49:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234091AbjKTRti (ORCPT ); Mon, 20 Nov 2023 12:49:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234249AbjKTRtR (ORCPT ); Mon, 20 Nov 2023 12:49:17 -0500 Received: from out-176.mta0.migadu.com (out-176.mta0.migadu.com [IPv6:2001:41d0:1004:224b::b0]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D23AD77 for ; Mon, 20 Nov 2023 09:48:35 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502514; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hhwH9Rj+7SlwckI0c6mMcIkIslfacxpde7X6neQ7UWA=; b=tZ0IiLouwcQL+2MAJN48oud52EurhrFZ0EVdLm9w8bTgwIXFM6wmInvK6PvSCrc9NfsCH+ mZJSfVlEyctgDWkqrhpIIt5iHEnorbr/fJGIrTZlLY3MGFvfhwPt5aeKYygAHMY4xY+vIV lxaS4PU+oIsToSR3HDnVIiG5H7/UWHw= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 09/22] lib/stackdepot: rename next_pool_required to new_pool_required Date: Mon, 20 Nov 2023 18:47:07 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Rename next_pool_required to new_pool_required. This a purely code readability change: the following patch will change stack depot to store the pointer to the new pool in a separate variable, and "new" seems like a more logical name. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- lib/stackdepot.c | 49 ++++++++++++++++++++++++------------------------ 1 file changed, 24 insertions(+), 25 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index b3af868627f4..a38661beab97 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -93,12 +93,11 @@ static size_t pool_offset; static DEFINE_RAW_SPINLOCK(pool_lock); /* * Stack depot tries to keep an extra pool allocated even before it runs o= ut - * of space in the currently used pool. - * This flag marks that this next extra pool needs to be allocated and - * initialized. It has the value 0 when either the next pool is not yet - * initialized or the limit on the number of pools is reached. + * of space in the currently used pool. This flag marks whether this extra= pool + * needs to be allocated. It has the value 0 when either an extra pool is = not + * yet allocated or if the limit on the number of pools is reached. */ -static int next_pool_required =3D 1; +static int new_pool_required =3D 1; =20 static int __init disable_stack_depot(char *str) { @@ -225,20 +224,20 @@ int stack_depot_init(void) } EXPORT_SYMBOL_GPL(stack_depot_init); =20 -/* Keeps the preallocated memory to be used for the next stack depot pool.= */ -static void depot_keep_next_pool(void **prealloc) +/* Keeps the preallocated memory to be used for a new stack depot pool. */ +static void depot_keep_new_pool(void **prealloc) { /* - * If the next pool is already saved or the maximum number of + * If a new pool is already saved or the maximum number of * pools is reached, do not use the preallocated memory. - * Access next_pool_required non-atomically, as there are no concurrent + * Access new_pool_required non-atomically, as there are no concurrent * write accesses to this variable. */ - if (!next_pool_required) + if (!new_pool_required) return; =20 /* - * Use the preallocated memory for the next pool + * Use the preallocated memory for the new pool * as long as we do not exceed the maximum number of pools. */ if (pool_index + 1 < DEPOT_MAX_POOLS) { @@ -247,13 +246,13 @@ static void depot_keep_next_pool(void **prealloc) } =20 /* - * At this point, either the next pool is kept or the maximum + * At this point, either a new pool is kept or the maximum * number of pools is reached. In either case, take note that * keeping another pool is not required. * smp_store_release() pairs with smp_load_acquire() in * stack_depot_save(). */ - smp_store_release(&next_pool_required, 0); + smp_store_release(&new_pool_required, 0); } =20 /* Updates references to the current and the next stack depot pools. */ @@ -268,7 +267,7 @@ static bool depot_update_pools(size_t required_size, vo= id **prealloc) } =20 /* - * Move on to the next pool. + * Move on to the new pool. * WRITE_ONCE() pairs with potential concurrent read in * stack_depot_fetch(). */ @@ -277,12 +276,12 @@ static bool depot_update_pools(size_t required_size, = void **prealloc) =20 /* * If the maximum number of pools is not reached, take note - * that the next pool needs to be initialized. + * that yet another new pool needs to be allocated. * smp_store_release() pairs with smp_load_acquire() in * stack_depot_save(). */ if (pool_index + 1 < DEPOT_MAX_POOLS) - smp_store_release(&next_pool_required, 1); + smp_store_release(&new_pool_required, 1); } =20 /* Check if the current pool is not yet allocated. */ @@ -293,9 +292,9 @@ static bool depot_update_pools(size_t required_size, vo= id **prealloc) return true; } =20 - /* Otherwise, try using the preallocated memory for the next pool. */ + /* Otherwise, try using the preallocated memory for a new pool. */ if (*prealloc) - depot_keep_next_pool(prealloc); + depot_keep_new_pool(prealloc); return true; } =20 @@ -306,7 +305,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) struct stack_record *stack; size_t required_size =3D DEPOT_STACK_RECORD_SIZE; =20 - /* Update current and next pools if required and possible. */ + /* Update current and new pools if required and possible. */ if (!depot_update_pools(required_size, prealloc)) return NULL; =20 @@ -438,13 +437,13 @@ depot_stack_handle_t __stack_depot_save(unsigned long= *entries, goto exit; =20 /* - * Check if another stack pool needs to be initialized. If so, allocate - * the memory now - we won't be able to do that under the lock. + * Check if another stack pool needs to be allocated. If so, allocate + * the memory now: we won't be able to do that under the lock. * * smp_load_acquire() pairs with smp_store_release() in - * depot_update_pools() and depot_keep_next_pool(). + * depot_update_pools() and depot_keep_new_pool(). */ - if (unlikely(can_alloc && smp_load_acquire(&next_pool_required))) { + if (unlikely(can_alloc && smp_load_acquire(&new_pool_required))) { /* * Zero out zone modifiers, as we don't have specific zone * requirements. Keep the flags related to allocation in atomic @@ -477,9 +476,9 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, } else if (prealloc) { /* * Stack depot already contains this stack trace, but let's - * keep the preallocated memory for the future. + * keep the preallocated memory for future. */ - depot_keep_next_pool(&prealloc); + depot_keep_new_pool(&prealloc); } =20 raw_spin_unlock_irqrestore(&pool_lock, flags); --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4711C197A0 for ; Mon, 20 Nov 2023 17:49:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234144AbjKTRtl (ORCPT ); Mon, 20 Nov 2023 12:49:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234254AbjKTRtS (ORCPT ); Mon, 20 Nov 2023 12:49:18 -0500 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 291A6D7D for ; Mon, 20 Nov 2023 09:48:37 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502515; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Wo0lOk4QF0V4/CSryrBtBcTGMr2NPIzDQs2c2iiME6Q=; b=mVlXzudgWPREwFPbPjEzWKl0pkuPrGrBfXgV/o3hu2wbrexzrKyl7c+k+ldkpF3cqIoiwI u8DO0T3MhAJP+5xhUN4eko0SgcoGz172qfdNSCMVSIN1yVWwfrjX7hnhKKWOfY2ZNwgi4e RtBwt9lIOYU3HUK95YFtEZQHsBHOLqY= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 10/22] lib/stackdepot: store next pool pointer in new_pool Date: Mon, 20 Nov 2023 18:47:08 +0100 Message-Id: <448bc18296c16bef95cb3167697be6583dcc8ce3.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Instead of using the last pointer in stack_pools for storing the pointer to a new pool (which does not yet store any stack records), use a new new_pool variable. This a purely code readability change: it seems more logical to store the pointer to a pool with a special meaning in a dedicated variable. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- lib/stackdepot.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index a38661beab97..68c1ac9aa916 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -85,6 +85,8 @@ static unsigned int stack_hash_mask; =20 /* Array of memory regions that store stack traces. */ static void *stack_pools[DEPOT_MAX_POOLS]; +/* Newly allocated pool that is not yet added to stack_pools. */ +static void *new_pool; /* Currently used pool in stack_pools. */ static int pool_index; /* Offset to the unused space in the currently used pool. */ @@ -241,7 +243,7 @@ static void depot_keep_new_pool(void **prealloc) * as long as we do not exceed the maximum number of pools. */ if (pool_index + 1 < DEPOT_MAX_POOLS) { - stack_pools[pool_index + 1] =3D *prealloc; + new_pool =3D *prealloc; *prealloc =3D NULL; } =20 @@ -272,6 +274,8 @@ static bool depot_update_pools(size_t required_size, vo= id **prealloc) * stack_depot_fetch(). */ WRITE_ONCE(pool_index, pool_index + 1); + stack_pools[pool_index] =3D new_pool; + new_pool =3D NULL; pool_offset =3D 0; =20 /* --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9ECD8C197A0 for ; Mon, 20 Nov 2023 17:49:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234589AbjKTRto (ORCPT ); Mon, 20 Nov 2023 12:49:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234261AbjKTRtS (ORCPT ); Mon, 20 Nov 2023 12:49:18 -0500 Received: from out-175.mta0.migadu.com (out-175.mta0.migadu.com [91.218.175.175]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DFEE171D for ; Mon, 20 Nov 2023 09:48:37 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502515; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+N1Q7uFgicZ/Pf0RFILDijpppowVMY0ExiNLLtkdgaQ=; b=RxqnWJ/WbNov6GNDVKKl98NdJigJDFyuUx5XrfpgY0Y/FIFkxZ8cb2F/DaXDPkvN4oYnyI w7lMzmrfXQRH2KCXJzK07x0GGzxp0h1cjOV+z4h6XLtv4ZtoYRFtRsvvF70WP3/hsS5GYv gtRARyq+ePtSURhjvSTg/rB+k7qi5sM= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 11/22] lib/stackdepot: store free stack records in a freelist Date: Mon, 20 Nov 2023 18:47:09 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Instead of using the global pool_offset variable to find a free slot when storing a new stack record, mainlain a freelist of free slots within the allocated stack pools. A global next_stack variable is used as the head of the freelist, and the next field in the stack_record struct is reused as freelist link (when the record is not in the freelist, this field is used as a link in the hash table). This is preparatory patch for implementing the eviction of stack records from the stack depot. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- Changes v2->v3: - Add parentheses when referring to function calls in comments. Changes v1->v2: - Fix out-of-bounds when initializing a pool. --- lib/stackdepot.c | 131 +++++++++++++++++++++++++++++------------------ 1 file changed, 82 insertions(+), 49 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 68c1ac9aa916..a5eff165c0d5 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -54,8 +54,8 @@ union handle_parts { }; =20 struct stack_record { - struct stack_record *next; /* Link in the hash table */ - u32 hash; /* Hash in the hash table */ + struct stack_record *next; /* Link in hash table or freelist */ + u32 hash; /* Hash in hash table */ u32 size; /* Number of stored frames */ union handle_parts handle; unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */ @@ -87,10 +87,10 @@ static unsigned int stack_hash_mask; static void *stack_pools[DEPOT_MAX_POOLS]; /* Newly allocated pool that is not yet added to stack_pools. */ static void *new_pool; -/* Currently used pool in stack_pools. */ -static int pool_index; -/* Offset to the unused space in the currently used pool. */ -static size_t pool_offset; +/* Number of pools in stack_pools. */ +static int pools_num; +/* Next stack in the freelist of stack records within stack_pools. */ +static struct stack_record *next_stack; /* Lock that protects the variables above. */ static DEFINE_RAW_SPINLOCK(pool_lock); /* @@ -226,6 +226,42 @@ int stack_depot_init(void) } EXPORT_SYMBOL_GPL(stack_depot_init); =20 +/* Initializes a stack depol pool. */ +static void depot_init_pool(void *pool) +{ + const int records_in_pool =3D DEPOT_POOL_SIZE / DEPOT_STACK_RECORD_SIZE; + int i, offset; + + /* Initialize handles and link stack records to each other. */ + for (i =3D 0, offset =3D 0; + offset <=3D DEPOT_POOL_SIZE - DEPOT_STACK_RECORD_SIZE; + i++, offset +=3D DEPOT_STACK_RECORD_SIZE) { + struct stack_record *stack =3D pool + offset; + + stack->handle.pool_index =3D pools_num; + stack->handle.offset =3D offset >> DEPOT_STACK_ALIGN; + stack->handle.extra =3D 0; + + if (i < records_in_pool - 1) + stack->next =3D (void *)stack + DEPOT_STACK_RECORD_SIZE; + else + stack->next =3D NULL; + } + + /* Link stack records into the freelist. */ + WARN_ON(next_stack); + next_stack =3D pool; + + /* Save reference to the pool to be used by depot_fetch_stack(). */ + stack_pools[pools_num] =3D pool; + + /* + * WRITE_ONCE() pairs with potential concurrent read in + * depot_fetch_stack(). + */ + WRITE_ONCE(pools_num, pools_num + 1); +} + /* Keeps the preallocated memory to be used for a new stack depot pool. */ static void depot_keep_new_pool(void **prealloc) { @@ -242,7 +278,7 @@ static void depot_keep_new_pool(void **prealloc) * Use the preallocated memory for the new pool * as long as we do not exceed the maximum number of pools. */ - if (pool_index + 1 < DEPOT_MAX_POOLS) { + if (pools_num < DEPOT_MAX_POOLS) { new_pool =3D *prealloc; *prealloc =3D NULL; } @@ -258,45 +294,42 @@ static void depot_keep_new_pool(void **prealloc) } =20 /* Updates references to the current and the next stack depot pools. */ -static bool depot_update_pools(size_t required_size, void **prealloc) +static bool depot_update_pools(void **prealloc) { - /* Check if there is not enough space in the current pool. */ - if (unlikely(pool_offset + required_size > DEPOT_POOL_SIZE)) { - /* Bail out if we reached the pool limit. */ - if (unlikely(pool_index + 1 >=3D DEPOT_MAX_POOLS)) { - WARN_ONCE(1, "Stack depot reached limit capacity"); - return false; - } + /* Check if we still have objects in the freelist. */ + if (next_stack) + goto out_keep_prealloc; =20 - /* - * Move on to the new pool. - * WRITE_ONCE() pairs with potential concurrent read in - * stack_depot_fetch(). - */ - WRITE_ONCE(pool_index, pool_index + 1); - stack_pools[pool_index] =3D new_pool; + /* Check if we have a new pool saved and use it. */ + if (new_pool) { + depot_init_pool(new_pool); new_pool =3D NULL; - pool_offset =3D 0; =20 - /* - * If the maximum number of pools is not reached, take note - * that yet another new pool needs to be allocated. - * smp_store_release() pairs with smp_load_acquire() in - * stack_depot_save(). - */ - if (pool_index + 1 < DEPOT_MAX_POOLS) + /* Take note that we might need a new new_pool. */ + if (pools_num < DEPOT_MAX_POOLS) smp_store_release(&new_pool_required, 1); + + /* Try keeping the preallocated memory for new_pool. */ + goto out_keep_prealloc; + } + + /* Bail out if we reached the pool limit. */ + if (unlikely(pools_num >=3D DEPOT_MAX_POOLS)) { + WARN_ONCE(1, "Stack depot reached limit capacity"); + return false; } =20 - /* Check if the current pool is not yet allocated. */ - if (*prealloc && stack_pools[pool_index] =3D=3D NULL) { - /* Use the preallocated memory for the current pool. */ - stack_pools[pool_index] =3D *prealloc; + /* Check if we have preallocated memory and use it. */ + if (*prealloc) { + depot_init_pool(*prealloc); *prealloc =3D NULL; return true; } =20 - /* Otherwise, try using the preallocated memory for a new pool. */ + return false; + +out_keep_prealloc: + /* Keep the preallocated memory for a new pool if required. */ if (*prealloc) depot_keep_new_pool(prealloc); return true; @@ -307,35 +340,35 @@ static struct stack_record * depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **preal= loc) { struct stack_record *stack; - size_t required_size =3D DEPOT_STACK_RECORD_SIZE; =20 /* Update current and new pools if required and possible. */ - if (!depot_update_pools(required_size, prealloc)) + if (!depot_update_pools(prealloc)) return NULL; =20 - /* Check if we have a pool to save the stack trace. */ - if (stack_pools[pool_index] =3D=3D NULL) + /* Check if we have a stack record to save the stack trace. */ + stack =3D next_stack; + if (!stack) return NULL; =20 + /* Advance the freelist. */ + next_stack =3D stack->next; + /* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */ if (size > CONFIG_STACKDEPOT_MAX_FRAMES) size =3D CONFIG_STACKDEPOT_MAX_FRAMES; =20 /* Save the stack trace. */ - stack =3D stack_pools[pool_index] + pool_offset; + stack->next =3D NULL; stack->hash =3D hash; stack->size =3D size; - stack->handle.pool_index =3D pool_index; - stack->handle.offset =3D pool_offset >> DEPOT_STACK_ALIGN; - stack->handle.extra =3D 0; + /* stack->handle is already filled in by depot_init_pool(). */ memcpy(stack->entries, entries, flex_array_size(stack, entries, size)); - pool_offset +=3D required_size; =20 /* * Let KMSAN know the stored stack record is initialized. This shall * prevent false positive reports if instrumented code accesses it. */ - kmsan_unpoison_memory(stack, required_size); + kmsan_unpoison_memory(stack, DEPOT_STACK_RECORD_SIZE); =20 return stack; } @@ -345,16 +378,16 @@ static struct stack_record *depot_fetch_stack(depot_s= tack_handle_t handle) union handle_parts parts =3D { .handle =3D handle }; /* * READ_ONCE() pairs with potential concurrent write in - * depot_update_pools(). + * depot_init_pool(). */ - int pool_index_cached =3D READ_ONCE(pool_index); + int pools_num_cached =3D READ_ONCE(pools_num); void *pool; size_t offset =3D parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack; =20 - if (parts.pool_index > pool_index_cached) { + if (parts.pool_index > pools_num_cached) { WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", - parts.pool_index, pool_index_cached, handle); + parts.pool_index, pools_num_cached, handle); return NULL; } =20 --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40DFBC197A0 for ; Mon, 20 Nov 2023 17:50:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234570AbjKTRuJ (ORCPT ); Mon, 20 Nov 2023 12:50:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234592AbjKTRts (ORCPT ); Mon, 20 Nov 2023 12:49:48 -0500 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69A7210D4 for ; Mon, 20 Nov 2023 09:49:39 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502577; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K4xViYAWVaV6VQ5HtL4BYhsbr4MB9DPwoOHOaowHM8k=; b=IaUsjEmoPRLDB8+q+N1/FFx4BQ3dNpy2/8UK1Gk7f8jxcPQzpMGtk0vCNWAd3ep43VVaLY YSfB7RGeC4krK+GbjgpVSoqyBiDp1Yja1RT2FgG6vH1HpRdUzo+USs4eje1zfRoqc8P41c 5glC0pVcsGIq8X4efr6ATYrkrC3nrgc= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 12/22] lib/stackdepot: use read/write lock Date: Mon, 20 Nov 2023 18:47:10 +0100 Message-Id: <9f81ffcc4bb422ebb6326a65a770bf1918634cbb.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Currently, stack depot uses the following locking scheme: 1. Lock-free accesses when looking up a stack record, which allows to have multiple users to look up records in parallel; 2. Spinlock for protecting the stack depot pools and the hash table when adding a new record. For implementing the eviction of stack traces from stack depot, the lock-free approach is not going to work anymore, as we will need to be able to also remove records from the hash table. Convert the spinlock into a read/write lock, and drop the atomic accesses, as they are no longer required. Looking up stack traces is now protected by the read lock and adding new records - by the write lock. One of the following patches will add a new function for evicting stack records, which will be protected by the write lock as well. With this change, multiple users can still look up records in parallel. This is preparatory patch for implementing the eviction of stack records from the stack depot. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov Reviewed-by: Oscar Salvador --- Changed v2->v3: - Use lockdep_assert_held_read annotation in depot_fetch_stack. Changes v1->v2: - Add lockdep_assert annotations. --- lib/stackdepot.c | 87 +++++++++++++++++++++++++----------------------- 1 file changed, 46 insertions(+), 41 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index a5eff165c0d5..8378b32b5310 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -91,15 +92,15 @@ static void *new_pool; static int pools_num; /* Next stack in the freelist of stack records within stack_pools. */ static struct stack_record *next_stack; -/* Lock that protects the variables above. */ -static DEFINE_RAW_SPINLOCK(pool_lock); /* * Stack depot tries to keep an extra pool allocated even before it runs o= ut * of space in the currently used pool. This flag marks whether this extra= pool * needs to be allocated. It has the value 0 when either an extra pool is = not * yet allocated or if the limit on the number of pools is reached. */ -static int new_pool_required =3D 1; +static bool new_pool_required =3D true; +/* Lock that protects the variables above. */ +static DEFINE_RWLOCK(pool_rwlock); =20 static int __init disable_stack_depot(char *str) { @@ -232,6 +233,8 @@ static void depot_init_pool(void *pool) const int records_in_pool =3D DEPOT_POOL_SIZE / DEPOT_STACK_RECORD_SIZE; int i, offset; =20 + lockdep_assert_held_write(&pool_rwlock); + /* Initialize handles and link stack records to each other. */ for (i =3D 0, offset =3D 0; offset <=3D DEPOT_POOL_SIZE - DEPOT_STACK_RECORD_SIZE; @@ -254,22 +257,17 @@ static void depot_init_pool(void *pool) =20 /* Save reference to the pool to be used by depot_fetch_stack(). */ stack_pools[pools_num] =3D pool; - - /* - * WRITE_ONCE() pairs with potential concurrent read in - * depot_fetch_stack(). - */ - WRITE_ONCE(pools_num, pools_num + 1); + pools_num++; } =20 /* Keeps the preallocated memory to be used for a new stack depot pool. */ static void depot_keep_new_pool(void **prealloc) { + lockdep_assert_held_write(&pool_rwlock); + /* * If a new pool is already saved or the maximum number of * pools is reached, do not use the preallocated memory. - * Access new_pool_required non-atomically, as there are no concurrent - * write accesses to this variable. */ if (!new_pool_required) return; @@ -287,15 +285,15 @@ static void depot_keep_new_pool(void **prealloc) * At this point, either a new pool is kept or the maximum * number of pools is reached. In either case, take note that * keeping another pool is not required. - * smp_store_release() pairs with smp_load_acquire() in - * stack_depot_save(). */ - smp_store_release(&new_pool_required, 0); + new_pool_required =3D false; } =20 /* Updates references to the current and the next stack depot pools. */ static bool depot_update_pools(void **prealloc) { + lockdep_assert_held_write(&pool_rwlock); + /* Check if we still have objects in the freelist. */ if (next_stack) goto out_keep_prealloc; @@ -307,7 +305,7 @@ static bool depot_update_pools(void **prealloc) =20 /* Take note that we might need a new new_pool. */ if (pools_num < DEPOT_MAX_POOLS) - smp_store_release(&new_pool_required, 1); + new_pool_required =3D true; =20 /* Try keeping the preallocated memory for new_pool. */ goto out_keep_prealloc; @@ -341,6 +339,8 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) { struct stack_record *stack; =20 + lockdep_assert_held_write(&pool_rwlock); + /* Update current and new pools if required and possible. */ if (!depot_update_pools(prealloc)) return NULL; @@ -376,18 +376,15 @@ depot_alloc_stack(unsigned long *entries, int size, u= 32 hash, void **prealloc) static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle) { union handle_parts parts =3D { .handle =3D handle }; - /* - * READ_ONCE() pairs with potential concurrent write in - * depot_init_pool(). - */ - int pools_num_cached =3D READ_ONCE(pools_num); void *pool; size_t offset =3D parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack; =20 - if (parts.pool_index > pools_num_cached) { + lockdep_assert_held_read(&pool_rwlock); + + if (parts.pool_index > pools_num) { WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", - parts.pool_index, pools_num_cached, handle); + parts.pool_index, pools_num, handle); return NULL; } =20 @@ -429,6 +426,8 @@ static inline struct stack_record *find_stack(struct st= ack_record *bucket, { struct stack_record *found; =20 + lockdep_assert_held(&pool_rwlock); + for (found =3D bucket; found; found =3D found->next) { if (found->hash =3D=3D hash && found->size =3D=3D size && @@ -446,6 +445,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, depot_stack_handle_t handle =3D 0; struct page *page =3D NULL; void *prealloc =3D NULL; + bool need_alloc =3D false; unsigned long flags; u32 hash; =20 @@ -465,22 +465,26 @@ depot_stack_handle_t __stack_depot_save(unsigned long= *entries, hash =3D hash_stack(entries, nr_entries); bucket =3D &stack_table[hash & stack_hash_mask]; =20 - /* - * Fast path: look the stack trace up without locking. - * smp_load_acquire() pairs with smp_store_release() to |bucket| below. - */ - found =3D find_stack(smp_load_acquire(bucket), entries, nr_entries, hash); - if (found) + read_lock_irqsave(&pool_rwlock, flags); + + /* Fast path: look the stack trace up without full locking. */ + found =3D find_stack(*bucket, entries, nr_entries, hash); + if (found) { + read_unlock_irqrestore(&pool_rwlock, flags); goto exit; + } + + /* Take note if another stack pool needs to be allocated. */ + if (new_pool_required) + need_alloc =3D true; + + read_unlock_irqrestore(&pool_rwlock, flags); =20 /* - * Check if another stack pool needs to be allocated. If so, allocate - * the memory now: we won't be able to do that under the lock. - * - * smp_load_acquire() pairs with smp_store_release() in - * depot_update_pools() and depot_keep_new_pool(). + * Allocate memory for a new pool if required now: + * we won't be able to do that under the lock. */ - if (unlikely(can_alloc && smp_load_acquire(&new_pool_required))) { + if (unlikely(can_alloc && need_alloc)) { /* * Zero out zone modifiers, as we don't have specific zone * requirements. Keep the flags related to allocation in atomic @@ -494,7 +498,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, prealloc =3D page_address(page); } =20 - raw_spin_lock_irqsave(&pool_lock, flags); + write_lock_irqsave(&pool_rwlock, flags); =20 found =3D find_stack(*bucket, entries, nr_entries, hash); if (!found) { @@ -503,11 +507,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long = *entries, =20 if (new) { new->next =3D *bucket; - /* - * smp_store_release() pairs with smp_load_acquire() - * from |bucket| above. - */ - smp_store_release(bucket, new); + *bucket =3D new; found =3D new; } } else if (prealloc) { @@ -518,7 +518,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, depot_keep_new_pool(&prealloc); } =20 - raw_spin_unlock_irqrestore(&pool_lock, flags); + write_unlock_irqrestore(&pool_rwlock, flags); exit: if (prealloc) { /* Stack depot didn't use this memory, free it. */ @@ -542,6 +542,7 @@ unsigned int stack_depot_fetch(depot_stack_handle_t han= dle, unsigned long **entries) { struct stack_record *stack; + unsigned long flags; =20 *entries =3D NULL; /* @@ -553,8 +554,12 @@ unsigned int stack_depot_fetch(depot_stack_handle_t ha= ndle, if (!handle || stack_depot_disabled) return 0; =20 + read_lock_irqsave(&pool_rwlock, flags); + stack =3D depot_fetch_stack(handle); =20 + read_unlock_irqrestore(&pool_rwlock, flags); + *entries =3D stack->entries; return stack->size; } --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 050C7C5AD4C for ; Mon, 20 Nov 2023 17:50:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234624AbjKTRuO (ORCPT ); Mon, 20 Nov 2023 12:50:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49320 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234599AbjKTRtt (ORCPT ); Mon, 20 Nov 2023 12:49:49 -0500 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [IPv6:2001:41d0:1004:224b::bd]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E2E610D5 for ; Mon, 20 Nov 2023 09:49:39 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502578; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JJPmOktxCpdhFxDsq8sCddRT3Qn7jxR2DhkERqO3NMk=; b=Ru67pJEW7nzqb9rpO9yuZYxURTiycM1daQ55M4avqe1G86/dIuZUOw3dlKb408oXGg6x5O JLJSygolUyzo1EhZYq8z5/W03AxWgm/1aMH2K0UPV7/E3PTSKcGiP2gUzwgoDhjawwRIqO osUPMvkhvTwmI4K9sg+oiHZAmIKPW1E= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 13/22] lib/stackdepot: use list_head for stack record links Date: Mon, 20 Nov 2023 18:47:11 +0100 Message-Id: <4787d9a584cd33433d9ee1846b17fa3d3e1987ad.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Switch stack_record to use list_head for links in the hash table and in the freelist. This will allow removing entries from the hash table buckets. This is preparatory patch for implementing the eviction of stack records from the stack depot. Signed-off-by: Andrey Konovalov --- Changes v2->v3: - Use the proper number of entries for initializing the stack table when alloc_large_system_hash() auto-calculates the number. Changes v1->v2: - Use list_head instead of open-coding backward links. --- lib/stackdepot.c | 87 ++++++++++++++++++++++++++++-------------------- 1 file changed, 50 insertions(+), 37 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 8378b32b5310..4bb0af423f82 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -55,7 +56,7 @@ union handle_parts { }; =20 struct stack_record { - struct stack_record *next; /* Link in hash table or freelist */ + struct list_head list; /* Links in hash table or freelist */ u32 hash; /* Hash in hash table */ u32 size; /* Number of stored frames */ union handle_parts handle; @@ -77,21 +78,21 @@ static bool __stack_depot_early_init_passed __initdata; /* Initial seed for jhash2. */ #define STACK_HASH_SEED 0x9747b28c =20 -/* Hash table of pointers to stored stack traces. */ -static struct stack_record **stack_table; +/* Hash table of stored stack records. */ +static struct list_head *stack_table; /* Fixed order of the number of table buckets. Used when KASAN is enabled.= */ static unsigned int stack_bucket_number_order; /* Hash mask for indexing the table. */ static unsigned int stack_hash_mask; =20 -/* Array of memory regions that store stack traces. */ +/* Array of memory regions that store stack records. */ static void *stack_pools[DEPOT_MAX_POOLS]; /* Newly allocated pool that is not yet added to stack_pools. */ static void *new_pool; /* Number of pools in stack_pools. */ static int pools_num; -/* Next stack in the freelist of stack records within stack_pools. */ -static struct stack_record *next_stack; +/* Freelist of stack records within stack_pools. */ +static LIST_HEAD(free_stacks); /* * Stack depot tries to keep an extra pool allocated even before it runs o= ut * of space in the currently used pool. This flag marks whether this extra= pool @@ -116,6 +117,15 @@ void __init stack_depot_request_early_init(void) __stack_depot_early_init_requested =3D true; } =20 +/* Initialize list_head's within the hash table. */ +static void init_stack_table(unsigned long entries) +{ + unsigned long i; + + for (i =3D 0; i < entries; i++) + INIT_LIST_HEAD(&stack_table[i]); +} + /* Allocates a hash table via memblock. Can only be used during early boot= . */ int __init stack_depot_early_init(void) { @@ -152,16 +162,16 @@ int __init stack_depot_early_init(void) =20 /* * If stack_bucket_number_order is not set, leave entries as 0 to rely - * on the automatic calculations performed by alloc_large_system_hash. + * on the automatic calculations performed by alloc_large_system_hash(). */ if (stack_bucket_number_order) entries =3D 1UL << stack_bucket_number_order; pr_info("allocating hash table via alloc_large_system_hash\n"); stack_table =3D alloc_large_system_hash("stackdepot", - sizeof(struct stack_record *), + sizeof(struct list_head), entries, STACK_HASH_TABLE_SCALE, - HASH_EARLY | HASH_ZERO, + HASH_EARLY, NULL, &stack_hash_mask, 1UL << STACK_BUCKET_NUMBER_ORDER_MIN, @@ -171,6 +181,14 @@ int __init stack_depot_early_init(void) stack_depot_disabled =3D true; return -ENOMEM; } + if (!entries) { + /* + * Obtain the number of entries that was calculated by + * alloc_large_system_hash(). + */ + entries =3D stack_hash_mask + 1; + } + init_stack_table(entries); =20 return 0; } @@ -211,7 +229,7 @@ int stack_depot_init(void) entries =3D 1UL << STACK_BUCKET_NUMBER_ORDER_MAX; =20 pr_info("allocating hash table of %lu entries via kvcalloc\n", entries); - stack_table =3D kvcalloc(entries, sizeof(struct stack_record *), GFP_KERN= EL); + stack_table =3D kvcalloc(entries, sizeof(struct list_head), GFP_KERNEL); if (!stack_table) { pr_err("hash table allocation failed, disabling\n"); stack_depot_disabled =3D true; @@ -219,6 +237,7 @@ int stack_depot_init(void) goto out_unlock; } stack_hash_mask =3D entries - 1; + init_stack_table(entries); =20 out_unlock: mutex_unlock(&stack_depot_init_mutex); @@ -230,31 +249,24 @@ EXPORT_SYMBOL_GPL(stack_depot_init); /* Initializes a stack depol pool. */ static void depot_init_pool(void *pool) { - const int records_in_pool =3D DEPOT_POOL_SIZE / DEPOT_STACK_RECORD_SIZE; - int i, offset; + int offset; =20 lockdep_assert_held_write(&pool_rwlock); =20 - /* Initialize handles and link stack records to each other. */ - for (i =3D 0, offset =3D 0; - offset <=3D DEPOT_POOL_SIZE - DEPOT_STACK_RECORD_SIZE; - i++, offset +=3D DEPOT_STACK_RECORD_SIZE) { + WARN_ON(!list_empty(&free_stacks)); + + /* Initialize handles and link stack records into the freelist. */ + for (offset =3D 0; offset <=3D DEPOT_POOL_SIZE - DEPOT_STACK_RECORD_SIZE; + offset +=3D DEPOT_STACK_RECORD_SIZE) { struct stack_record *stack =3D pool + offset; =20 stack->handle.pool_index =3D pools_num; stack->handle.offset =3D offset >> DEPOT_STACK_ALIGN; stack->handle.extra =3D 0; =20 - if (i < records_in_pool - 1) - stack->next =3D (void *)stack + DEPOT_STACK_RECORD_SIZE; - else - stack->next =3D NULL; + list_add(&stack->list, &free_stacks); } =20 - /* Link stack records into the freelist. */ - WARN_ON(next_stack); - next_stack =3D pool; - /* Save reference to the pool to be used by depot_fetch_stack(). */ stack_pools[pools_num] =3D pool; pools_num++; @@ -295,7 +307,7 @@ static bool depot_update_pools(void **prealloc) lockdep_assert_held_write(&pool_rwlock); =20 /* Check if we still have objects in the freelist. */ - if (next_stack) + if (!list_empty(&free_stacks)) goto out_keep_prealloc; =20 /* Check if we have a new pool saved and use it. */ @@ -346,19 +358,18 @@ depot_alloc_stack(unsigned long *entries, int size, u= 32 hash, void **prealloc) return NULL; =20 /* Check if we have a stack record to save the stack trace. */ - stack =3D next_stack; - if (!stack) + if (list_empty(&free_stacks)) return NULL; =20 - /* Advance the freelist. */ - next_stack =3D stack->next; + /* Get and unlink the first entry from the freelist. */ + stack =3D list_first_entry(&free_stacks, struct stack_record, list); + list_del(&stack->list); =20 /* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */ if (size > CONFIG_STACKDEPOT_MAX_FRAMES) size =3D CONFIG_STACKDEPOT_MAX_FRAMES; =20 /* Save the stack trace. */ - stack->next =3D NULL; stack->hash =3D hash; stack->size =3D size; /* stack->handle is already filled in by depot_init_pool(). */ @@ -420,15 +431,17 @@ int stackdepot_memcmp(const unsigned long *u1, const = unsigned long *u2, } =20 /* Finds a stack in a bucket of the hash table. */ -static inline struct stack_record *find_stack(struct stack_record *bucket, +static inline struct stack_record *find_stack(struct list_head *bucket, unsigned long *entries, int size, u32 hash) { + struct list_head *pos; struct stack_record *found; =20 lockdep_assert_held(&pool_rwlock); =20 - for (found =3D bucket; found; found =3D found->next) { + list_for_each(pos, bucket) { + found =3D list_entry(pos, struct stack_record, list); if (found->hash =3D=3D hash && found->size =3D=3D size && !stackdepot_memcmp(entries, found->entries, size)) @@ -441,7 +454,8 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, unsigned int nr_entries, gfp_t alloc_flags, bool can_alloc) { - struct stack_record *found =3D NULL, **bucket; + struct list_head *bucket; + struct stack_record *found =3D NULL; depot_stack_handle_t handle =3D 0; struct page *page =3D NULL; void *prealloc =3D NULL; @@ -468,7 +482,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, read_lock_irqsave(&pool_rwlock, flags); =20 /* Fast path: look the stack trace up without full locking. */ - found =3D find_stack(*bucket, entries, nr_entries, hash); + found =3D find_stack(bucket, entries, nr_entries, hash); if (found) { read_unlock_irqrestore(&pool_rwlock, flags); goto exit; @@ -500,14 +514,13 @@ depot_stack_handle_t __stack_depot_save(unsigned long= *entries, =20 write_lock_irqsave(&pool_rwlock, flags); =20 - found =3D find_stack(*bucket, entries, nr_entries, hash); + found =3D find_stack(bucket, entries, nr_entries, hash); if (!found) { struct stack_record *new =3D depot_alloc_stack(entries, nr_entries, hash, &prealloc); =20 if (new) { - new->next =3D *bucket; - *bucket =3D new; + list_add(&new->list, bucket); found =3D new; } } else if (prealloc) { --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E82D8C197A0 for ; Mon, 20 Nov 2023 17:50:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234078AbjKTRuL (ORCPT ); Mon, 20 Nov 2023 12:50:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233605AbjKTRts (ORCPT ); Mon, 20 Nov 2023 12:49:48 -0500 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [IPv6:2001:41d0:1004:224b::b8]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9CEE10DD for ; Mon, 20 Nov 2023 09:49:40 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502578; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AmubiAZbFJ0d/i3HqBc+VhVD2T8fru9oX5DWKdU3rlA=; b=b2OIEP3BJYVimjqmep3gX4pnHU69uhP3rz4BbIU0wDtcOHhahRQdj/mDShPRiA2HDFVZhX ObfN7eBTcN91SgmffyLxHsXabiv3RbporAg2HdC9O1DTTM3xtlUsATOXQ2XYASwgncbBwR 7K4umBHx7gSfcQI4eOh8RKYS2iCumFg= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 14/22] kmsan: use stack_depot_save instead of __stack_depot_save Date: Mon, 20 Nov 2023 18:47:12 +0100 Message-Id: <18092240699efdc6acd78b51e41ea782953e6c8d.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Make KMSAN use stack_depot_save instead of __stack_depot_save, as it always passes true to __stack_depot_save as the last argument. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- Changes v1->v2: - This is a new patch. --- mm/kmsan/core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/kmsan/core.c b/mm/kmsan/core.c index c19f47af0424..cf2d70e9c9a5 100644 --- a/mm/kmsan/core.c +++ b/mm/kmsan/core.c @@ -76,7 +76,7 @@ depot_stack_handle_t kmsan_save_stack_with_flags(gfp_t fl= ags, /* Don't sleep. */ flags &=3D ~(__GFP_DIRECT_RECLAIM | __GFP_KSWAPD_RECLAIM); =20 - handle =3D __stack_depot_save(entries, nr_entries, flags, true); + handle =3D stack_depot_save(entries, nr_entries, flags); return stack_depot_set_extra_bits(handle, extra); } =20 @@ -185,11 +185,10 @@ depot_stack_handle_t kmsan_internal_chain_origin(depo= t_stack_handle_t id) /* * @entries is a local var in non-instrumented code, so KMSAN does not * know it is initialized. Explicitly unpoison it to avoid false - * positives when __stack_depot_save() passes it to instrumented code. + * positives when stack_depot_save() passes it to instrumented code. */ kmsan_internal_unpoison_memory(entries, sizeof(entries), false); - handle =3D __stack_depot_save(entries, ARRAY_SIZE(entries), __GFP_HIGH, - true); + handle =3D stack_depot_save(entries, ARRAY_SIZE(entries), __GFP_HIGH); return stack_depot_set_extra_bits(handle, extra_bits); } =20 --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E150C2BB3F for ; Mon, 20 Nov 2023 17:50:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234664AbjKTRuQ (ORCPT ); Mon, 20 Nov 2023 12:50:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234309AbjKTRtu (ORCPT ); Mon, 20 Nov 2023 12:49:50 -0500 Received: from out-176.mta0.migadu.com (out-176.mta0.migadu.com [91.218.175.176]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B36A10E6 for ; Mon, 20 Nov 2023 09:49:41 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502579; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aXTF/ovgO7tSDGaC/rtVyVWMqky+xGAg2LPsWIiIw38=; b=HqbyNSHD4r9vYA816UIOJaXgIqcjElz6erC2e41iS8jUsO6pNaIMU40yawD+G8CERk8/mB qdv7+Ypo8jZ0ZcLL7hUCGbmu0MDX0b6jRsskfd3hDjPvU8Dgx5Nmli1NgQFC70MO8T/FHR /N3gcwtihjoZvi89Omg8LoW5wxj9aNk= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 15/22] lib/stackdepot, kasan: add flags to __stack_depot_save and rename Date: Mon, 20 Nov 2023 18:47:13 +0100 Message-Id: <645fa15239621eebbd3a10331e5864b718839512.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Change the bool can_alloc argument of __stack_depot_save to a u32 argument that accepts a set of flags. The following patch will add another flag to stack_depot_save_flags besides the existing STACK_DEPOT_FLAG_CAN_ALLOC. Also rename the function to stack_depot_save_flags, as __stack_depot_save is a cryptic name, Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- Changes v2->v3: - WARN_ON invalid flags in stack_depot_save_flags. Changes v1->v2: - This is a new patch. --- include/linux/stackdepot.h | 36 +++++++++++++++++++++++++----------- lib/stackdepot.c | 16 +++++++++++----- mm/kasan/common.c | 7 ++++--- mm/kasan/generic.c | 9 +++++---- mm/kasan/kasan.h | 2 +- mm/kasan/tags.c | 3 ++- 6 files changed, 48 insertions(+), 25 deletions(-) diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index e58306783d8e..0b262e14144e 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -32,6 +32,17 @@ typedef u32 depot_stack_handle_t; */ #define STACK_DEPOT_EXTRA_BITS 5 =20 +typedef u32 depot_flags_t; + +/* + * Flags that can be passed to stack_depot_save_flags(); see the comment n= ext + * to its declaration for more details. + */ +#define STACK_DEPOT_FLAG_CAN_ALLOC ((depot_flags_t)0x0001) + +#define STACK_DEPOT_FLAGS_NUM 1 +#define STACK_DEPOT_FLAGS_MASK ((depot_flags_t)((1 << STACK_DEPOT_FLAGS_NU= M) - 1)) + /* * Using stack depot requires its initialization, which can be done in 3 w= ays: * @@ -69,31 +80,34 @@ static inline int stack_depot_early_init(void) { return= 0; } #endif =20 /** - * __stack_depot_save - Save a stack trace to stack depot + * stack_depot_save_flags - Save a stack trace to stack depot * * @entries: Pointer to the stack trace * @nr_entries: Number of frames in the stack * @alloc_flags: Allocation GFP flags - * @can_alloc: Allocate stack pools (increased chance of failure if false) + * @depot_flags: Stack depot flags + * + * Saves a stack trace from @entries array of size @nr_entries. * - * Saves a stack trace from @entries array of size @nr_entries. If @can_al= loc is - * %true, stack depot can replenish the stack pools in case no space is le= ft - * (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, a= voids - * any allocations and fails if no space is left to store the stack trace. + * If STACK_DEPOT_FLAG_CAN_ALLOC is set in @depot_flags, stack depot can + * replenish the stack pools in case no space is left (allocates using GFP + * flags of @alloc_flags). Otherwise, stack depot avoids any allocations a= nd + * fails if no space is left to store the stack trace. * * If the provided stack trace comes from the interrupt context, only the = part * up to the interrupt entry is saved. * - * Context: Any context, but setting @can_alloc to %false is required if + * Context: Any context, but setting STACK_DEPOT_FLAG_CAN_ALLOC is require= d if * alloc_pages() cannot be used from the current context. Current= ly * this is the case for contexts where neither %GFP_ATOMIC nor * %GFP_NOWAIT can be used (NMI, raw_spin_lock). * * Return: Handle of the stack struct stored in depot, 0 on failure */ -depot_stack_handle_t __stack_depot_save(unsigned long *entries, - unsigned int nr_entries, - gfp_t gfp_flags, bool can_alloc); +depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, + unsigned int nr_entries, + gfp_t gfp_flags, + depot_flags_t depot_flags); =20 /** * stack_depot_save - Save a stack trace to stack depot @@ -103,7 +117,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *= entries, * @alloc_flags: Allocation GFP flags * * Context: Contexts where allocations via alloc_pages() are allowed. - * See __stack_depot_save() for more details. + * See stack_depot_save_flags() for more details. * * Return: Handle of the stack trace stored in depot, 0 on failure */ diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 4bb0af423f82..59d61d5c09a7 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -450,19 +450,24 @@ static inline struct stack_record *find_stack(struct = list_head *bucket, return NULL; } =20 -depot_stack_handle_t __stack_depot_save(unsigned long *entries, - unsigned int nr_entries, - gfp_t alloc_flags, bool can_alloc) +depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, + unsigned int nr_entries, + gfp_t alloc_flags, + depot_flags_t depot_flags) { struct list_head *bucket; struct stack_record *found =3D NULL; depot_stack_handle_t handle =3D 0; struct page *page =3D NULL; void *prealloc =3D NULL; + bool can_alloc =3D depot_flags & STACK_DEPOT_FLAG_CAN_ALLOC; bool need_alloc =3D false; unsigned long flags; u32 hash; =20 + if (WARN_ON(depot_flags & ~STACK_DEPOT_FLAGS_MASK)) + return 0; + /* * If this stack trace is from an interrupt, including anything before * interrupt entry usually leads to unbounded stack depot growth. @@ -541,13 +546,14 @@ depot_stack_handle_t __stack_depot_save(unsigned long= *entries, handle =3D found->handle.handle; return handle; } -EXPORT_SYMBOL_GPL(__stack_depot_save); +EXPORT_SYMBOL_GPL(stack_depot_save_flags); =20 depot_stack_handle_t stack_depot_save(unsigned long *entries, unsigned int nr_entries, gfp_t alloc_flags) { - return __stack_depot_save(entries, nr_entries, alloc_flags, true); + return stack_depot_save_flags(entries, nr_entries, alloc_flags, + STACK_DEPOT_FLAG_CAN_ALLOC); } EXPORT_SYMBOL_GPL(stack_depot_save); =20 diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 256930da578a..825a0240ec02 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -37,19 +38,19 @@ struct slab *kasan_addr_to_slab(const void *addr) return NULL; } =20 -depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc) +depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_flags_t depot_fla= gs) { unsigned long entries[KASAN_STACK_DEPTH]; unsigned int nr_entries; =20 nr_entries =3D stack_trace_save(entries, ARRAY_SIZE(entries), 0); - return __stack_depot_save(entries, nr_entries, flags, can_alloc); + return stack_depot_save_flags(entries, nr_entries, flags, depot_flags); } =20 void kasan_set_track(struct kasan_track *track, gfp_t flags) { track->pid =3D current->pid; - track->stack =3D kasan_save_stack(flags, true); + track->stack =3D kasan_save_stack(flags, STACK_DEPOT_FLAG_CAN_ALLOC); } =20 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 4d837ab83f08..5d168c9afb32 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -472,7 +473,7 @@ size_t kasan_metadata_size(struct kmem_cache *cache, bo= ol in_object) sizeof(struct kasan_free_meta) : 0); } =20 -static void __kasan_record_aux_stack(void *addr, bool can_alloc) +static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags) { struct slab *slab =3D kasan_addr_to_slab(addr); struct kmem_cache *cache; @@ -489,17 +490,17 @@ static void __kasan_record_aux_stack(void *addr, bool= can_alloc) return; =20 alloc_meta->aux_stack[1] =3D alloc_meta->aux_stack[0]; - alloc_meta->aux_stack[0] =3D kasan_save_stack(0, can_alloc); + alloc_meta->aux_stack[0] =3D kasan_save_stack(0, depot_flags); } =20 void kasan_record_aux_stack(void *addr) { - return __kasan_record_aux_stack(addr, true); + return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_CAN_ALLOC); } =20 void kasan_record_aux_stack_noalloc(void *addr) { - return __kasan_record_aux_stack(addr, false); + return __kasan_record_aux_stack(addr, 0); } =20 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t f= lags) diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 8b06bab5c406..b29d46b83d1f 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -368,7 +368,7 @@ static inline void kasan_init_cache_meta(struct kmem_ca= che *cache, unsigned int static inline void kasan_init_object_meta(struct kmem_cache *cache, const = void *object) { } #endif =20 -depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc); +depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_flags_t depot_fla= gs); void kasan_set_track(struct kasan_track *track, gfp_t flags); void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t f= lags); void kasan_save_free_info(struct kmem_cache *cache, void *object); diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c index 7dcfe341d48e..4fd32121b0fd 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -101,7 +102,7 @@ static void save_stack_info(struct kmem_cache *cache, v= oid *object, struct kasan_stack_ring_entry *entry; void *old_ptr; =20 - stack =3D kasan_save_stack(gfp_flags, true); + stack =3D kasan_save_stack(gfp_flags, STACK_DEPOT_FLAG_CAN_ALLOC); =20 /* * Prevent save_stack_info() from modifying stack ring --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B3B5C5AD4C for ; Mon, 20 Nov 2023 17:50:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234158AbjKTRuT (ORCPT ); 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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502580; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=91QxaYvk4RHHEJwI4Sc7Oo7z2rlFVPgOoXOer3eAY+g=; b=rZ/C2HcsNzvMwpX5O9VOx1lNSC2GHR0kSTsgEzMvFKq6y+hKBKp3/9Ua+zCoBCJmYeieov wMbZyfFLCbQY6lOshDlPQuKUW5//srMlo9hBj2CFZiAjPs39TBjkS5qlASK6p+8fCOmgfm q8MQh7TtmnvvOGnA2P/0s6mRGFe8vjU= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 16/22] lib/stackdepot: add refcount for records Date: Mon, 20 Nov 2023 18:47:14 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Add a reference counter for how many times a stack records has been added to stack depot. Add a new STACK_DEPOT_FLAG_GET flag to stack_depot_save_flags that instructs the stack depot to increment the refcount. Do not yet decrement the refcount; this is implemented in one of the following patches. Do not yet enable any users to use the flag to avoid overflowing the refcount. This is preparatory patch for implementing the eviction of stack records from the stack depot. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- Changes v1->v2: - Add forgotten refcount_inc() under write lock. - Add STACK_DEPOT_FLAG_GET flag for stack_depot_save_flags. --- include/linux/stackdepot.h | 13 ++++++++++--- lib/stackdepot.c | 12 ++++++++++-- 2 files changed, 20 insertions(+), 5 deletions(-) diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index 0b262e14144e..611716702d73 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -39,8 +39,9 @@ typedef u32 depot_flags_t; * to its declaration for more details. */ #define STACK_DEPOT_FLAG_CAN_ALLOC ((depot_flags_t)0x0001) +#define STACK_DEPOT_FLAG_GET ((depot_flags_t)0x0002) =20 -#define STACK_DEPOT_FLAGS_NUM 1 +#define STACK_DEPOT_FLAGS_NUM 2 #define STACK_DEPOT_FLAGS_MASK ((depot_flags_t)((1 << STACK_DEPOT_FLAGS_NU= M) - 1)) =20 /* @@ -94,6 +95,9 @@ static inline int stack_depot_early_init(void) { return 0= ; } * flags of @alloc_flags). Otherwise, stack depot avoids any allocations a= nd * fails if no space is left to store the stack trace. * + * If STACK_DEPOT_FLAG_GET is set in @depot_flags, stack depot will increm= ent + * the refcount on the saved stack trace if it already exists in stack dep= ot. + * * If the provided stack trace comes from the interrupt context, only the = part * up to the interrupt entry is saved. * @@ -116,8 +120,11 @@ depot_stack_handle_t stack_depot_save_flags(unsigned l= ong *entries, * @nr_entries: Number of frames in the stack * @alloc_flags: Allocation GFP flags * - * Context: Contexts where allocations via alloc_pages() are allowed. - * See stack_depot_save_flags() for more details. + * Does not increment the refcount on the saved stack trace; see + * stack_depot_save_flags() for more details. + * + * Context: Contexts where allocations via alloc_pages() are allowed; + * see stack_depot_save_flags() for more details. * * Return: Handle of the stack trace stored in depot, 0 on failure */ diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 59d61d5c09a7..911dee11bf39 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -60,6 +61,7 @@ struct stack_record { u32 hash; /* Hash in hash table */ u32 size; /* Number of stored frames */ union handle_parts handle; + refcount_t count; unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */ }; =20 @@ -373,6 +375,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) stack->hash =3D hash; stack->size =3D size; /* stack->handle is already filled in by depot_init_pool(). */ + refcount_set(&stack->count, 1); memcpy(stack->entries, entries, flex_array_size(stack, entries, size)); =20 /* @@ -489,6 +492,8 @@ depot_stack_handle_t stack_depot_save_flags(unsigned lo= ng *entries, /* Fast path: look the stack trace up without full locking. */ found =3D find_stack(bucket, entries, nr_entries, hash); if (found) { + if (depot_flags & STACK_DEPOT_FLAG_GET) + refcount_inc(&found->count); read_unlock_irqrestore(&pool_rwlock, flags); goto exit; } @@ -528,12 +533,15 @@ depot_stack_handle_t stack_depot_save_flags(unsigned = long *entries, list_add(&new->list, bucket); found =3D new; } - } else if (prealloc) { + } else { + if (depot_flags & STACK_DEPOT_FLAG_GET) + refcount_inc(&found->count); /* * Stack depot already contains this stack trace, but let's * keep the preallocated memory for future. */ - depot_keep_new_pool(&prealloc); + if (prealloc) + depot_keep_new_pool(&prealloc); } =20 write_unlock_irqrestore(&pool_rwlock, flags); --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85D7CC197A0 for ; Mon, 20 Nov 2023 17:50:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234710AbjKTRu1 (ORCPT ); Mon, 20 Nov 2023 12:50:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234651AbjKTRtw (ORCPT ); Mon, 20 Nov 2023 12:49:52 -0500 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [IPv6:2001:41d0:1004:224b::aa]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6E621708 for ; Mon, 20 Nov 2023 09:49:42 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502580; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=taQhm6+sqq7C99vuNmST7zKoEFBrlbi2ArfSWbY49ok=; b=DLuotPQZ2ya2ze/Uk9qdks6Velp5g/ufNOpAnZ3F0CTG4bBuTmqBJZX+8HrA4Dqfb+h/XH cXG4e43rc7TxqEGmM94O/sylDTL5wKtysxQVD2NH08lAvJQHMJZz91DKB754x+wRKfj68K mQIu1A/BqCWkTls4JakGGQmnxTCxoCg= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 17/22] lib/stackdepot: allow users to evict stack traces Date: Mon, 20 Nov 2023 18:47:15 +0100 Message-Id: <1d1ad5692ee43d4fc2b3fd9d221331d30b36123f.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Add stack_depot_put, a function that decrements the reference counter on a stack record and removes it from the stack depot once the counter reaches 0. Internally, when removing a stack record, the function unlinks it from the hash table bucket and returns to the freelist. With this change, the users of stack depot can call stack_depot_put when keeping a stack trace in the stack depot is not needed anymore. This allows avoiding polluting the stack depot with irrelevant stack traces and thus have more space to store the relevant ones before the stack depot reaches its capacity. Signed-off-by: Andrey Konovalov --- Changes v1->v2: - Comments fixes as suggested by Marco. - Add lockdep_assert annotation. - Adapt to using list_head's. - Rename stack_depot_evict to stack_depot_put. --- include/linux/stackdepot.h | 14 ++++++++++++++ lib/stackdepot.c | 37 ++++++++++++++++++++++++++++++++++++- 2 files changed, 50 insertions(+), 1 deletion(-) diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index 611716702d73..a6796f178913 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -97,6 +97,8 @@ static inline int stack_depot_early_init(void) { return 0= ; } * * If STACK_DEPOT_FLAG_GET is set in @depot_flags, stack depot will increm= ent * the refcount on the saved stack trace if it already exists in stack dep= ot. + * Users of this flag must also call stack_depot_put() when keeping the st= ack + * trace is no longer required to avoid overflowing the refcount. * * If the provided stack trace comes from the interrupt context, only the = part * up to the interrupt entry is saved. @@ -162,6 +164,18 @@ void stack_depot_print(depot_stack_handle_t stack); int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t siz= e, int spaces); =20 +/** + * stack_depot_put - Drop a reference to a stack trace from stack depot + * + * @handle: Stack depot handle returned from stack_depot_save() + * + * The stack trace is evicted from stack depot once all references to it h= ave + * been dropped (once the number of stack_depot_evict() calls matches the + * number of stack_depot_save_flags() calls with STACK_DEPOT_FLAG_GET set = for + * this stack trace). + */ +void stack_depot_put(depot_stack_handle_t handle); + /** * stack_depot_set_extra_bits - Set extra bits in a stack depot handle * diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 911dee11bf39..c1b31160f4b4 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -394,7 +394,7 @@ static struct stack_record *depot_fetch_stack(depot_sta= ck_handle_t handle) size_t offset =3D parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack; =20 - lockdep_assert_held_read(&pool_rwlock); + lockdep_assert_held(&pool_rwlock); =20 if (parts.pool_index > pools_num) { WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", @@ -410,6 +410,14 @@ static struct stack_record *depot_fetch_stack(depot_st= ack_handle_t handle) return stack; } =20 +/* Links stack into the freelist. */ +static void depot_free_stack(struct stack_record *stack) +{ + lockdep_assert_held_write(&pool_rwlock); + + list_add(&stack->list, &free_stacks); +} + /* Calculates the hash for a stack. */ static inline u32 hash_stack(unsigned long *entries, unsigned int size) { @@ -592,6 +600,33 @@ unsigned int stack_depot_fetch(depot_stack_handle_t ha= ndle, } EXPORT_SYMBOL_GPL(stack_depot_fetch); =20 +void stack_depot_put(depot_stack_handle_t handle) +{ + struct stack_record *stack; + unsigned long flags; + + if (!handle || stack_depot_disabled) + return; + + write_lock_irqsave(&pool_rwlock, flags); + + stack =3D depot_fetch_stack(handle); + if (WARN_ON(!stack)) + goto out; + + if (refcount_dec_and_test(&stack->count)) { + /* Unlink stack from the hash table. */ + list_del(&stack->list); + + /* Free stack. */ + depot_free_stack(stack); + } + +out: + write_unlock_irqrestore(&pool_rwlock, flags); +} +EXPORT_SYMBOL_GPL(stack_depot_put); + void stack_depot_print(depot_stack_handle_t stack) { unsigned long *entries; --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FCABC197A0 for ; Mon, 20 Nov 2023 17:51:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231136AbjKTRvv (ORCPT ); Mon, 20 Nov 2023 12:51:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234261AbjKTRvW (ORCPT ); Mon, 20 Nov 2023 12:51:22 -0500 Received: from out-177.mta1.migadu.com (out-177.mta1.migadu.com [IPv6:2001:41d0:203:375::b1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 07FB5E3 for ; Mon, 20 Nov 2023 09:50:44 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502642; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=h9lSbnFVvjj2GZw0LrViVCVgXWgHHPxOTEIrM79fNvQ=; b=altZ3Y/XI4JhIu5hrnCRXA2Lh0EqKL+D8A/MAbLwDHf+SQx3XdzFWHdK500Z2nrgBAdsMJ CIl8i/FRs6CobGUwDDY8obdvF4axa9Jsyq1WLFLLkkvZ3UoyLWEgpJBac7eWWb07xxbTHj /N4UEr5XJVfvRHr9tfyWkhDs5sCw/8o= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 18/22] kasan: remove atomic accesses to stack ring entries Date: Mon, 20 Nov 2023 18:47:16 +0100 Message-Id: <29f59126d9845c5257b6c29cd7ad113b16f19f47.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Remove the atomic accesses to entry fields in save_stack_info and kasan_complete_mode_report_info for tag-based KASAN modes. These atomics are not required, as the read/write lock prevents the entries from being read (in kasan_complete_mode_report_info) while being written (in save_stack_info) and the try_cmpxchg prevents the same entry from being rewritten (in save_stack_info) in the unlikely case of wrapping during writing. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- Changes v1->v2: - This is a new patch. --- mm/kasan/report_tags.c | 25 +++++++------------------ mm/kasan/tags.c | 13 +++++-------- 2 files changed, 12 insertions(+), 26 deletions(-) diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c index 8b8bfdb3cfdb..78abdcde5da9 100644 --- a/mm/kasan/report_tags.c +++ b/mm/kasan/report_tags.c @@ -31,10 +31,6 @@ void kasan_complete_mode_report_info(struct kasan_report= _info *info) unsigned long flags; u64 pos; struct kasan_stack_ring_entry *entry; - void *ptr; - u32 pid; - depot_stack_handle_t stack; - bool is_free; bool alloc_found =3D false, free_found =3D false; =20 if ((!info->cache || !info->object) && !info->bug_type) { @@ -61,18 +57,11 @@ void kasan_complete_mode_report_info(struct kasan_repor= t_info *info) =20 entry =3D &stack_ring.entries[i % stack_ring.size]; =20 - /* Paired with smp_store_release() in save_stack_info(). */ - ptr =3D (void *)smp_load_acquire(&entry->ptr); - - if (kasan_reset_tag(ptr) !=3D info->object || - get_tag(ptr) !=3D get_tag(info->access_addr)) + if (kasan_reset_tag(entry->ptr) !=3D info->object || + get_tag(entry->ptr) !=3D get_tag(info->access_addr)) continue; =20 - pid =3D READ_ONCE(entry->pid); - stack =3D READ_ONCE(entry->stack); - is_free =3D READ_ONCE(entry->is_free); - - if (is_free) { + if (entry->is_free) { /* * Second free of the same object. * Give up on trying to find the alloc entry. @@ -80,8 +69,8 @@ void kasan_complete_mode_report_info(struct kasan_report_= info *info) if (free_found) break; =20 - info->free_track.pid =3D pid; - info->free_track.stack =3D stack; + info->free_track.pid =3D entry->pid; + info->free_track.stack =3D entry->stack; free_found =3D true; =20 /* @@ -95,8 +84,8 @@ void kasan_complete_mode_report_info(struct kasan_report_= info *info) if (alloc_found) break; =20 - info->alloc_track.pid =3D pid; - info->alloc_track.stack =3D stack; + info->alloc_track.pid =3D entry->pid; + info->alloc_track.stack =3D entry->stack; alloc_found =3D true; =20 /* diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c index 4fd32121b0fd..b6c017e670d8 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -121,15 +121,12 @@ static void save_stack_info(struct kmem_cache *cache,= void *object, if (!try_cmpxchg(&entry->ptr, &old_ptr, STACK_RING_BUSY_PTR)) goto next; /* Busy slot. */ =20 - WRITE_ONCE(entry->size, cache->object_size); - WRITE_ONCE(entry->pid, current->pid); - WRITE_ONCE(entry->stack, stack); - WRITE_ONCE(entry->is_free, is_free); + entry->size =3D cache->object_size; + entry->pid =3D current->pid; + entry->stack =3D stack; + entry->is_free =3D is_free; =20 - /* - * Paired with smp_load_acquire() in kasan_complete_mode_report_info(). - */ - smp_store_release(&entry->ptr, (s64)object); + entry->ptr =3D object; =20 read_unlock_irqrestore(&stack_ring.lock, flags); } --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9628BC197A0 for ; Mon, 20 Nov 2023 17:51:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234151AbjKTRv6 (ORCPT ); Mon, 20 Nov 2023 12:51:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234295AbjKTRvX (ORCPT ); Mon, 20 Nov 2023 12:51:23 -0500 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73EDED45 for ; Mon, 20 Nov 2023 09:50:45 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502643; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uhMrVBrzgAoT1gwViC8KxLkH9OMZhix/uhvoEc70W98=; b=lATFUJLNYsof+QZ6G2sBXsnC9Q+wIKDyc8lFVJDjx9RK2nGA9FoeQs6kQO+6hjM8HBefIP eURADnY2Rf+gcAsebe+mW3WuHxDxbtNbYaSjhKQqLHNAk7mVow4Kb9CTZdG5zssygETF+r BwY3IBxnt51rdnlRs7VhwlO0TNcSVR8= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 19/22] kasan: check object_size in kasan_complete_mode_report_info Date: Mon, 20 Nov 2023 18:47:17 +0100 Message-Id: <68c6948175aadd7e7e7deea61725103d64a4528f.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Check the object size when looking up entries in the stack ring. If the size of the object for which a report is being printed does not match the size of the object for which a stack trace has been saved in the stack ring, the saved stack trace is irrelevant. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- Changes v2->v3: - Added missing "../slab.h" include for accessing a kmem_cache field. Changes v1->v2: - This is a new patch. --- mm/kasan/report_tags.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c index 78abdcde5da9..55154743f915 100644 --- a/mm/kasan/report_tags.c +++ b/mm/kasan/report_tags.c @@ -7,6 +7,7 @@ #include =20 #include "kasan.h" +#include "../slab.h" =20 extern struct kasan_stack_ring stack_ring; =20 @@ -58,7 +59,8 @@ void kasan_complete_mode_report_info(struct kasan_report_= info *info) entry =3D &stack_ring.entries[i % stack_ring.size]; =20 if (kasan_reset_tag(entry->ptr) !=3D info->object || - get_tag(entry->ptr) !=3D get_tag(info->access_addr)) + get_tag(entry->ptr) !=3D get_tag(info->access_addr) || + info->cache->object_size !=3D entry->size) continue; =20 if (entry->is_free) { --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29CBFC2BB3F for ; Mon, 20 Nov 2023 17:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232734AbjKTRvy (ORCPT ); Mon, 20 Nov 2023 12:51:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234384AbjKTRvY (ORCPT ); Mon, 20 Nov 2023 12:51:24 -0500 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10C69D5F for ; Mon, 20 Nov 2023 09:50:45 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502644; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Qc2DDhk7eSddbt2Q3kjJLSbCNGbLZWOl9JsGZF81sG4=; b=SjlBdcCRByh5PrG2MOhc8aFxhKI3iaDpNaxTHUEIaJyLo5jT4ZNFXt6Bt3sd9u50OfOKSg CaLcy9JTN+VHkT3VWRZiUR5iYfkV9u6uxcxdsNTqWTVW/b0iVcXorrCGAHL4XcSBww8rJU PD/hyomJcMBAWfjY4j+0VCD4sMN1M4g= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 20/22] kasan: use stack_depot_put for tag-based modes Date: Mon, 20 Nov 2023 18:47:18 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Make tag-based KASAN modes evict stack traces from the stack depot once they are evicted from the stack ring. Internally, pass STACK_DEPOT_FLAG_GET to stack_depot_save_flags (via kasan_save_stack) to increment the refcount when saving a new entry to stack ring and call stack_depot_put when removing an entry from stack ring. Reviewed-by: Alexander Potapenko Signed-off-by: Andrey Konovalov --- Changes v1->v2: - Adapt to the stack depot API change. - Drop READ_ONCE when reading entry->stack. --- mm/kasan/tags.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c index b6c017e670d8..739ae997463d 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -97,12 +97,13 @@ static void save_stack_info(struct kmem_cache *cache, v= oid *object, gfp_t gfp_flags, bool is_free) { unsigned long flags; - depot_stack_handle_t stack; + depot_stack_handle_t stack, old_stack; u64 pos; struct kasan_stack_ring_entry *entry; void *old_ptr; =20 - stack =3D kasan_save_stack(gfp_flags, STACK_DEPOT_FLAG_CAN_ALLOC); + stack =3D kasan_save_stack(gfp_flags, + STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET); =20 /* * Prevent save_stack_info() from modifying stack ring @@ -121,6 +122,8 @@ static void save_stack_info(struct kmem_cache *cache, v= oid *object, if (!try_cmpxchg(&entry->ptr, &old_ptr, STACK_RING_BUSY_PTR)) goto next; /* Busy slot. */ =20 + old_stack =3D entry->stack; + entry->size =3D cache->object_size; entry->pid =3D current->pid; entry->stack =3D stack; @@ -129,6 +132,9 @@ static void save_stack_info(struct kmem_cache *cache, v= oid *object, entry->ptr =3D object; =20 read_unlock_irqrestore(&stack_ring.lock, flags); + + if (old_stack) + stack_depot_put(old_stack); } =20 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t f= lags) --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 052FAC2BB3F for ; Mon, 20 Nov 2023 17:52:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234252AbjKTRwA (ORCPT ); Mon, 20 Nov 2023 12:52:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234461AbjKTRv0 (ORCPT ); Mon, 20 Nov 2023 12:51:26 -0500 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 919A4D70 for ; Mon, 20 Nov 2023 09:50:46 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502644; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RvoTVlNH/9QJKGjG7ts3ES/7xJIaYyT0JIUdEPtk5OM=; b=DNgy9uYyYrfck71UIDDMmeBlP2Bik/eXdRS59wwnt2UBuC9bsjPHLcrxPmB7E98KHzUlfS OnFiyTSIdvZJFlR6bvb819vsoHa3zDRv09EFK0vHzurXdv2QeiuJeuOu21i9cfXyy/okM9 r0Wi2UF4LVMIbr0H8VW9kEyPJyGdVBE= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 21/22] kasan: use stack_depot_put for Generic mode Date: Mon, 20 Nov 2023 18:47:19 +0100 Message-Id: <5cef104d9b842899489b4054fe8d1339a71acee0.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Evict alloc/free stack traces from the stack depot for Generic KASAN once they are evicted from the quaratine. For auxiliary stack traces, evict the oldest stack trace once a new one is saved (KASAN only keeps references to the last two). Also evict all saved stack traces on krealloc. To avoid double-evicting and mis-evicting stack traces (in case KASAN's metadata was corrupted), reset KASAN's per-object metadata that stores stack depot handles when the object is initialized and when it's evicted from the quarantine. Note that stack_depot_put is no-op if the handle is 0. Reviewed-by: Marco Elver Signed-off-by: Andrey Konovalov --- mm/kasan/common.c | 3 ++- mm/kasan/generic.c | 22 ++++++++++++++++++---- mm/kasan/quarantine.c | 26 ++++++++++++++++++++------ 3 files changed, 40 insertions(+), 11 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 825a0240ec02..b5d8bd26fced 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -50,7 +50,8 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_= flags_t depot_flags) void kasan_set_track(struct kasan_track *track, gfp_t flags) { track->pid =3D current->pid; - track->stack =3D kasan_save_stack(flags, STACK_DEPOT_FLAG_CAN_ALLOC); + track->stack =3D kasan_save_stack(flags, + STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET); } =20 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 5d168c9afb32..50cc519e23f4 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -449,10 +449,14 @@ struct kasan_free_meta *kasan_get_free_meta(struct km= em_cache *cache, void kasan_init_object_meta(struct kmem_cache *cache, const void *object) { struct kasan_alloc_meta *alloc_meta; + struct kasan_free_meta *free_meta; =20 alloc_meta =3D kasan_get_alloc_meta(cache, object); if (alloc_meta) __memset(alloc_meta, 0, sizeof(*alloc_meta)); + free_meta =3D kasan_get_free_meta(cache, object); + if (free_meta) + __memset(free_meta, 0, sizeof(*free_meta)); } =20 size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object) @@ -489,18 +493,20 @@ static void __kasan_record_aux_stack(void *addr, depo= t_flags_t depot_flags) if (!alloc_meta) return; =20 + stack_depot_put(alloc_meta->aux_stack[1]); alloc_meta->aux_stack[1] =3D alloc_meta->aux_stack[0]; alloc_meta->aux_stack[0] =3D kasan_save_stack(0, depot_flags); } =20 void kasan_record_aux_stack(void *addr) { - return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_CAN_ALLOC); + return __kasan_record_aux_stack(addr, + STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET); } =20 void kasan_record_aux_stack_noalloc(void *addr) { - return __kasan_record_aux_stack(addr, 0); + return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_GET); } =20 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t f= lags) @@ -508,8 +514,16 @@ void kasan_save_alloc_info(struct kmem_cache *cache, v= oid *object, gfp_t flags) struct kasan_alloc_meta *alloc_meta; =20 alloc_meta =3D kasan_get_alloc_meta(cache, object); - if (alloc_meta) - kasan_set_track(&alloc_meta->alloc_track, flags); + if (!alloc_meta) + return; + + /* Evict previous stack traces (might exist for krealloc). */ + stack_depot_put(alloc_meta->alloc_track.stack); + stack_depot_put(alloc_meta->aux_stack[0]); + stack_depot_put(alloc_meta->aux_stack[1]); + __memset(alloc_meta, 0, sizeof(*alloc_meta)); + + kasan_set_track(&alloc_meta->alloc_track, flags); } =20 void kasan_save_free_info(struct kmem_cache *cache, void *object) diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c index ca4529156735..265ca2bbe2dd 100644 --- a/mm/kasan/quarantine.c +++ b/mm/kasan/quarantine.c @@ -143,11 +143,22 @@ static void *qlink_to_object(struct qlist_node *qlink= , struct kmem_cache *cache) static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache) { void *object =3D qlink_to_object(qlink, cache); - struct kasan_free_meta *meta =3D kasan_get_free_meta(cache, object); + struct kasan_alloc_meta *alloc_meta =3D kasan_get_alloc_meta(cache, objec= t); + struct kasan_free_meta *free_meta =3D kasan_get_free_meta(cache, object); unsigned long flags; =20 - if (IS_ENABLED(CONFIG_SLAB)) - local_irq_save(flags); + if (alloc_meta) { + stack_depot_put(alloc_meta->alloc_track.stack); + stack_depot_put(alloc_meta->aux_stack[0]); + stack_depot_put(alloc_meta->aux_stack[1]); + __memset(alloc_meta, 0, sizeof(*alloc_meta)); + } + + if (free_meta && + *(u8 *)kasan_mem_to_shadow(object) =3D=3D KASAN_SLAB_FREETRACK) { + stack_depot_put(free_meta->free_track.stack); + free_meta->free_track.stack =3D 0; + } =20 /* * If init_on_free is enabled and KASAN's free metadata is stored in @@ -157,14 +168,17 @@ static void qlink_free(struct qlist_node *qlink, stru= ct kmem_cache *cache) */ if (slab_want_init_on_free(cache) && cache->kasan_info.free_meta_offset =3D=3D 0) - memzero_explicit(meta, sizeof(*meta)); + memzero_explicit(free_meta, sizeof(*free_meta)); =20 /* - * As the object now gets freed from the quarantine, assume that its - * free track is no longer valid. + * As the object now gets freed from the quarantine, + * take note that its free track is no longer exists. */ *(u8 *)kasan_mem_to_shadow(object) =3D KASAN_SLAB_FREE; =20 + if (IS_ENABLED(CONFIG_SLAB)) + local_irq_save(flags); + ___cache_free(cache, object, _THIS_IP_); =20 if (IS_ENABLED(CONFIG_SLAB)) --=20 2.25.1 From nobody Sun Dec 14 01:49:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A278C197A0 for ; Mon, 20 Nov 2023 17:52:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234492AbjKTRwD (ORCPT ); Mon, 20 Nov 2023 12:52:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234457AbjKTRvZ (ORCPT ); Mon, 20 Nov 2023 12:51:25 -0500 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 542FA1988 for ; Mon, 20 Nov 2023 09:50:47 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502645; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mWJyEm6VyaOWhREL8AAhhvtbKxcDTX0iHOdq2I7biaE=; b=WmK6QhekX7FInJyHV2uIR20pRmvpYax2GIBAaZMlPJyA0fa28yyqkU2wHc9EZkcNKhaGVw rpPS5IdkJL5crjQMbxbFNxa8MnpB9QR4IgbAId2GDpPOic2y+TwrC0P2SZxzr/nb1ApKtj eY3o0dSnWGXhfqV2/RcUKsx+woR/BOo= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 22/22] lib/stackdepot: adjust DEPOT_POOLS_CAP for KMSAN Date: Mon, 20 Nov 2023 18:47:20 +0100 Message-Id: <301a115cf7ce8ddb42ef6de9151c2bb76ba728fc.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov KMSAN is frequently used in fuzzing scenarios and thus saves a lot of stack traces. As KMSAN does not support evicting stack traces from the stack depot, the stack depot capacity might be reached quickly with large stack records. Adjust the maximum number of stack depot pools for this case. The average size of a stack trace saved into the stack depot is ~16 frames. Thus, adjust the maximum pools number accordingly to keep the maximum number of stack traces that can be saved into the stack depot similar to the one that was allowed before the stack trace eviction changes. Signed-off-by: Andrey Konovalov --- lib/stackdepot.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index c1b31160f4b4..870cce2f4cbd 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -41,7 +41,17 @@ #define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALI= GN) #define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_OFFSET_BITS - \ STACK_DEPOT_EXTRA_BITS) +#if IS_ENABLED(CONFIG_KMSAN) && CONFIG_STACKDEPOT_MAX_FRAMES >=3D 32 +/* + * KMSAN is frequently used in fuzzing scenarios and thus saves a lot of s= tack + * traces. As KMSAN does not support evicting stack traces from the stack + * depot, the stack depot capacity might be reached quickly with large sta= ck + * records. Adjust the maximum number of stack depot pools for this case. + */ +#define DEPOT_POOLS_CAP (8192 * (CONFIG_STACKDEPOT_MAX_FRAMES / 16)) +#else #define DEPOT_POOLS_CAP 8192 +#endif #define DEPOT_MAX_POOLS \ (((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? \ (1LL << (DEPOT_POOL_INDEX_BITS)) : DEPOT_POOLS_CAP) --=20 2.25.1