From nobody Wed Dec 17 10:05:35 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 795E4C7618E for ; Fri, 21 Apr 2023 10:15:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231315AbjDUKO7 (ORCPT ); Fri, 21 Apr 2023 06:14:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231329AbjDUKOj (ORCPT ); Fri, 21 Apr 2023 06:14:39 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB320A5F0 for ; Fri, 21 Apr 2023 03:14:37 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 53B631FDDC; Fri, 21 Apr 2023 10:14:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1682072076; h=from:from:reply-to: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=NhQ8pvDEDYdK4MH7I174Hpey5DF3W+He8Wm+uYrTkgw=; b=E5cBcBJ0NS1SCMaDeyEpm1IRLZaQHjgK1FAE4SYuJ40GAfoaJ6W70GfGcSsWIk3Xe1hfRe 3PR8N9XM2u1eZB8mD+cvlzlVt4WpBWIskHlztPK4Wi5JFJku1IHWSGEtjMYGHobusXWq96 vn0t7I0G5Y3PGrtKt1u1P76dOI/WrAM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1682072076; h=from:from:reply-to: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=NhQ8pvDEDYdK4MH7I174Hpey5DF3W+He8Wm+uYrTkgw=; b=CWbSShbgBZJ0E617Q6QJQE0QaIJAUC+0i7cKB+O8UWP4cWLAVoqZkpEIGA61IUeWgdD4+D lQ5hqFH6RMS1NrDQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 88D7A1390E; Fri, 21 Apr 2023 10:14:35 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 6KUrHgtiQmRNaAAAMHmgww (envelope-from ); Fri, 21 Apr 2023 10:14:35 +0000 From: Oscar Salvador To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Vlastimil Babka , Eric Dumazet , Waiman Long , Suren Baghdasaryan , Marco Elver , Andrey Konovalov , Alexander Potapenko , Oscar Salvador Subject: [PATCH v4 1/3] lib/stackdepot: Add a refcount field in stack_record Date: Fri, 21 Apr 2023 12:14:13 +0200 Message-Id: <20230421101415.5734-2-osalvador@suse.de> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230421101415.5734-1-osalvador@suse.de> References: <20230421101415.5734-1-osalvador@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" We want to filter out page_owner output and print only those stacks that have been repeated beyond a certain threshold. This gives us the chance to get rid of a lot of noise. In order to do that, we need to keep track of how many repeated stacks (for allocation) do we have, so we add a new refcount_t field in the stack_record struct. Note that this might increase the size of the struct for some architectures. E.g: x86_64 is not affected due to alignment, but x86 32bits might. The alternative would be to have some kind of struct like this: struct track_stacks { struct stack_record *stack; struct track_stacks *next; refcount_t stack_count; But ithat would imply to perform more allocations and glue everything together, which would make the code more complex, so I think that going with a new field in the struct stack_record is good enough. Note that on __set_page_owner_handle(), page_owner->handle is set, and on __reset_page_owner(), page_owner->free_handle is set. We are interested in page_owner->handle, so when __set_page_owner() gets called, we derive the stack_record struct from page_owner->handle, and we increment its refcount_t field; and when __reset_page_owner() gets called, we derive its stack_record from page_owner->handle() and we decrement its refcount_t field. Signed-off-by: Oscar Salvador --- include/linux/stackdepot.h | 8 ++++- lib/stackdepot.c | 72 ++++++++++++++++++++++++++++++++------ mm/kasan/common.c | 3 +- mm/page_owner.c | 13 ++++--- 4 files changed, 79 insertions(+), 17 deletions(-) diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index e58306783d8e..b94d33312839 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -93,7 +93,9 @@ static inline int stack_depot_early_init(void) { return 0= ; } */ depot_stack_handle_t __stack_depot_save(unsigned long *entries, unsigned int nr_entries, - gfp_t gfp_flags, bool can_alloc); + gfp_t gfp_flags, bool can_alloc, + bool counter); +void stack_depot_dec_count(depot_stack_handle_t handle); =20 /** * stack_depot_save - Save a stack trace to stack depot @@ -109,6 +111,10 @@ depot_stack_handle_t __stack_depot_save(unsigned long = *entries, */ depot_stack_handle_t stack_depot_save(unsigned long *entries, unsigned int nr_entries, gfp_t gfp_flags); +depot_stack_handle_t stack_depot_save_action(unsigned long *entries, + unsigned int nr_entries, + gfp_t gfp_flags, + bool counter); =20 /** * stack_depot_fetch - Fetch a stack trace from stack depot diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 036da8e295d1..e99f4ef218ef 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -59,6 +59,7 @@ struct stack_record { u32 hash; /* Hash in the hash table */ u32 size; /* Number of stored frames */ union handle_parts handle; + refcount_t count; /* Number of the same repeated stacks */ unsigned long entries[]; /* Variable-sized array of frames */ }; =20 @@ -304,6 +305,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32= hash, void **prealloc) stack->handle.offset =3D pool_offset >> DEPOT_STACK_ALIGN; stack->handle.valid =3D 1; stack->handle.extra =3D 0; + refcount_set(&stack->count, 1); memcpy(stack->entries, entries, flex_array_size(stack, entries, size)); pool_offset +=3D required_size; =20 @@ -349,9 +351,15 @@ static inline struct stack_record *find_stack(struct s= tack_record *bucket, return NULL; } =20 +static void stack_depot_inc_count(struct stack_record *stack) +{ + refcount_inc(&stack->count); +} + depot_stack_handle_t __stack_depot_save(unsigned long *entries, unsigned int nr_entries, - gfp_t alloc_flags, bool can_alloc) + gfp_t alloc_flags, bool can_alloc, + bool counter) { struct stack_record *found =3D NULL, **bucket; union handle_parts retval =3D { .handle =3D 0 }; @@ -436,8 +444,11 @@ depot_stack_handle_t __stack_depot_save(unsigned long = *entries, /* Stack depot didn't use this memory, free it. */ free_pages((unsigned long)prealloc, DEPOT_POOL_ORDER); } - if (found) + if (found) { retval.handle =3D found->handle.handle; + if (counter) + stack_depot_inc_count(found); + } fast_exit: return retval.handle; } @@ -447,12 +458,20 @@ 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(entries, nr_entries, alloc_flags, true, false); } EXPORT_SYMBOL_GPL(stack_depot_save); =20 -unsigned int stack_depot_fetch(depot_stack_handle_t handle, - unsigned long **entries) +depot_stack_handle_t stack_depot_save_action(unsigned long *entries, + unsigned int nr_entries, + gfp_t alloc_flags, + bool counter) +{ + return __stack_depot_save(entries, nr_entries, alloc_flags, true, counter= ); +} +EXPORT_SYMBOL_GPL(stack_depot_save_action); + +static struct stack_record *stack_depot_getstack(depot_stack_handle_t hand= le) { union handle_parts parts =3D { .handle =3D handle }; /* @@ -464,25 +483,56 @@ unsigned int stack_depot_fetch(depot_stack_handle_t h= andle, size_t offset =3D parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack; =20 - *entries =3D NULL; - if (!handle) - return 0; + if(!handle) + return NULL; =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; + parts.pool_index, pool_index_cached, handle); + return NULL; } pool =3D stack_pools[parts.pool_index]; if (!pool) - return 0; + return NULL; + stack =3D pool + offset; + return stack; +} + +unsigned int stack_depot_fetch(depot_stack_handle_t handle, + unsigned long **entries) +{ + struct stack_record *stack; + + *entries =3D NULL; + if (!handle) + return 0; + + stack =3D stack_depot_getstack(handle); + if (!stack) + return 0; =20 *entries =3D stack->entries; return stack->size; } EXPORT_SYMBOL_GPL(stack_depot_fetch); =20 +void stack_depot_dec_count(depot_stack_handle_t handle) +{ + struct stack_record *stack =3D NULL; + + stack =3D stack_depot_getstack(handle); + if (stack) { + /* + * page_owner creates some stacks via create_dummy_stack(). + * We are not interested in those, so make sure we only decrement + * "valid" stacks. + */ + if (refcount_read(&stack->count) > 1) + refcount_dec(&stack->count); + } +} + void stack_depot_print(depot_stack_handle_t stack) { unsigned long *entries; diff --git a/mm/kasan/common.c b/mm/kasan/common.c index b376a5d055e5..ea0061ea8ae9 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -43,7 +43,8 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags, bool c= an_alloc) 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(entries, nr_entries, flags, can_alloc, + false); } =20 void kasan_set_track(struct kasan_track *track, gfp_t flags) diff --git a/mm/page_owner.c b/mm/page_owner.c index 220cdeddc295..b6637524e442 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -107,7 +107,7 @@ static inline struct page_owner *get_page_owner(struct = page_ext *page_ext) return (void *)page_ext + page_owner_ops.offset; } =20 -static noinline depot_stack_handle_t save_stack(gfp_t flags) +static noinline depot_stack_handle_t save_stack(gfp_t flags, bool counter) { unsigned long entries[PAGE_OWNER_STACK_DEPTH]; depot_stack_handle_t handle; @@ -126,7 +126,7 @@ static noinline depot_stack_handle_t save_stack(gfp_t f= lags) current->in_page_owner =3D 1; =20 nr_entries =3D stack_trace_save(entries, ARRAY_SIZE(entries), 2); - handle =3D stack_depot_save(entries, nr_entries, flags); + handle =3D stack_depot_save_action(entries, nr_entries, flags, counter); if (!handle) handle =3D failure_handle; =20 @@ -139,6 +139,7 @@ void __reset_page_owner(struct page *page, unsigned sho= rt order) int i; struct page_ext *page_ext; depot_stack_handle_t handle; + depot_stack_handle_t alloc_handle; struct page_owner *page_owner; u64 free_ts_nsec =3D local_clock(); =20 @@ -146,7 +147,10 @@ void __reset_page_owner(struct page *page, unsigned sh= ort order) if (unlikely(!page_ext)) return; =20 - handle =3D save_stack(GFP_NOWAIT | __GFP_NOWARN); + page_owner =3D get_page_owner(page_ext); + alloc_handle =3D page_owner->handle; + + handle =3D save_stack(GFP_NOWAIT | __GFP_NOWARN, false); for (i =3D 0; i < (1 << order); i++) { __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); page_owner =3D get_page_owner(page_ext); @@ -155,6 +159,7 @@ void __reset_page_owner(struct page *page, unsigned sho= rt order) page_ext =3D page_ext_next(page_ext); } page_ext_put(page_ext); + stack_depot_dec_count(alloc_handle); } =20 static inline void __set_page_owner_handle(struct page_ext *page_ext, @@ -189,7 +194,7 @@ noinline void __set_page_owner(struct page *page, unsig= ned short order, struct page_ext *page_ext; depot_stack_handle_t handle; =20 - handle =3D save_stack(gfp_mask); + handle =3D save_stack(gfp_mask, true); =20 page_ext =3D page_ext_get(page); if (unlikely(!page_ext)) --=20 2.35.3