From nobody Sun Dec 14 06:36:56 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 8DD20C83F18 for ; Tue, 29 Aug 2023 17:13:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237701AbjH2RNR (ORCPT ); Tue, 29 Aug 2023 13:13:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237717AbjH2RMw (ORCPT ); Tue, 29 Aug 2023 13:12:52 -0400 Received: from out-244.mta1.migadu.com (out-244.mta1.migadu.com [95.215.58.244]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8FF40CD1 for ; Tue, 29 Aug 2023 10:12:41 -0700 (PDT) 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=1693329160; 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=TBLA9eVhfpPnUCaW6dvoHE+HvIWz4FYhXI+BxxI+EVo=; b=rTza+MTDtXsApdY3UtmvCOQ7kVEgxoogWmU+0/N+/sEo8Jl8pyma+tVj6hbC217kRw1J6E W2W+iu1c4gZpxYAIOpkN1sNFMFS3da9ylVLiov/nqPc0JE4H1dH8MM7fvRWFW9ucQ0eS+L WhjGfi5dKdpIeZyWgv2oUZtl5JJ4KEI= From: andrey.konovalov@linux.dev To: Marco Elver , Alexander Potapenko Cc: Andrey Konovalov , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH 07/15] stackdepot: rework helpers for depot_alloc_stack Date: Tue, 29 Aug 2023 19:11:17 +0200 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 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. Signed-off-by: Andrey Konovalov --- lib/stackdepot.c | 85 +++++++++++++++++++++++++++--------------------- 1 file changed, 48 insertions(+), 37 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 9ae71e1ef1a7..869d520bc690 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -220,11 +220,11 @@ 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. * READ_ONCE is only used to mark the variable as atomic, * there are no concurrent writes. @@ -232,44 +232,33 @@ static void depot_init_pool(void **prealloc) if (!READ_ONCE(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 refences 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 /* @@ -279,9 +268,10 @@ 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. */ @@ -289,9 +279,30 @@ 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) @@ -325,7 +336,7 @@ 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; @@ -425,7 +436,7 @@ 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. + * in depot_update_pools and depot_keep_next_pool. */ if (unlikely(can_alloc && smp_load_acquire(&next_pool_required))) { /* @@ -462,7 +473,7 @@ 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