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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1694625355; 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=gAOd+0bdipGa5TwT77P0cix2trL96KYDpIy1afA6aX4=; b=puVK18ovwq5iY1p+xtahLNnbqGMtfLRPDwUGhyhUQSv+gXInLzJ556ocSpipYuAJUi0IMk O/5IT0uIadYTAipofo7r3zp1kwfW+8ahs4/NkRwA7zFRFCmipzk5gZ6+1AqN6CDXnhRBxH zjagfztze/wMDtvIwTVJol/qj+Z7myE= From: andrey.konovalov@linux.dev To: Marco Elver , Alexander Potapenko Cc: Andrey Konovalov , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v2 07/19] lib/stackdepot: rework helpers for depot_alloc_stack Date: Wed, 13 Sep 2023 19:14:32 +0200 Message-Id: In-Reply-To: References: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 9A82F160009 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 7os83yx1qbzr43g9fjw1bqttwwxe5iit X-HE-Tag: 1694625356-712844 X-HE-Meta: U2FsdGVkX18Qcd4cYEwtNd1ATdRUNyI6d3NTJ8nVhZBPqRB4DE6tjV4Rul9KUZMnr568j9WQx2peoI97d96gOe6pvB1/rRU4X5i7Xd11+BcQ8z6rleke8ZWqKeZlSn9+52iC9YobkBQgzFksJJn8MTOwYYZ7o1mhuyalxXCttyWzmexdrNvHD2s0MtIYrRLWqBbNSJ3Oogl9QrYJ7VGhByMIlrAxJ0ngjuQmqP7OUQsKQQjRuesJACbhKxZntdsI/qJSI7v6CNP7uxoZDuyUW6iUTwHoHb1BfEb5Ty84lWJ9whz09He/jg48B8x2/0ERCB2hv9ZIc0ZAoRwoNlC9BOHSv3gdHONlsKoYvmlSqmiMeUu026TRDtgN1masl9oHGucQP3rGXZcFbkwJUicAulCHeOqjeG/E6naXCuw2lfqWwp1a9ayXm7w8m1CJYdAmYcl2/mlMccwVCWpgRgKjmhTRXR7hPCfZjEnlV91VcLzQFCveRDyn0SZKKT79tRXfWd27bq0Jn5kssCswW2rT1U6HYtv81MlrsjjefsIFqn4Qldqigf0hLlPZ+/blDmAmVQTySfzIAmSTLhNH1tQEimXkv1IGCbFvAHSNUwGLcEIGr6qA15ENlJ6XoD9hDjjqO3QotLV+qonuq81fkpaTxvUon9Lbsf47IERtyzftRmRsefomADNx+zMCNf85vPNW9AeXJcnmnoPW9KBSxNB1sJIAzRqvCp8jB0kVjsrKPem+Ynyd5HQ5i/VfaKT+E9ZPiHd67sSHKl2Mepyu5N4yb2G96xyt1bEEKnJU7TwSYxn7HlAv2zDVMmzGsv7DanaNeLMb17CELDCkeUXVT+q4NchCyM/Njw5Mk6thDipEFNqrW4ATFqbWmkMK+cAeWLc+4zd19YHbCpdJKvKpKo3f42o+5yPFNaoCsVAVCHKTjvTWmYlomef3txex25ZYuMPH6VAi1gRccVviibGBeHg JDIsJpBE y2mdsDVWYEg0h+G0cyF3JcTtro/Yw0m/VX504KrN56cogLZrsWwaeAnBZTPbmDZ/ru+8wlM37s3QBPZCq+WPYKTzKhaM3dDL+uTdu8Tu91VuH8CajLjlYbpWN8Zx0NfcEx53Z5U0kHIyofvdA+2VI+MxLsg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 Reviewed-by: Alexander Potapenko --- lib/stackdepot.c | 87 +++++++++++++++++++++++++++--------------------- 1 file changed, 49 insertions(+), 38 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index babd453261f0..e85b658be050 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -219,54 +219,43 @@ int stack_depot_init(void) } EXPORT_SYMBOL_GPL(stack_depot_init); -/* 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. */ if (!next_pool_required) return; - /* Check if the current pool is not yet allocated. */ - if (stack_pools[pool_index] == NULL) { - /* Use the preallocated memory for the current pool. */ - stack_pools[pool_index] = *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] = *prealloc; *prealloc = 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] = *prealloc; - *prealloc = 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); } -/* Allocates a new stack in a stack depot pool. */ -static struct stack_record * -depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) +/* 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 = 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 >= DEPOT_MAX_POOLS)) { WARN_ONCE(1, "Stack depot reached limit capacity"); - return NULL; + return false; } /* @@ -276,9 +265,10 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) */ WRITE_ONCE(pool_index, pool_index + 1); pool_offset = 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. */ @@ -286,9 +276,30 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) smp_store_release(&next_pool_required, 1); } - /* Assign the preallocated memory to a pool if required. */ + /* Check if the current pool is not yet allocated. */ + if (*prealloc && stack_pools[pool_index] == NULL) { + /* Use the preallocated memory for the current pool. */ + stack_pools[pool_index] = *prealloc; + *prealloc = 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 **prealloc) +{ + struct stack_record *stack; + size_t required_size = DEPOT_STACK_RECORD_SIZE; + + /* Update current and next pools if required and possible. */ + if (!depot_update_pools(required_size, prealloc)) + return NULL; /* Check if we have a pool to save the stack trace. */ if (stack_pools[pool_index] == NULL) @@ -322,7 +333,7 @@ static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle) union handle_parts parts = { .handle = handle }; /* * READ_ONCE pairs with potential concurrent write in - * depot_alloc_stack. + * depot_update_pools. */ int pool_index_cached = READ_ONCE(pool_index); void *pool; @@ -421,8 +432,8 @@ 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. * - * smp_load_acquire pairs with smp_store_release in depot_alloc_stack - * and depot_init_pool. + * smp_load_acquire pairs with smp_store_release in depot_update_pools + * and depot_keep_next_pool. */ if (unlikely(can_alloc && smp_load_acquire(&next_pool_required))) { /* @@ -459,7 +470,7 @@ 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); } raw_spin_unlock_irqrestore(&pool_lock, flags);