From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 90AA33D8A for ; Mon, 11 Dec 2023 00:55:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="TXwUOjcf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B89DC433C8; Mon, 11 Dec 2023 00:55:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1702256102; bh=bYtbAW+nC+5Bpp14xa69/8Gj+fZ3TPgh1ciaq2cdlRc=; h=Date:To:From:Subject:From; b=TXwUOjcfIV5hZzpbuDAEGhZKbdqztywCny+/JwBiyrmvC5JqROrcxDpX1cSBQ6PAI D4Vo92vz3AApIprDzaA8vmLcvXV1Drr0qhI/ONB2wPFiJwuSjLvr3HwnqLrMB2bJtt lZwErEL++fv0uB0iR37tmPgrjP0/dfdsiGqTK5cM= Date: Sun, 10 Dec 2023 16:55:01 -0800 To: mm-commits@vger.kernel.org,vbabka@suse.cz,osalvador@suse.de,glider@google.com,eugenis@google.com,elver@google.com,dvyukov@google.com,andreyknvl@google.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] kasan-remove-atomic-accesses-to-stack-ring-entries.patch removed from -mm tree Message-Id: <20231211005502.5B89DC433C8@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: kasan: remove atomic accesses to stack ring entries has been removed from the -mm tree. Its filename was kasan-remove-atomic-accesses-to-stack-ring-entries.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Andrey Konovalov Subject: kasan: remove atomic accesses to stack ring entries Date: Mon, 20 Nov 2023 18:47:16 +0100 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. Link: https://lkml.kernel.org/r/29f59126d9845c5257b6c29cd7ad113b16f19f47.1700502145.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Alexander Potapenko Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Marco Elver Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/kasan/report_tags.c | 25 +++++++------------------ mm/kasan/tags.c | 13 +++++-------- 2 files changed, 12 insertions(+), 26 deletions(-) --- a/mm/kasan/report_tags.c~kasan-remove-atomic-accesses-to-stack-ring-entries +++ a/mm/kasan/report_tags.c @@ -31,10 +31,6 @@ void kasan_complete_mode_report_info(str 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 = false, free_found = false; if ((!info->cache || !info->object) && !info->bug_type) { @@ -61,18 +57,11 @@ void kasan_complete_mode_report_info(str entry = &stack_ring.entries[i % stack_ring.size]; - /* Paired with smp_store_release() in save_stack_info(). */ - ptr = (void *)smp_load_acquire(&entry->ptr); - - if (kasan_reset_tag(ptr) != info->object || - get_tag(ptr) != get_tag(info->access_addr)) + if (kasan_reset_tag(entry->ptr) != info->object || + get_tag(entry->ptr) != get_tag(info->access_addr)) continue; - pid = READ_ONCE(entry->pid); - stack = READ_ONCE(entry->stack); - is_free = 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(str if (free_found) break; - info->free_track.pid = pid; - info->free_track.stack = stack; + info->free_track.pid = entry->pid; + info->free_track.stack = entry->stack; free_found = true; /* @@ -95,8 +84,8 @@ void kasan_complete_mode_report_info(str if (alloc_found) break; - info->alloc_track.pid = pid; - info->alloc_track.stack = stack; + info->alloc_track.pid = entry->pid; + info->alloc_track.stack = entry->stack; alloc_found = true; /* --- a/mm/kasan/tags.c~kasan-remove-atomic-accesses-to-stack-ring-entries +++ a/mm/kasan/tags.c @@ -121,15 +121,12 @@ next: if (!try_cmpxchg(&entry->ptr, &old_ptr, STACK_RING_BUSY_PTR)) goto next; /* Busy slot. */ - 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 = cache->object_size; + entry->pid = current->pid; + entry->stack = stack; + entry->is_free = is_free; - /* - * Paired with smp_load_acquire() in kasan_complete_mode_report_info(). - */ - smp_store_release(&entry->ptr, (s64)object); + entry->ptr = object; read_unlock_irqrestore(&stack_ring.lock, flags); } _ Patches currently in -mm which might be from andreyknvl@google.com are