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Fri, 29 Aug 2025 04:44:42 -0700 (PDT) Received: from [192.168.1.140] ([85.235.12.238]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-55f67a4c612sm581162e87.146.2025.08.29.04.44.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Aug 2025 04:44:42 -0700 (PDT) From: Linus Walleij Date: Fri, 29 Aug 2025 13:44:40 +0200 Subject: [PATCH 1/2] fork: check charging success before zeroing stack Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250829-fork-cleanups-for-dynstack-v1-1-3bbaadce1f00@linaro.org> References: <20250829-fork-cleanups-for-dynstack-v1-0-3bbaadce1f00@linaro.org> In-Reply-To: <20250829-fork-cleanups-for-dynstack-v1-0-3bbaadce1f00@linaro.org> To: Andrew Morton , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Kees Cook , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Pasha Tatashin Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Walleij X-Mailer: b4 0.14.2 From: Pasha Tatashin No need to do zero cached stack if memcg charge fails, so move the charging attempt before the memset operation. Signed-off-by: Pasha Tatashin Link: https://lore.kernel.org/20240311164638.2015063-6-pasha.tatashin@soleen.com Signed-off-by: Linus Walleij --- kernel/fork.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index af673856499dcaa35e135a9e8042ef28d5c5370d..2a5b7a5fa09b1f3a42473cf44a1316ec8b3b31d0 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -290,6 +290,11 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node) if (!vm_area) continue; + if (memcg_charge_kernel_stack(vm_area)) { + vfree(vm_area->addr); + return -ENOMEM; + } + /* Reset stack metadata. */ kasan_unpoison_range(vm_area->addr, THREAD_SIZE); @@ -298,11 +303,6 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node) /* Clear stale pointers from reused stack. */ memset(stack, 0, THREAD_SIZE); - if (memcg_charge_kernel_stack(vm_area)) { - vfree(vm_area->addr); - return -ENOMEM; - } - tsk->stack_vm_area = vm_area; tsk->stack = stack; return 0; -- 2.50.1