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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: [PATCH] mm: remove duplicated vma->vm_flags check when expanding stack Content-Language: en-US To: Andrew Morton , Xiu Jianfeng Cc: Liam.Howlett@oracle.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230906103312.645712-1-xiujianfeng@huaweicloud.com> <20230910142627.0dce42578bfaab7c4c67e316@linux-foundation.org> From: Xiu Jianfeng In-Reply-To: <20230910142627.0dce42578bfaab7c4c67e316@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CM-TRANSID:cCh0CgA3vq67df5k58qfAA--.49340S2 X-Coremail-Antispam: 1UD129KBjvdXoW7Xw1rArW5WrW8Xr47Zw4kCrg_yoWDurcE93 9ruF4xJwsYqFy7Gw4kGa40vr4agF4UJr1fXryruF13Jw1UGr1rXFyqkr9xJFW5tFZrK3s8 Cwn0ya9akw1IqjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUb4xFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2IYs7xG 6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8w A2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j 6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcVAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCYjI0SjxkI62AI1cAE67vI Y487MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI 0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y 0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxV WUJVW8JwCI42IY6xAIw20EY4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8 JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUywZ7UUU UU= X-CM-SenderInfo: x0lxyxpdqiv03j6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: E270320002 X-Stat-Signature: d4sw9jzkah6amx8jjuaubghizorexedp X-HE-Tag: 1694397889-720200 X-HE-Meta: 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 RHaTJy0p pQKIiTXOjHnoam3JIVNc0TLfTGcKGaULPpqY2FFAoJ/iaELwMLlq8/OfGXhAT4xqcWY4xYH2wVe5qBIpHp7rucQT2B7KXAXdTly61Rzz84bFXwOG9Fiuy4gXMrep7IuJcd/PDa+SIM9Qc71+/qRH5uLe9LjQ3pknrcpqjtYOTgCTVsGK6E7R1QDOsdyjPhXSI4VNLiUoIluVMQgSQP3fcAMozZSFTL/HfJsvjlqfBqus/2Osx3HvNcwPicbZ/SxiUMxa1Je5C7368lErpHkO/R5Ovps1K+q17K8lH 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: Hi, On 2023/9/11 5:26, Andrew Morton wrote: > On Wed, 6 Sep 2023 10:33:12 +0000 Xiu Jianfeng wrote: > >> expand_upwards() and expand_downwards() will return -EFAULT if VM_GROWSUP >> or VM_GROWSDOWN is not correctly set in vma->vm_flags, however in >> !CONFIG_STACK_GROWSUP case, expand_stack_locked() returns -EINVAL first >> if !(vma->vm_flags & VM_GROWSDOWN) before calling expand_downwards(), to >> keep the consistency with CONFIG_STACK_GROWSUP case, remove this check. > > What are the user-visible effects of this change? > > Do you believe this fix should be backported into earlier kernel versions? The usages of this function are as bellow: A:fs/exec.c ret = expand_stack_locked(vma, stack_base); if (ret) ret = -EFAULT; or B:mm/memory.c mm/mmap.c if (expand_stack_locked(vma, addr)) return NULL; which means the return value will not propagate to other places, so I believe there is no user-visible effects of this change, and it's unnecessary to backport to earlier versions.