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Fri, 04 Dec 2020 07:11:11 -0800 (PST) Received: from ziepe.ca ([206.223.160.26]) by smtp.gmail.com with ESMTPSA id d16sm5250322qkc.58.2020.12.04.07.11.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Dec 2020 07:11:10 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1klCjl-005uYg-8g; Fri, 04 Dec 2020 11:11:09 -0400 Date: Fri, 4 Dec 2020 11:11:09 -0400 From: Jason Gunthorpe To: Liu Zixian Cc: akpm@linux-foundation.org, linmiaohe@huawei.com, louhongxiang@huawei.com, linux-mm@kvack.org, hushiyuan@huawei.com, stable@vger.kernel.org Subject: Re: [PATCH v2] fix mmap return value when vma is merged after call_mmap() Message-ID: <20201204151109.GA5487@ziepe.ca> References: <20201203085350.22624-1-liuzixian4@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201203085350.22624-1-liuzixian4@huawei.com> 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: On Thu, Dec 03, 2020 at 04:53:50PM +0800, Liu Zixian wrote: > On success, mmap should return the begin address of newly mapped area, > but patch "mm: mmap: merge vma after call_mmap() if possible" > set vm_start of newly merged vma to return value addr. > Users of mmap will get wrong address if vma is merged after call_mmap(). > We fix this by moving the assignment to addr before merging vma. > > Fixes: d70cec898324 ("mm: mmap: merge vma after call_mmap() if possible") > Signed-off-by: Liu Zixian > --- > v2: > We want to do "addr = vma->vm_start;" unconditionally, > so move assignment to addr before if(unlikely) block. > --- > mm/mmap.c | 26 ++++++++++++-------------- > 1 file changed, 12 insertions(+), 14 deletions(-) Reviewed-by: Jason Gunthorpe Jason