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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id v23-20020a05620a0a9700b0078ebb13a03csm6315948qkg.67.2024.04.15.06.31.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Apr 2024 06:31:26 -0700 (PDT) Date: Mon, 15 Apr 2024 09:31:24 -0400 From: Peter Xu To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, willy@infradead.org, david@redhat.com, lokeshgidra@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] userfaultfd: remove WRITE_ONCE when setting folio->index during UFFDIO_MOVE Message-ID: References: <20240415020821.1152951-1-surenb@google.com> MIME-Version: 1.0 In-Reply-To: <20240415020821.1152951-1-surenb@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Stat-Signature: uxetkzuhafw117kp1ezm6uq5kn59xkr1 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D6CF91C0011 X-Rspam-User: X-HE-Tag: 1713187890-69440 X-HE-Meta: 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 7tiIIipx 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 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: List-Subscribe: List-Unsubscribe: On Sun, Apr 14, 2024 at 07:08:21PM -0700, Suren Baghdasaryan wrote: > When folio is moved with UFFDIO_MOVE it gets locked before the rmap and > index are modified. Due to the folio lock being already held, WRITE_ONCE() > is not needed when setting the folio index. Remove it. > > Reported-by: Matthew Wilcox > Signed-off-by: Suren Baghdasaryan > Cc: David Hildenbrand > Cc: Peter Xu > Cc: Lokesh Gidra Reviewed-by: Peter Xu -- Peter Xu