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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id dm8-20020ad44e28000000b0069b4964460esm1392353qvb.82.2024.04.11.14.46.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Apr 2024 14:46:47 -0700 (PDT) Date: Thu, 11 Apr 2024 17:46:45 -0400 From: Peter Xu To: Matthew Wilcox Cc: "Liam R. Howlett" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Suren Baghdasaryan , Lokesh Gidra , Alistair Popple Subject: Re: [PATCH] mm: Always sanity check anon_vma first for per-vma locks Message-ID: References: <20240410170621.2011171-1-peterx@redhat.com> <20240411171319.almhz23xulg4f7op@revolver> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 2EC3A8000F X-Stat-Signature: xobezem9da43okd5ja37b9twpo8gokyf X-Rspam-User: X-HE-Tag: 1712872011-492004 X-HE-Meta: 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 rOlju4+t YhibsNJSiuqBEA9VLl3rfvEAm1q7yTo878optnhSCQSLv1rt6Kt0QCKdrZgW0zg1DQsViLiJ29nE5uxu4tR0eEaXxnlyZ4EFu6pgLOug0LY/2hXQfp5wJCE4o/UWbdfIwhE9H+fR5TqBJFtiHLPiQBjNkmz+uwb5TicMt2HmrdmZk/voKcJX+R+t5tyerFpXpGXWNJt41dWglc0txYFM+i3UrX30TWFgq4dY1IbEnUNoAFLTqlaNs/H4v1CUwjEtZ869D3GMiyB7hN0GWOdqVS04TTJf//DaNjgGXROqCb25TB0aWuK2AmT2EIEDO3Ur7UUp2Y0EqASsBpmVXtZJ8WVnuc9eYU4B/Nso5702d7XtmjUUQyfdNRTlCIAseewUbrL700fNZc1HGWNzq/v7+lja3Hg== 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 Thu, Apr 11, 2024 at 10:27:56PM +0100, Matthew Wilcox wrote: > On Thu, Apr 11, 2024 at 05:12:02PM -0400, Peter Xu wrote: > > The question is whether that's intended to make it as complicated. For > > example, why don't we check anon_vma for anonymous too later when prepare > > anon_vma, however we do it late for file memory. AFAICT there's nothing > > special with file memory in this case. > > Yes, it's absolutely intended. If anything, anon memory is the special > case that checks up-front. > > Congratulations on adding additional instructions to the common case. > I don't understand why you persist with your nonsense. Please stop. How many instructions it takes for a late RETRY for WRITEs to private file mappings, fallback to mmap_sem? Did you even finish reading the patch at all? -- Peter Xu