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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1r17FC-0085bA-Vl; Thu, 09 Nov 2023 15:46:59 +0000 Date: Thu, 9 Nov 2023 15:46:58 +0000 From: Matthew Wilcox To: jeff.xie@linux.dev Cc: akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, vbabka@suse.cz, cl@linux.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, chensong_2000@189.cn, xiehuan09@gmail.com Subject: Re: [RFC][PATCH 3/4] filemap: implement filemap allocate post callback for page_owner Message-ID: References: <20231109032521.392217-1-jeff.xie@linux.dev> <20231109032521.392217-4-jeff.xie@linux.dev> <27f7b8c52e2da5e8003de2226bff181fdc7a7f69@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27f7b8c52e2da5e8003de2226bff181fdc7a7f69@linux.dev> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 7AD7D4000D X-Stat-Signature: yiz4rn7tntq8ee4ursh8pxt1d1nb3k3b X-HE-Tag: 1699544828-993560 X-HE-Meta: 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 098KPTWL SBOTyUHGUjnsDoyGo6+MuGAWbHtlSxUizZpIgCLsF2gd363SAFcf6LAP3RbyLKtjH58vRxqkoo8J6+nK1vxSMncxEAAyP7VAsoKFnNbMBUqfdAAUlDGLJ1z5bAU6Ikpr4XJrHU4CUjwRGxHjQm4az+LElV/eDS4WPupl8+Jy6bWYaWR5F2H/L5fCo17u1dTsZcUxBBKN8XdI4/1vVF16P2k6bjJdTlC+OoyQ5T05KJ9Y6xPuMuRtPIrX4ZYSOYkGzajAoG6pshx4vvjF3HCOhMNrKFoQYCkn6xpaav0bqRXMJ1sGCnVbcxCJUm66dAudXY6Hm 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, Nov 09, 2023 at 03:43:10PM +0000, jeff.xie@linux.dev wrote: > November 9, 2023 at 10:09 PM, "Matthew Wilcox" wrote: > > Why not just walk the rmap directly to find out where it's mapped in > > any process instead of the one which allocated it? > > Since the page_owner's result only shows which PID allocated this page, we only need to obtain the address space of the corresponding process for that PID. But that's probably uninteresting. Consider, eg, a page from libc. That's going to be mapped by hundreds or even thousands of processes. And the one which originally allocated it may well have exited by this point; files often live long past the process that first reads them.