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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1wHQsV-00000002Vp4-3mzc; Mon, 27 Apr 2026 18:40:19 +0000 Date: Mon, 27 Apr 2026 19:40:19 +0100 From: Matthew Wilcox To: fujunjie Cc: Jan Kara , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Roman Gushchin , Haoran Zhu Subject: Re: [PATCH v2 1/2] mm/filemap: count only the faulting address as a mmap hit Message-ID: References: <20260427165751.746502-1-fujunjie1@qq.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6E84680008 X-Stat-Signature: ec8wrytdzpi9ejstffzugikqcraje5a8 X-Rspam-User: X-HE-Tag: 1777315226-984622 X-HE-Meta: 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 znvIrpii RG7/6sKBu4+PLAVb3ySry1aoWd5ETUIa5VSnnJNi2/Itf/gnA7MamGSAAeT8AJq04vQLn+qyzGf4A9N3aA3AGWvYxEEGZfUBP0KYMZa6V/ikuyVIus27JIHrS2ZDFsv646cQC8+2WFp/gAs00BO1iaRyvHSfIbM6yhlYiFo7QotYawL/F2PvK2nLsGGSor0IDFpix3RM1sisEpL8DD70oEwVqPGW+cdIvrqI/OUGh9eBZi6W1jruwRuWa0w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 27, 2026 at 04:57:50PM +0000, fujunjie wrote: > - /* > - * If there are too many folios that are recently evicted > - * in a file, they will probably continue to be evicted. > - * In such situation, read-ahead is only a waste of IO. > - * Don't decrease mmap_miss in this scenario to make sure > - * we can stop read-ahead. > - */ I'm sad to lose this comment. Why not move it to ... > + ret |= map_ret; here? > + if ((map_ret & VM_FAULT_NOPAGE) && > + !folio_test_workingset(folio)) { > + unsigned short mmap_miss; > + > + mmap_miss = READ_ONCE(file->f_ra.mmap_miss); > + if (mmap_miss) > + WRITE_ONCE(file->f_ra.mmap_miss, > + mmap_miss - 1); > + }