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c=relaxed/simple; d=linux-foundation.org; s=korg; t=1688328376; bh=ZJnTsXKaN6uYtJh5LC2hJdMySXlUaJO5Zc6GW+BMzyI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=L6ait9MxtGovd3rhKKKGdWJ1Lvcd6cT3sEcMdSOOn2dXu8Fg0QtVVOPzWWBu1SjWv GsFRQmnrdTZToes1uGZhEAVS5g+MBgbepJVXJHjBt+nnnNJPxuvrSV+sG/UtEasu8H O5KHOG9Xj8sy4IBL6h+7zFv+Wa4vCbnGGhIYqSqY= Date: Sun, 2 Jul 2023 13:06:15 -0700 From: Andrew Morton To: "Matthew Wilcox (Oracle)" Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jan Kara , Christoph Hellwig Subject: Re: [PATCH] writeback: Account the number of pages written back Message-Id: <20230702130615.b72616d7f03b3ab4f6fc8dab@linux-foundation.org> In-Reply-To: <20230628185548.981888-1-willy@infradead.org> References: <20230628185548.981888-1-willy@infradead.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 66yrojo1traap57tbgya5zxabptkep9q X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 42D8440010 X-Rspam-User: X-HE-Tag: 1688328378-625701 X-HE-Meta: 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 Fx29OmhI ZV/cECoSM/RCrUfwRD5yXTpiLeN74WgmSTwZvGSQA+Dq1WkhOgdkRbRzL8WMuYrdLJ60vdwu89D0BP4Sfiub/Bdn56rUlmPRZcI4lmct3T5+NYNYkZOVOebNe5toofUzEuHGqRqP62lJPnoyo//uYsrY2+udW3H6lNb0z9kXQIiMq+a6EYYqiBUOh73Im+02duhO5NxKt/Upr9TjGYZQCcImyK1BURBEGIO9oYj7x1Eu9bUEG8ho2zzyEK59irtoQVEFpC4oejhJSV5IpL26fXybx4JK3Tr2qxx3K30oLVsL8OL9o4zdfjRGaSuc2+lRYhJ3devfgBoHj2hjVkQJLryP6sOY2DREA4TVI7OO78esVVksG+cdhtUxJV5jPWKJsSvunbknp7XjzY53TwVrdSykTLHbdjI7/Ik1X 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 Wed, 28 Jun 2023 19:55:48 +0100 "Matthew Wilcox (Oracle)" wrote: > nr_to_write is a count of pages, so we need to decrease it by the number > of pages in the folio we just wrote, not by 1. Most callers specify > either LONG_MAX or 1, so are unaffected, but writeback_sb_inodes() > might end up writing 512x as many pages as it asked for. 512 is a big number, Should we backport this? > Fixes: 793917d997df ("mm/readahead: Add large folio readahead") I'm not seeing how a readahead change messed up writeback accounting?