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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rVXVq-0000000Fxpf-31Gt; Thu, 01 Feb 2024 13:53:54 +0000 Date: Thu, 1 Feb 2024 13:53:54 +0000 From: Matthew Wilcox To: Jan Kara Cc: Liu Shixin , Alexander Viro , Christian Brauner , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] mm/readahead: stop readahead loop if memcg charge fails Message-ID: References: <20240201100835.1626685-1-liushixin2@huawei.com> <20240201100835.1626685-2-liushixin2@huawei.com> <20240201135231.tgnn7cnlmtqh5n4f@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240201135231.tgnn7cnlmtqh5n4f@quack3> X-Rspamd-Queue-Id: B010740017 X-Rspam-User: X-Stat-Signature: 8tp6zntyd83nm797e5bdgx148crk1jqu X-Rspamd-Server: rspam03 X-HE-Tag: 1706795637-458525 X-HE-Meta: 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 yTtjLUD/ FRP/l8QyLUF2UaqBsInOpRxBJoAg7mb4oIRFSIzvYh0VH93aqLeq3VYizW04rozdab3v+v/XsCQt8cckfUnbQdpQJQxxtXShBoCIDb3yJcqY4STjy2eDf4w6/Gxh2t7fxDjtBuwCLXbRv4VY= 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, Feb 01, 2024 at 02:52:31PM +0100, Jan Kara wrote: > On Thu 01-02-24 13:47:03, Matthew Wilcox wrote: > > On Thu, Feb 01, 2024 at 06:08:34PM +0800, Liu Shixin wrote: > > > @@ -247,9 +248,12 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, > > > folio = filemap_alloc_folio(gfp_mask, 0); > > > if (!folio) > > > break; > > > - if (filemap_add_folio(mapping, folio, index + i, > > > - gfp_mask) < 0) { > > > + > > > + ret = filemap_add_folio(mapping, folio, index + i, gfp_mask); > > > + if (ret < 0) { > > > folio_put(folio); > > > + if (ret == -ENOMEM) > > > + break; > > > > No, that's too early. You've still got a batch of pages which were > > successfully added; you have to read them. You were only off by one > > line though ;-) > > There's a read_pages() call just outside of the loop so this break is > actually fine AFAICT. Oh, good point! I withdraw my criticism.