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b=MdoSnqXiyJU9RPogV+Gl9lF5W3zr6ih/WgToqdUmnfZWF8TN8ipZKFOob7P+LYrnl XmhANS8dQv1bStWpdlXf1/8DHqdOz9hIPWvxJJgKq6TTW9KBGUNll6KGz8t7nqy5PV 2pKcsqX4Lfh8PrKHQPI3zqHhcxHAKZtRtKkqJzR8= Date: Thu, 5 Jun 2025 14:51:52 -0700 From: Andrew Morton To: Jan Kara Cc: Chi Zhiling , willy@infradead.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chi Zhiling Subject: Re: [PATCH] readahead: fix return value of page_cache_next_miss() when no hole is found Message-Id: <20250605145152.9ae3edb99f29ef46b30096e4@linux-foundation.org> In-Reply-To: References: <20250605054935.2323451-1-chizhiling@163.com> X-Mailer: Sylpheed 3.7.0 (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-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 6916020009 X-Stat-Signature: sfq3mczwg9ig3z81aopjxkqtx3sn8g9a X-Rspam-User: X-HE-Tag: 1749160314-842093 X-HE-Meta: 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 CSb29bLy YWZQV1jsAVobMEjcedfmn+83SQTjblI49Lh0K23klhixB3Av2m9drsZV9mt8mAl1i1SRx8LK0T2ACwQwJUrNYsLjiWcTpVGzjRDXnpWPabMHNdhRp55EZ9iqLQhytJ2qT9pbm8RQJzXX+145kjjl8+oUXgAeAvfz0k25bNgTHGRcNeVO+1pFJXJG6kEjfLVIUIGAguvOmyQAHvaTkW+jP0XG6NJkAIzVwnXkfTkGP9dQRMHcXmLZSptsgr1VVFujk4XxXmBfxkdnDADaGv92csoW7ZeERoPvXTjI4nJiCfo1jST0= 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, 5 Jun 2025 10:22:23 +0200 Jan Kara wrote: > On Thu 05-06-25 13:49:35, Chi Zhiling wrote: > > From: Chi Zhiling > > > > max_scan in page_cache_next_miss always decreases to zero when no hole > > is found, causing the return value to be index + 0. > > > > Fix this by preserving the max_scan value throughout the loop. > > > > Fixes: 901a269ff3d5 ("filemap: fix page_cache_next_miss() when no hole found") > > Signed-off-by: Chi Zhiling > > Indeed. Thanks for catching this. Don't know how I missed that. Feel free > to add: > > Reviewed-by: Jan Kara > Thanks. It's a simple patch - do we expect it to have significant runtime effects?