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Received: from 30.42.98.36(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X.pba0A_1774665517 cluster:ay36) by smtp.aliyun-inc.com; Sat, 28 Mar 2026 10:38:38 +0800 Message-ID: Date: Sat, 28 Mar 2026 10:38:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: vmscan: fix dirty folios throttling on cgroup v1 for MGLRU To: Andrew Morton Cc: hannes@cmpxchg.org, david@kernel.org, mhocko@kernel.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, ljs@kernel.org, baohua@kernel.org, kasong@tencent.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <3445af0f09e8ca945492e052e82594f8c4f2e2f6.1774606060.git.baolin.wang@linux.alibaba.com> <20260327083042.da4fd1586ab8aa2f639393b0@linux-foundation.org> From: Baolin Wang In-Reply-To: <20260327083042.da4fd1586ab8aa2f639393b0@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: E57A51C0007 X-Stat-Signature: 5ioy9rp54k1ut7ty6ygx34ijnbr4b1or X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1774665521-50732 X-HE-Meta: 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 UngXi4Za D8hwTLBHDOxdmme+d9r9wk2IFhciFauRD/XBotujwio0Jw85xEu/6BWmUFQSVtJWbZIxC9yuiuHEog5FViURkspirSwPNa9myt6LaHK/UEmhuTi/yAYjVEIiz+4cIGIBnVldjhgow1apuBnXF3W6NYTTLEnJ8RuJl/FfI6rsK4UX8w5GsuMc1Ibg0DsiTHwqE3bA5gQljf2gaL0Qyz3PjV5bL6DmLDNICHixAOnB9VSz1M3r4u0su6vdjkoYgqlCKA+quNxsrm5u5aMH8uYE8HtXoKQcpm9G8WLJbLJlsGbG/hlg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/27/26 11:30 PM, Andrew Morton wrote: > On Fri, 27 Mar 2026 18:21:08 +0800 Baolin Wang wrote: > >> The balance_dirty_pages() won't do the dirty folios throttling on cgroupv1. >> See commit 9badce000e2c ("cgroup, writeback: don't enable cgroup writeback >> on traditional hierarchies"). >> >> Moreover, after commit 6b0dfabb3555 ("fs: Remove aops->writepage"), we no >> longer attempt to write back filesystem folios through reclaim. >> >> On large memory systems, the flusher may not be able to write back quickly >> enough. Consequently, MGLRU will encounter many folios that are already >> under writeback. Since we cannot reclaim these dirty folios, the system >> may run out of memory and trigger the OOM killer. >> >> Hence, for cgroup v1, let's throttle reclaim after waking up the flusher, >> which is similar to commit 81a70c21d917 ("mm/cgroup/reclaim: fix dirty >> pages throttling on cgroup v1"), to avoid unnecessary OOM. >> >> The following test program can easily reproduce the OOM issue. With this patch >> applied, the test passes successfully. >> >> $mkdir /sys/fs/cgroup/memory/test >> $echo 256M > /sys/fs/cgroup/memory/test/memory.limit_in_bytes >> $echo $$ > /sys/fs/cgroup/memory/test/cgroup.procs >> $dd if=/dev/zero of=/mnt/data.bin bs=1M count=800 >> >> Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") > > 3+ years ago, I don't see a need to rush this into 7.0. Agree. > But should we cc:stable? I don't think it's necessary. The issue isn't that serious:)