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Received: from 30.74.144.138(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X0atlpk_1775543232 cluster:ay36) by smtp.aliyun-inc.com; Tue, 07 Apr 2026 14:27:12 +0800 Message-ID: Date: Tue, 7 Apr 2026 14:27:11 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 14/14] mm/vmscan: unify writeback reclaim statistic and throttling To: kasong@tencent.com, linux-mm@kvack.org Cc: Andrew Morton , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Barry Song , David Stevens , Chen Ridong , Leno Hou , Yafang Shao , Yu Zhao , Zicheng Wang , Kalesh Singh , Suren Baghdasaryan , Chris Li , Vernon Yang , linux-kernel@vger.kernel.org, Qi Zheng References: <20260403-mglru-reclaim-v3-0-a285efd6ff91@tencent.com> <20260403-mglru-reclaim-v3-14-a285efd6ff91@tencent.com> From: Baolin Wang In-Reply-To: <20260403-mglru-reclaim-v3-14-a285efd6ff91@tencent.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: A518110000B X-Stat-Signature: uft7r8zudsjr9kf8xtfzmmu6grzyi799 X-Rspamd-Server: rspam06 X-HE-Tag: 1775543237-676244 X-HE-Meta: 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 rrR87qlR f5Z4g4AdMYPIsqmCH1UE+IVmyliSCsn+0fysqmfYvHvuv/SRsY4K7mmj7LItcq0KeBxN6Xn/QY5n0Qh27VeR9Kz5nxGL+yxx7XU9OJEjYKrcLORvPXqYyq3rPRuKTi0M+utGoW57Jrw/5CvS7EdcKXHpYOXMr6JWj0TfrIMOQ7aH5pv8HansxLQBxY7G7a+zRMAZ8SUmaXWG1EAVMzpa3CQGX3Fx0xv9/iHwHJ/OGIDugEp2Vw37vEhpCNtI+wOMNj+QHk0Le/Lj7BikubtxDPtZVqVv432WW+XBqTnJXIe2ZWQ8XWm3m0Q7byR9vTLIMk7/0f3QfO+AnxlidKeXmJV9I7RpcY1rYTTtkB/YDILqtTkPMrAl0Lqm3BJKv6UQHjBDlWNMM4gzD6WSKYEvBC10p+7wkUHWK/m/4b362bjvp8E8bYoz2yj2U/7x9ousvBjT2 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/3/26 2:53 AM, Kairui Song via B4 Relay wrote: > From: Kairui Song > > Currently MGLRU and non-MGLRU handle the reclaim statistic and > writeback handling very differently, especially throttling. > Basically MGLRU just ignored the throttling part. > > Let's just unify this part, use a helper to deduplicate the code > so both setups will share the same behavior. > > Test using following reproducer using bash: > > echo "Setup a slow device using dm delay" > dd if=/dev/zero of=/var/tmp/backing bs=1M count=2048 > LOOP=$(losetup --show -f /var/tmp/backing) > mkfs.ext4 -q $LOOP > echo "0 $(blockdev --getsz $LOOP) delay $LOOP 0 0 $LOOP 0 1000" | \ > dmsetup create slow_dev > mkdir -p /mnt/slow && mount /dev/mapper/slow_dev /mnt/slow > > echo "Start writeback pressure" > sync && echo 3 > /proc/sys/vm/drop_caches > mkdir /sys/fs/cgroup/test_wb > echo 128M > /sys/fs/cgroup/test_wb/memory.max > (echo $BASHPID > /sys/fs/cgroup/test_wb/cgroup.procs && \ > dd if=/dev/zero of=/mnt/slow/testfile bs=1M count=192) > > echo "Clean up" > echo "0 $(blockdev --getsz $LOOP) error" | dmsetup load slow_dev > dmsetup resume slow_dev > umount -l /mnt/slow && sync > dmsetup remove slow_dev > > Before this commit, `dd` will get OOM killed immediately if > MGLRU is enabled. Classic LRU is fine. > > After this commit, throttling is now effective and no more spin on > LRU or premature OOM. Stress test on other workloads also looking good. > > Global throttling is not here yet, we will fix that separately later. > > Suggested-by: Chen Ridong > Tested-by: Leno Hou > Signed-off-by: Kairui Song > --- LGTM. Reviewed-by: Baolin Wang