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b=VnHp71OOB067JG7d/fmPHYeUJRis3eMVKaLYVmMEjYo7GD625bLIh4uCnV98wUeeq dqaksTcQ9OWhYNH8B3QLdR3mVyw6rU1RSoI/LOp1dLixanVlNn/bniuVSf18q2YM7q UW91pAtLy7VfGwZI9Y3iNmrQwYvcgE7rIa/mgZYs= Date: Mon, 7 Oct 2024 19:15:34 -0700 From: Andrew Morton To: Jingxiang Zeng Cc: linux-mm@kvack.org, kasong@tencent.com, linuszeng@tencent.com, linux-kernel@vger.kernel.org, tjmercier@google.com, weixugc@google.com, yuzhao@google.com, chrisl@kernel.org Subject: Re: [RESEND][PATCH v4] mm/vmscan: wake up flushers conditionally to avoid cgroup OOM Message-Id: <20241007191534.ceb663de5ac7ee3695a162a2@linux-foundation.org> In-Reply-To: <20241008015635.2782751-1-jingxiangzeng.cas@gmail.com> References: <20241008015635.2782751-1-jingxiangzeng.cas@gmail.com> 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-Rspamd-Queue-Id: 80065140005 X-Stat-Signature: xfzygqowpkmhhz15omr4ow75pdzesn5p X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1728353736-220077 X-HE-Meta: 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 9A5nNnfE uZz+2PkhDxQfLmfd8MIFty4T4+9JYxWyJC0TYot3UVrEdNMNoheVeswS3hyPT4GFP1SngYrgld3yAqdvxtJcKkfEJACJ3no5cZ+ZOuTHb4BTeNzqmKPEX9skXfkNUa0O7x2mDOnhsrnrGfhkkyMlqO+1nitd6xE9b2xOay60ICnkU3RFlCb4RY7ncGLDs9Wz62T9EhBd6sYKT4KB2RbWVRvUUR/0r0SoLHtG5YyMP89xEHiqAgIjYU3FQnv3ZqM5953UH/v1j+iVAhwTBxNvUBniTSM1LDfLwT4psXrnXUUWAC7SzovVgmJcvasdZnkYZmdnhCMIXkbWRzOqldvbbb69X5D4XBO4SVkIYjB5tX0ZCK68= 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 Tue, 8 Oct 2024 09:56:35 +0800 Jingxiang Zeng wrote: > From: Jingxiang Zeng > > Commit 14aa8b2d5c2e ("mm/mglru: don't sync disk for each aging cycle") > removed the opportunity to wake up flushers during the MGLRU page > reclamation process can lead to an increased likelihood of triggering OOM > when encountering many dirty pages during reclamation on MGLRU. > > This leads to premature OOM if there are too many dirty pages in cgroup: > > ... > > The flusher wake up was removed to decrease SSD wearing, but if we are > seeing all dirty folios at the tail of an LRU, not waking up the flusher > could lead to thrashing easily. So wake it up when a mem cgroups is about > to OOM due to dirty caches. > Thanks for persisting. This patch has a somewhat difficult past and not a lot of review. I'll await feedback from other MGLRU developers before proceeding.