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[109.81.28.101]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-3bb7f02578dsm10423195f8f.62.2025.08.17.12.37.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 17 Aug 2025 12:37:28 -0700 (PDT) Date: Sun, 17 Aug 2025 21:37:27 +0200 From: Michal Hocko To: zhongjinji@honor.com Cc: linux-mm@kvack.org, akpm@linux-foundation.org, rientjes@google.com, shakeel.butt@linux.dev, npache@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, peterz@infradead.org, dvhart@infradead.org, dave@stgolabs.net, andrealmeid@igalia.com, liam.howlett@oracle.com, liulu.liu@honor.com, feng.han@honor.com Subject: Re: [PATCH v4 2/3] mm/oom_kill: Only delay OOM reaper for processes using robust futexes Message-ID: References: <20250814135555.17493-1-zhongjinji@honor.com> <20250814135555.17493-3-zhongjinji@honor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250814135555.17493-3-zhongjinji@honor.com> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 8173B40009 X-Stat-Signature: ht9hrpr1s9k75p69f4tn911mcpzxniaf X-Rspam-User: X-HE-Tag: 1755459450-360318 X-HE-Meta: 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 m35XjzQx Je6rGVGfXWep0Xhb950gThtPkIWlInElrM6i+PoMuQPYcDMao8V405J5ks6u86zgJx+4NT/gwvQ0xNZxWSvxPLTQCvLiH8HljXURJNyFGtuFCD7O8Y1yVhAKuzRAkBox7vqtZTzvIe7M2ey2yn0adFYASLHuzxb3Yhm993YlOBWgwz6cKJImVnmhIdgfQHkM4sH1ms1SOMF3LHRR/4eVJOI3GSr5WfzaNHgl4RqvX/6UnrXVnAolG9itrDTcFwArc/GU/E0PlaFPY/dl77z76CJRHZpbB0IiOvlZvBrvt8ZY+9FRrZzWlPDHs+5+vMXSB3ZZEBSoGcju8AIX5tCu3eorMmS3qXG2nNwWSWnGV0ZZiccLqzQ5ygyo1y550xp099icqcmqq3PINduMkNc946DutHwf0J2mRSDyUb4E27BZjsljJDagWyQqPEJ/lyciNTtoqbLcZRytQMdqMRadFFyRDBw== 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 14-08-25 21:55:54, zhongjinji@honor.com wrote: > From: zhongjinji > > The OOM reaper can quickly reap a process's memory when the system encounters > OOM, helping the system recover. Without the OOM reaper, if a process frozen > by cgroup v1 is OOM killed, the victims' memory cannot be freed, and the > system stays in a poor state. Even if the process is not frozen by cgroup v1, > reaping victims' memory is still meaningful, because having one more process > working speeds up memory release. > > When processes holding robust futexes are OOM killed but waiters on those > futexes remain alive, the robust futexes might be reaped before > futex_cleanup() runs. It would cause the waiters to block indefinitely. > To prevent this issue, the OOM reaper's work is delayed by 2 seconds [1]. > The OOM reaper now rarely runs since many killed processes exit within 2 > seconds. > > Because robust futex users are few, it is unreasonable to delay OOM reap for > all victims. For processes that do not hold robust futexes, the OOM reaper > should not be delayed and for processes holding robust futexes, the OOM > reaper must still be delayed to prevent the waiters to block indefinitely [1]. > > Link: https://lore.kernel.org/all/20220414144042.677008-1-npache@redhat.com/T/#u [1] What has happened to https://lore.kernel.org/all/aJGiHyTXS_BqxoK2@tiehlicka/T/#u ? Generally speaking it would be great to provide a link to previous versions of the patchset. I do not see v3 in my inbox (which is quite messy ATM so I might have easily missed it). -- Michal Hocko SUSE Labs