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[109.81.31.43]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-3cf276d5816sm30579447f8f.25.2025.09.05.02.20.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Sep 2025 02:20:33 -0700 (PDT) Date: Fri, 5 Sep 2025 11:20:33 +0200 From: Michal Hocko To: "Liam R. Howlett" Cc: zhongjinji , rientjes@google.com, shakeel.butt@linux.dev, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, lorenzo.stoakes@oracle.com, surenb@google.com, liulu.liu@honor.com, feng.han@honor.com Subject: Re: [PATCH v7 2/2] mm/oom_kill: The OOM reaper traverses the VMA maple tree in reverse order Message-ID: References: <20250903092729.10611-1-zhongjinji@honor.com> <20250903092729.10611-3-zhongjinji@honor.com> <7rvwvuifkav5oz4ftfuziq23wek2bn6ygvrfotpaweypuy7obv@hjuf3eknscii> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 82351180003 X-Stat-Signature: 1pnynj88xqoe71odwounxosneb8gotju X-Rspam-User: X-HE-Tag: 1757064035-465559 X-HE-Meta: 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 PyPIP4qg KOYQkatNcGlNKyomcsZ+A31oBrBGocnWJ9ZLaP/1aCY9+vWq/dDxznIuhyMoV9bjwKiMv3swvZ/JHh97SDYRuClmaxMfy+TBz5taoulNqbwKJE1O4FIRu0rDhbWwc6gyx8ubzhU2j2+OyAltB4yELHgEOqs6XUZgw5ZrZFUhfIUhXzjx0JmUB8s9SZRzId0eUoB8NgDgwWZptmDUm/5GwOtjFjOO9Fy+CQwZykuQkR3ET5fDR6DgoulmMoM82AHPZI4L1gaWm5IPts1H2zh/v+Gb0/1jpOESf1U7C50EcyvGzY0EmGbl2FcjoQ2fwFmC3TnoseJgopDsK5Yt0XE4Z/T8tRsGxr61dWmeIbkVbmqzyvLFGlA/6yJZe9cZrOXPl1dwWKl9h+qEz3O/eY+OuVYmk9nMPxQ+qm7MhJNskx+jHtgs= 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 04-09-25 22:12:48, Liam R. Howlett wrote: > * Michal Hocko [250904 08:21]: > > On Wed 03-09-25 15:02:34, Liam R. Howlett wrote: > > > * Michal Hocko [250903 08:58]: > > > > On Wed 03-09-25 17:27:29, zhongjinji wrote: > > [...] > > > mmu_notifier_release(mm) is called early in the exit_mmap() path should > > > cause the mmu notifiers to be non-blocking (according to the comment in > > > v6.0 source of exit_mmap [1]. > > > > I am not sure I follow you here. How does this relate to the actual > > direction of the address space freeing? > > It doesn't relate to the direction of the address freeing, I think it > explains the perf data a bit. > > The exit_mmap() would have a decrease in mmu related work while this > thread will have an increase, I think. > > If they race, this thread gets virtually nothing while exit does all of > the work. If they don't race then the work is split. > > Does that make sense? OK, I can see what you mean now. Thanks! I believe we need more data to understand what is actually going on here. Having the overall duration should help to get that. -- Michal Hocko SUSE Labs