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[109.81.83.231]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a7acab233aasm481728766b.8.2024.07.29.02.16.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jul 2024 02:16:12 -0700 (PDT) Date: Mon, 29 Jul 2024 11:16:11 +0200 From: Michal Hocko To: "Zhijian Li (Fujitsu)" Cc: "linux-mm@kvack.org" , Andrew Morton , David Hildenbrand , Oscar Salvador , "linux-kernel@vger.kernel.org" , "Yasunori Gotou (Fujitsu)" Subject: Re: [PATCH RFC] mm: Avoid triggering oom-killer during memory hot-remove operations Message-ID: References: <20240726084456.1309928-1-lizhijian@fujitsu.com> <2ab277af-06ed-41a9-a2b4-91dd1ffce733@fujitsu.com> <264840d7-d770-29a0-7c36-6ede9063d06f@fujitsu.com> <280af822-577f-468b-953f-b70190551b6f@fujitsu.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <280af822-577f-468b-953f-b70190551b6f@fujitsu.com> On Mon 29-07-24 08:53:11, Zhijian Li (Fujitsu) wrote: [...] > >>>> [13853.758192] pagefault_out_of_memory: 4055 callbacks suppressed > >>>> [13853.758243] Huh VM_FAULT_OOM leaked out to the #PF handler. Retrying PF > >>> > >>> This shouldn't really happen and it indicates that some memory > >>> allocation in the pagefault path has failed. > >> > >> May I know if this will cause side effect to other processes. > > > > This eill mean that the #PF handler has failed to allocate memory and > > the VM_FAULT_OOM error has unwound all the way up to the exception > > handler and that will restart the instruction that has caused the #PF. > > > In essence, as long as the process triggering this is not killed or the > > allocation doesn't suceed it will be looping in the #PF path. This > > normally doesn't happen because our allocators do not fail for small > > allocation requests. > > Thanks again for your detailed explanation. > > I think this is acceptable for the process bound to the being removed node, isn't it? It shouldn't be happening really. This is a sign that something doesn't behave properly. E.g. some of the #PF returning VM_FAULT_OOM without calling into the allocator. -- Michal Hocko SUSE Labs