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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <280af822-577f-468b-953f-b70190551b6f@fujitsu.com> X-Rspamd-Queue-Id: EFF4DC000F X-Stat-Signature: 8opi1rszdfjxsn7x73ht9taab38p977z X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1722244573-541734 X-HE-Meta: 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 U9HCrPxW RT1PKuwHi/4ByS+pupafTghD0CcQ+7USlTuX65cPQUbJ1RzqvksOkZiyROTnS5CrdeQYjz7D0QGH2bYFfjh6XeTFNo0CmartFOn0gMP2XNX7StmAN5n1j2fDrSdP7aQQEdchCMX6QIg4PyGm9Ku9wIbHPUzrpFYvWRrW6FoieYviiluchnwOEwD1k9UZzuVFTdp/qygDp4wYKcnGrV3Ix+EOg+DDrQVVy5+249LslauaQF/Y1mphlWwrwDiuEDlUmMMSR0Dw5LEnkAvEEZop7Ukb3T5tJaJQWnYtkj8rkSStV4jk5B3nILN1KHJ1dzj0cwhin50tPIx+WIo4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.189470, 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 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