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Wed, 04 Aug 2021 09:54:24 -0700 (PDT) MIME-Version: 1.0 References: <20210802221431.2251210-1-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 4 Aug 2021 09:54:12 -0700 Message-ID: Subject: Re: [PATCH v4 1/2] mm: introduce process_mrelease system call To: Michal Hocko Cc: Andrew Morton , David Rientjes , Matthew Wilcox , Johannes Weiner , Roman Gushchin , Rik van Riel , Minchan Kim , Christian Brauner , Christoph Hellwig , Oleg Nesterov , David Hildenbrand , Jann Horn , Shakeel Butt , Andy Lutomirski , Christian Brauner , Florian Weimer , Jan Engelhardt , Tim Murray , Linux API , linux-mm , LKML , kernel-team Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=RPnPRoc8; spf=pass (imf06.hostedemail.com: domain of surenb@google.com designates 209.85.219.175 as permitted sender) smtp.mailfrom=surenb@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 9F5598026F74 X-Stat-Signature: wugjosystzsizyhg9w39ip9xnw8swtiy X-HE-Tag: 1628096065-284516 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: On Tue, Aug 3, 2021 at 11:21 PM Michal Hocko wrote: > > On Tue 03-08-21 15:09:43, Suren Baghdasaryan wrote: > > On Tue, Aug 3, 2021 at 10:27 AM Suren Baghdasaryan wrote: > [...] > > > > > + if (task_will_free_mem(task) && (task->flags & PF_KTHREAD) == 0) { > > > > > + mm = task->mm; > > > > > + mmget(mm); > > > > > + } > > > > > + task_unlock(task); > > > > > + if (!mm) { > > > > > > > > Do we want to treat MMF_OOM_SKIP as a failure? > > > > > > Yeah, I don't think we want to create additional contention if > > > oom-killer is already working on this mm. Should we return EBUSY in > > > this case? Other possible options is ESRCH, indicating that this > > > process is a goner, so don't bother. WDYT? > > > > After considering this some more I think ESRCH would be more > > appropriate. EBUSY might be understood as "I need to retry at a better > > time", which is not what we want here. > > Why cannot we simply return 0 in that case. The work has been done > already by the kernel so why should we tell the caller that there was > something wrong? Ah, you are right. I was under the impression that MMF_OOM_SKIP means oom-killer is reaping the mm, but looks like it means that mm was already reaped. If that's true then I agree, returning 0 is the right move here. Will fix. > > -- > Michal Hocko > SUSE Labs