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Fri, 06 Aug 2021 02:23:28 -0700 (PDT) MIME-Version: 1.0 References: <20210805170859.2389276-1-surenb@google.com> In-Reply-To: From: Shakeel Butt Date: Fri, 6 Aug 2021 02:23:17 -0700 Message-ID: Subject: Re: [PATCH v7 1/2] mm: introduce process_mrelease system call To: Michal Hocko Cc: Suren Baghdasaryan , 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 , 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: imf05.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b="cGHj/WVq"; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf05.hostedemail.com: domain of shakeelb@google.com designates 209.85.167.46 as permitted sender) smtp.mailfrom=shakeelb@google.com X-Stat-Signature: hidbnb3q53dmx9hg9u5kawsm54oyb5ng X-Rspamd-Queue-Id: 52BF05021EC4 X-Rspamd-Server: rspam01 X-HE-Tag: 1628241810-901302 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 Thu, Aug 5, 2021 at 11:40 PM Michal Hocko wrote: > [...] > I think you really want something like this: > > if (flags) > return -EINVAL; > > pid = pidfd_get_pid(fd, &f_flags); > if (IS_ERR(pid)) > return PTR_ERR(pid); > task = get_pid_task(pid, PIDTYPE_PID); > if (!task) { > ret = -ESRCH; > goto put_pid; > } > > /* > * Make sure to chose a thread which still has a reference to mm > * during the group exit > */ > p = find_lock_task_mm(task); > if (!p) { > ret = -ESRCH; > goto put_task; > } > > mm = task->mm; mm = p->mm; > mmgrab(mm); > reap = true; > /* If the work has been done already, just exit with success */ > if (test_bit(MMF_OOM_SKIP, &mm->flags)) { > reap = false; > } else if (!task_will_free_mem(p)) { > reap = false; > ret = -EINVAL; > } > task_unlock(p); > > if (!reap) > goto dropmm;; > > /* Do the work*/ > > > dropmm: > mmdrop(mm); > put_task: > put_task(task); > put_pid: > put_pid(pid); > > return ret; > > -- > Michal Hocko > SUSE Labs