From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98300C10F13 for ; Thu, 11 Apr 2019 17:05:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 59AB620818 for ; Thu, 11 Apr 2019 17:05:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="qU0c29yC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 59AB620818 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=cmpxchg.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D514B6B026E; Thu, 11 Apr 2019 13:05:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CDBCF6B026F; Thu, 11 Apr 2019 13:05:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B7C516B0270; Thu, 11 Apr 2019 13:05:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-yw1-f69.google.com (mail-yw1-f69.google.com [209.85.161.69]) by kanga.kvack.org (Postfix) with ESMTP id 90A446B026E for ; Thu, 11 Apr 2019 13:05:44 -0400 (EDT) Received: by mail-yw1-f69.google.com with SMTP id s65so4909243ywf.10 for ; Thu, 11 Apr 2019 10:05:44 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=7jjkT3BK3TrD5+yfkCQiasOngzvtZFHArOGePxAfgQY=; b=TDr0nvwXHSxRCjalZcd1znuo17bZkRsN4YS0TkGYjB2OibxLnzpgn9P770SprGaFXw Xq8iye3colupFR/OGq1imtphZdrRu7l5jvNE3qWyoMJIfb83E8yUNlYoaOMhiLxHTYUO j8pNivS7bnGH70zc9C5BGEWOvsOfyi8D/91u26xMf4/K7b7NkY2JPBmL3ZfEfcH2xm5B GIWHLdHhbJ9nq3es27u4u5pvns8ly2eGJyGlFiLIs3L5MEGBPH3tMV9+aYX+bpHNVEO8 iL5r21/3SVVdJOcECV7dQV0OR3GJMlG9Y9iAjBmE72x++netpguTzzu55wBBQGqmZiY2 1WAw== X-Gm-Message-State: APjAAAXQQqDzV2WN4k1nzSa4jc/NaROZrlfLElQi5dsgcukf12rrMVmO yibK5Q5lgUXFMKhY7fBIy3QbHeHENeT0CtAk4Staa25E4KWfzVb35E6VNgWrmZJRkzDcrePGg30 E8WeCJmRAkO6dKnxLxtbN+3OgJFUQjlTaQ0hX4HdTwAFoxLn8YzeBrfzRyS5t9Z9rXw== X-Received: by 2002:a25:3790:: with SMTP id e138mr41012354yba.162.1555002344258; Thu, 11 Apr 2019 10:05:44 -0700 (PDT) X-Received: by 2002:a25:3790:: with SMTP id e138mr41012273yba.162.1555002343448; Thu, 11 Apr 2019 10:05:43 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1555002343; cv=none; d=google.com; s=arc-20160816; b=eEkOHQtx1R8oB8VfV2ZzIR+MQVb1HcX0bJvpZVOeLklm7tHjayAfez1S5Z5uQe1mjR QPeGAfHTGzUbAqmJpbWZb7sVSL4WLjwzvBeIA1pwDPl6hYIL5HBu0xALkOoLBW99xCb4 W/6kkVKAQekye3U1viVVhUIr1Wvqoj6FglzhO2lvSP8Oz2MT7uN2r35AC8N4jbQibEqi l7sTnl8WVVlGd0FgGCPyRM9HAXhqEVXfRa0Uu0f6rEDUzhl/TuOrIVtfvaRsb2KkGgtd vk/qzDcjv46GBaakche63nMy94Q9tdWWy3SfPKIi6Lj0AqLZRFlk1cxBv/uh3+/clPpj bszA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature; bh=7jjkT3BK3TrD5+yfkCQiasOngzvtZFHArOGePxAfgQY=; b=No7lioAJihLPyMJjcrVRjbIistPnfARA+cd2PUeITZrEchhMgyh6orGGzI1C0PuQaZ iaeveGQJ8vRIduPQvg6i0e+bJGHsgsSOpBSGKS/DTJBtwXVSVKaykDZKkblyblH4oaMv 6w+nV4UwJu2KHnVd79pC5MVKlT2RfMqFtBJMpvITBiEW33uANI19NgUgzJMuIHMUv4F0 rzClwFfsT7TFkoOt1SzEoB8vMRQNIn+g6iU4OQxri+BpSIyqvVtn6N+wncjQWGzB1n42 8EiEC4ka7jBkANLMuHqm7o9w6oJPTMD4XPHSw2myLEYW/Af6BGD+Wcq9L0N22KV6Q+j6 diJg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=qU0c29yC; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id 189sor21908291ybi.189.2019.04.11.10.05.43 for (Google Transport Security); Thu, 11 Apr 2019 10:05:43 -0700 (PDT) Received-SPF: pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=qU0c29yC; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=7jjkT3BK3TrD5+yfkCQiasOngzvtZFHArOGePxAfgQY=; b=qU0c29yC3Jj2uhWf//ABSUwx8aGOnQVAOyECPol8iMOkmoVx3rfLlnPdd3abk7ZIrp cBnWLlTqwPlbX1abhPCMls/eFNIMnUkF0DlH2l/IQsX0oCd6JYIEG+PECn1nS6tPnOCt URhwJBR07oEmOXuZrKhyuYUEWY/+PaNLauQKgcppotczYrHtnkwitBMUiCdjhy+5xKXI o5wwWqjLBHPqgWxYJU0rDmT3PWJv+SWGJTH2lxRsPbBRvdYvEluu5WsyoZSNTJ4KuzWN Om7O9RGcwc0wsTPbTuDNdsg2r4/EBvk7VaOXYH8jueQDOkSlPikaepIw1aT4oXZyFcop d9OA== X-Google-Smtp-Source: APXvYqybSGDxqGfs0YDwR/MRKFuproumSYuZA3xfdWLANrwNc6cL+PJzmEZqmBocDRbJxqob5OWAlA== X-Received: by 2002:a25:4e08:: with SMTP id c8mr27714529ybb.339.1555002342830; Thu, 11 Apr 2019 10:05:42 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::3:2a81]) by smtp.gmail.com with ESMTPSA id k125sm24528572ywb.26.2019.04.11.10.05.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 11 Apr 2019 10:05:41 -0700 (PDT) Date: Thu, 11 Apr 2019 13:05:40 -0400 From: Johannes Weiner To: Matthew Wilcox Cc: Suren Baghdasaryan , akpm@linux-foundation.org, mhocko@suse.com, rientjes@google.com, yuzhoujian@didichuxing.com, jrdr.linux@gmail.com, guro@fb.com, penguin-kernel@i-love.sakura.ne.jp, ebiederm@xmission.com, shakeelb@google.com, christian@brauner.io, minchan@kernel.org, timmurray@google.com, dancol@google.com, joel@joelfernandes.org, jannh@google.com, linux-mm@kvack.org, lsf-pc@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [RFC 2/2] signal: extend pidfd_send_signal() to allow expedited process killing Message-ID: <20190411170540.GA5136@cmpxchg.org> References: <20190411014353.113252-1-surenb@google.com> <20190411014353.113252-3-surenb@google.com> <20190411153313.GE22763@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190411153313.GE22763@bombadil.infradead.org> User-Agent: Mutt/1.11.4 (2019-03-13) 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, Apr 11, 2019 at 08:33:13AM -0700, Matthew Wilcox wrote: > On Wed, Apr 10, 2019 at 06:43:53PM -0700, Suren Baghdasaryan wrote: > > Add new SS_EXPEDITE flag to be used when sending SIGKILL via > > pidfd_send_signal() syscall to allow expedited memory reclaim of the > > victim process. The usage of this flag is currently limited to SIGKILL > > signal and only to privileged users. > > What is the downside of doing expedited memory reclaim? ie why not do it > every time a process is going to die? I agree with this. The oom reaper mostly does work the exiting task would have to do anyway, so this shouldn't be measurably more expensive to do it per default. I wouldn't want to add a new interface unless we really do need that type of control.