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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 B57D8C07542 for ; Mon, 27 May 2019 15:12:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 846A8217F4 for ; Mon, 27 May 2019 15:12:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 846A8217F4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 179836B027E; Mon, 27 May 2019 11:12:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 12AB56B0280; Mon, 27 May 2019 11:12:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F33136B0281; Mon, 27 May 2019 11:12:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ot1-f69.google.com (mail-ot1-f69.google.com [209.85.210.69]) by kanga.kvack.org (Postfix) with ESMTP id C11476B027E for ; Mon, 27 May 2019 11:12:07 -0400 (EDT) Received: by mail-ot1-f69.google.com with SMTP id 72so8908612otv.23 for ; Mon, 27 May 2019 08:12:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :in-reply-to:user-agent; bh=+SwoNYGdL5TJTcjSuNRdZDV3y9fIFV4dZFCT9dM/VBA=; b=ZGGrXWkK0H4a8pSB0hpyJ5DYWenQ+f5Ga/lc+UlgwUt/ADEpvL5i+WF+RhP8OcoFSw MLMqpB37N5PTNK1hagufdk0q6xJixPM6Rl8SIui+hVgPRcJzXZyx2NkHb/5IFXLfTtmG 5/cuICopmcp8E3Lq4TJcEYKYqYDwg8JwH5ZHw/kTBywRT6cq/5G5pzifjITogZNNPeZQ E/GZOzF/Fm8A4n3R5OyZ9Am85QPzdVqP+UKPMEMBQFyZq8hf8GbG4CCA9u6sRTJzC9SW zb2YqHQnW5IRva3u9nO/x1DBXQnCpLZLxXKpGRCU2NkCXfpm0E1CaF+pWk3KhkhchfT6 0GkQ== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of oleg@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=oleg@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com X-Gm-Message-State: APjAAAXYxB7WbW/AEPxoBz35pbADi+VtRWcdRCXVBpamEAPTZrUSW0Ys PBny3DRxbK4btKi7Tf0ZQaCSwzS9IEGfzakViL8fhEHUrdu8DOhHpgiW2as08rFd/dzI1Lt9fOr l2GySpwHOVN1OJ+pjKLan3wfJBXK6/wIBHOeq+Hn5ZeZOA2BQVil6OfSN9yIZw+3G1w== X-Received: by 2002:aca:f002:: with SMTP id o2mr14557150oih.31.1558969927450; Mon, 27 May 2019 08:12:07 -0700 (PDT) X-Google-Smtp-Source: APXvYqzQYi6YUmusdqvglwynmydM/bPF4laIWlMcZSRZ37siPJyDS/3SZ9BGWJug3LcF9K488+3c X-Received: by 2002:aca:f002:: with SMTP id o2mr14557116oih.31.1558969926708; Mon, 27 May 2019 08:12:06 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1558969926; cv=none; d=google.com; s=arc-20160816; b=RHsDAMEtB/wxLxDhPkBtRuCk8ydpKNZ7tYN1I+gKRm4eFzVmYP1Uv+oqg4oUsH0Lmg h6LxN4+EPOoIlStcfpRDeKxnkKvZHQtJQLbBoir7/IjOwGb3O2+dvlQfeEtvLHgeC5ZL jI0XUJqtbI/VT8h2UEKA1z2TuYYK+TJ3ztvcERgU6GOS+6pibgRjIJWWxIKysuzgH5kr XhF7/diG0x58H5PvtkIe6LRAc1OV4I1d2k8kSN00L3l40Za4whk7edG/yYlzGfB7+XYu ORkmO/G5n44c5P+m8GdjJHtch07mHC4oJsJ1tRUyMQL5+81JReMTf2yC0JYRjEYtfC/2 rsTw== 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; bh=+SwoNYGdL5TJTcjSuNRdZDV3y9fIFV4dZFCT9dM/VBA=; b=wV6ALIlJwj1zYpQIsWdiCYE6QKLWfNS1dCLuY/ZncEEu84LIrhggYZTR0C4t4mA0YF PYqAEHrvy4dfvrxx3nJ2+s9dun42Ao/JmJ6dfGLq15gA5aOMaaAuGHMqLFJFZJanxoJf VtuqeV6W7tiX5ZdMeTl/UqBip46ZEGd+lNVUTqqettBcMDzb2s5bXzNm8JQiwNrXCFgZ zR0QiGo+fbX2+nlacVfDay7en+Y/+AiQdXX+eDvxpeHuei4C1W8AhKZ/o/GZBHeDfA8F EFJYOiy0QpZ4U0ewgAyHfGTVEhrDFbEWoq0ZeD1cq2tjSLI73+sYb3nXJuNgjd0kP8nl WUKQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of oleg@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=oleg@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id q23si5877282otk.310.2019.05.27.08.12.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 May 2019 08:12:06 -0700 (PDT) Received-SPF: pass (google.com: domain of oleg@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of oleg@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=oleg@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ECD117FDFA; Mon, 27 May 2019 15:12:05 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.159]) by smtp.corp.redhat.com (Postfix) with SMTP id 2D197608A4; Mon, 27 May 2019 15:12:03 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 27 May 2019 17:12:05 +0200 (CEST) Date: Mon, 27 May 2019 17:12:02 +0200 From: Oleg Nesterov To: Minchan Kim Cc: Andrew Morton , LKML , linux-mm , Michal Hocko , Johannes Weiner , Tim Murray , Joel Fernandes , Suren Baghdasaryan , Daniel Colascione , Shakeel Butt , Sonny Rao , Brian Geffon Subject: Re: [RFC 5/7] mm: introduce external memory hinting API Message-ID: <20190527151201.GB8961@redhat.com> References: <20190520035254.57579-1-minchan@kernel.org> <20190520035254.57579-6-minchan@kernel.org> <20190521153113.GA2235@redhat.com> <20190527074300.GA6879@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190527074300.GA6879@google.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 27 May 2019 15:12:06 +0000 (UTC) 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 05/27, Minchan Kim wrote: > > > another problem is that pid_task(pid) can return a zombie leader, in this case > > mm_access() will fail while it shouldn't. > > I'm sorry. I didn't notice that. However, I couldn't understand your point. > Why do you think mm_access shouldn't fail even though pid_task returns > a zombie leader? The leader can exit (call sys_exit(), not sys_exit_group()), this won't affect other threads. In this case the process is still alive even if the leader thread is zombie. That is why we have find_lock_task_mm(). Oleg.