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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1077C433EF for ; Fri, 4 Mar 2022 12:17:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7A0318D0002; Fri, 4 Mar 2022 07:17:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 74EE88D0001; Fri, 4 Mar 2022 07:17:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63E7B8D0002; Fri, 4 Mar 2022 07:17:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0138.hostedemail.com [216.40.44.138]) by kanga.kvack.org (Postfix) with ESMTP id 547898D0001 for ; Fri, 4 Mar 2022 07:17:35 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 01D5998C2F for ; Fri, 4 Mar 2022 12:17:35 +0000 (UTC) X-FDA: 79206604470.22.2A95495 Received: from mail-yw1-f181.google.com (mail-yw1-f181.google.com [209.85.128.181]) by imf15.hostedemail.com (Postfix) with ESMTP id 59EB1A0010 for ; Fri, 4 Mar 2022 12:17:34 +0000 (UTC) Received: by mail-yw1-f181.google.com with SMTP id 00721157ae682-2db569555d6so89029627b3.12 for ; Fri, 04 Mar 2022 04:17:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0GYenn+rgMznVgcu77L9eTvFUbKZ98vSsnayTEi/3mg=; b=zDewUWU4/9EvtfgumVR2lIuAPqJGxbcH3EorBfbMS4fIwHrlv1lpQPKZSYFHj8lSX/ ywTuR3j24MGPFD1AoQuMKPsM+5bGRyxYbGEc/rOko2iF5FdROeiCj4ZT2sdZhIK89TQN My34qhOBFqgYJts0PV5FlBt1LvNCEe5fSlskyZ6Zq8Wq+oaHBxM2H3pOUBYCeaBP8bdo FUDPeXJu++62THA8/Cg6iaZWelLWi0LXvY6u70yQEMq7mWJKFwdB+fD007aOS1NfkUBb rLsvFqBWgL7bbvtAwjTfMBHHlq91KB4oozt5++aRfJeg3fFRnKGcD3v10TWDxPDxEMxF P5FQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0GYenn+rgMznVgcu77L9eTvFUbKZ98vSsnayTEi/3mg=; b=ebm62keCfbq9zuLCCd7OQnr1oZUfe1BkYqp+2E4/fwfWk0qa/ZqDWFiGmzn+o7C2GP iOBKg6Zz7ZGKlGFDwHGFF+CK3w0nAwd5jpi7pMTR2mcefkZJL5RFX+xtDzZmjy9hgRrW DTXPoPF6jDGyhpP7zD8SerBzLHYvNJeRydwJEwTuOzgEQeICvQrVHylXSfAp0IBvqrII E4gQYRr44Ymnq7Y6rpeHIYVGv+yKAB52rIUCA1rYwpiATEzwJjLxDbFaUG3Zg+sjk+TG LIRXPqbS1Sl4+yW/vM3ui5nz0NvBlOi92SZdj2qC8wuQp49/ErN1gtFdmRXJ72iGxRrm rC0A== X-Gm-Message-State: AOAM53068kEUI6lcBAPqupRNbfsfhPe0PPwPZA2+CEbfY3UFMQUJBC3z xnJj4LHfOtKuhA4pVpntfRriiW387Ux5t8/ePQO1uQ== X-Google-Smtp-Source: ABdhPJzSboXwnnS0/thmw7CuzyUHM03XYqiCBjMHIwhkm1SAQSPGnGM5ifsQTkbKP3ZO2Dj7lMNkZHnZs8mC6HOABM0= X-Received: by 2002:a0d:f9c5:0:b0:2db:7a9a:b01a with SMTP id j188-20020a0df9c5000000b002db7a9ab01amr24767075ywf.458.1646396253728; Fri, 04 Mar 2022 04:17:33 -0800 (PST) MIME-Version: 1.0 References: <20220304093409.25829-1-linmiaohe@huawei.com> <20220304093409.25829-5-linmiaohe@huawei.com> In-Reply-To: <20220304093409.25829-5-linmiaohe@huawei.com> From: Muchun Song Date: Fri, 4 Mar 2022 20:16:46 +0800 Message-ID: Subject: Re: [PATCH 04/16] mm/migration: reduce the rcu lock duration To: Miaohe Lin Cc: Andrew Morton , Mike Kravetz , Yang Shi , Matthew Wilcox , Huang Ying , Zi Yan , Minchan Kim , Alistair Popple , ave.hansen@linux.intel.com, o451686892@gmail.com, Mina Almasry , John Hubbard , Ralph Campbell , Peter Xu , =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , Michal Hocko , riel@redhat.com, Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 59EB1A0010 X-Stat-Signature: 4mrdym7sgqy8tcqfgctfwgm8ccy19j6x Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=zDewUWU4; spf=pass (imf15.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.128.181 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-Rspam-User: X-HE-Tag: 1646396254-184402 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 Fri, Mar 4, 2022 at 5:35 PM Miaohe Lin wrote: > > rcu_read_lock is required by grabbing the task refcount but it's not > needed for ptrace_may_access. So we could release the rcu lock after > task refcount is successfully grabbed to reduce the rcu holding time. > > Signed-off-by: Miaohe Lin Also simple. Reviewed-by: Muchun Song