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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 66B31C7618B for ; Mon, 29 Jul 2019 08:18:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3517720644 for ; Mon, 29 Jul 2019 08:18:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3517720644 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D65AA8E0003; Mon, 29 Jul 2019 04:18:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D152D8E0002; Mon, 29 Jul 2019 04:18:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C04108E0003; Mon, 29 Jul 2019 04:18:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id 8825E8E0002 for ; Mon, 29 Jul 2019 04:18:06 -0400 (EDT) Received: by mail-ed1-f69.google.com with SMTP id b3so37770026edd.22 for ; Mon, 29 Jul 2019 01:18:06 -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=zv1jyHrQhg/anG79DXIg6d42L7l6b6qBUMNYIf//wxg=; b=ZIgtHLUMi1FkKui1tiYW+lFJHrd9PdJenx++vs9ufFolTGI5B6B5SrInyD9evhNxOT bj/OXi2Gc6uIJwHlPtqy8atKFV4CnZ3bbVoyNG58eT4VT+sEQXFQR6hiaSrgWbiyMpsg c1iK9KthF5mey4Fh0SZdVH+qfmMpdz3dKFxovywlL0AyIrhXg72rQUi0X/hlEg4va8qO yV335A5ia5ukWW2L4oaZDbJiiLt4U9Z/7qXvTxcAkyUjzqp4Uf+0q4WdrrB9AbMVdzIt zTO+9taqAbW8NCT1/KBopNeHXHmtno/YkvRSdY3zixmbZ4VRtoZlHCkh82X8I2jE44lq Cupw== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of qais.yousef@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=qais.yousef@arm.com X-Gm-Message-State: APjAAAWOabJtPMygeWzCasZWuEBQuFyNi/nNwSeGhYsxncVilIeFTPI9 ivu9rv26UvI8E/BvafqdK2bGbQnH7vxyN5IOowiO1zrJJPRv/sbkmvtf0A8ST2YGPjbGCU3wqwV +OegaMfNfwD4U7rymxWHI+N7nQ7r7CubJ0K0AbeHhe69mqaI7+LU9Z2IiDZbT9KRJxg== X-Received: by 2002:a17:906:6bd4:: with SMTP id t20mr79755275ejs.294.1564388286104; Mon, 29 Jul 2019 01:18:06 -0700 (PDT) X-Google-Smtp-Source: APXvYqy+PDzwO6O7ec0nxWP6AznZVgCuNGS36odH9RDkrStEvsBMEb78vFpB62wvNUxnQBAH9TqZ X-Received: by 2002:a17:906:6bd4:: with SMTP id t20mr79755238ejs.294.1564388285329; Mon, 29 Jul 2019 01:18:05 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1564388285; cv=none; d=google.com; s=arc-20160816; b=r3AC22Woa18aZAUjkPuQUdXw3//UcWj1zPKA1iK466RFPwfrJOu8Y6LdHNVD2Ogls1 K9hj50yQuuHcCiIdLuFCZS0r3UUAklk+e++jWhWCoXbKslU9yJx0ZfxQOO3irWkz/SVr Yw9kE5ujeHeOXTr4pPSDdjjWqDLpbu+854cDeemIL+3sEL0VrjAIBqfVPPoUf6cIawqd uL674AMuMqNVMFRh0UO4RHaKQYI0b+Xu+OoUPOijc4F2PLH7k14+wVkDEj3SXPO93STn ohw+rruBTeEgWMfOm/5/y19fjLce5gqFeP1OqgFCDMY7oo4sV9aU+myzIziHWpWeUa1T Yd9g== 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=zv1jyHrQhg/anG79DXIg6d42L7l6b6qBUMNYIf//wxg=; b=xACcx3QEAwghnMpOH3XJynE3iJ6/CswSDpZ0y53IraCEtoqNfhfTKGTTuLmUDo/Dx7 nU7YIZcZKpBF81XeYaizLjHruZs+ACLpeOttUEUPG1gn1ia8QBB4e9t9VimXMV4wIOiK iVDeOhh2+nWVgi99zoK7rFuMC05mmbA7fAnomD1C9/4ZAYXgtJPqgG7C9lH50I2+59RH gBZ9bSHBku/KtcEoQ4uJyWaPBmuhbCA82KcYG+P9Mcf5BXo0JMq/U0q8j0zZldMCiCvC zmfyEG8i8CKUUieJiaeif9evrNLUAJ0m43QqELhWFErW7Us43hzOzdRWycNWrzda02hW fbFA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of qais.yousef@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=qais.yousef@arm.com Received: from foss.arm.com (foss.arm.com. [217.140.110.172]) by mx.google.com with ESMTP id l31si16933003edb.143.2019.07.29.01.18.05 for ; Mon, 29 Jul 2019 01:18:05 -0700 (PDT) Received-SPF: pass (google.com: domain of qais.yousef@arm.com designates 217.140.110.172 as permitted sender) client-ip=217.140.110.172; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qais.yousef@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=qais.yousef@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7D12E337; Mon, 29 Jul 2019 01:18:04 -0700 (PDT) Received: from e107158-lin.cambridge.arm.com (unknown [10.1.194.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 78F283F575; Mon, 29 Jul 2019 01:18:03 -0700 (PDT) Date: Mon, 29 Jul 2019 09:18:01 +0100 From: Qais Yousef To: Waiman Long Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Phil Auld Subject: Re: [PATCH v2] sched/core: Don't use dying mm as active_mm of kthreads Message-ID: <20190729081800.qbamrvsf4rjna656@e107158-lin.cambridge.arm.com> References: <20190727171047.31610-1-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190727171047.31610-1-longman@redhat.com> User-Agent: NeoMutt/20171215 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 07/27/19 13:10, Waiman Long wrote: > It was found that a dying mm_struct where the owning task has exited > can stay on as active_mm of kernel threads as long as no other user > tasks run on those CPUs that use it as active_mm. This prolongs the > life time of dying mm holding up memory and other resources like swap > space that cannot be freed. > > Fix that by forcing the kernel threads to use init_mm as the active_mm > if the previous active_mm is dying. > > The determination of a dying mm is based on the absence of an owning > task. The selection of the owning task only happens with the CONFIG_MEMCG > option. Without that, there is no simple way to determine the life span > of a given mm. So it falls back to the old behavior. I don't really know a lot about this code, but does the owner field has to depend on CONFIG_MEMCG? ie: can't the owner be always set? Cheers -- Qais Yousef