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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 02F62C32771 for ; Sat, 18 Jan 2020 22:54:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 96620246AD for ; Sat, 18 Jan 2020 22:54:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bx8VFTpK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 96620246AD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3071A6B0539; Sat, 18 Jan 2020 17:54:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2DD2F6B053B; Sat, 18 Jan 2020 17:54:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1F3656B053C; Sat, 18 Jan 2020 17:54:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0119.hostedemail.com [216.40.44.119]) by kanga.kvack.org (Postfix) with ESMTP id 0480B6B0539 for ; Sat, 18 Jan 2020 17:54:23 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 8D700180AD815 for ; Sat, 18 Jan 2020 22:54:23 +0000 (UTC) X-FDA: 76392260406.26.word43_931d03cdb849 X-HE-Tag: word43_931d03cdb849 X-Filterd-Recvd-Size: 2900 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Sat, 18 Jan 2020 22:54:23 +0000 (UTC) Received: from X1 (nat-ab2241.sltdut.senawave.net [162.218.216.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BBAF1246A5; Sat, 18 Jan 2020 22:54:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579388062; bh=Sev9wYvUYEKc/zi96JR7EJPQmQ+w++cAUQuho0Lvcrw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=bx8VFTpKrukNtyrKYNpWQTv9MPPdUb67f7YOlBo4dKRK+/i/MOj7Eaf0YavBqSzEe /mdWpMo8vERRzmRc3gO8wNVjeuTCRnI5FxQ2nWx6Sot5YFhcS6n69JBLu0rE7IKoF0 p+s5lIVAktqhjyYPmz4/WQHgBENTGQrwmRzX093g= Date: Sat, 18 Jan 2020 14:54:21 -0800 From: Andrew Morton To: Wei Yang Cc: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, ktkhai@virtuozzo.com, kirill.shutemov@linux.intel.com, yang.shi@linux.alibaba.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, alexander.duyck@gmail.com, rientjes@google.com, stable@vger.kernel.org Subject: Re: [Patch v4] mm: thp: remove the defer list related code since this will not happen Message-Id: <20200118145421.0ab96d5d9bea21a3339d52fe@linux-foundation.org> In-Reply-To: <20200117233836.3434-1-richardw.yang@linux.intel.com> References: <20200117233836.3434-1-richardw.yang@linux.intel.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 Sat, 18 Jan 2020 07:38:36 +0800 Wei Yang wrote: > If compound is true, this means it is a PMD mapped THP. Which implies > the page is not linked to any defer list. So the first code chunk will > not be executed. > > Also with this reason, it would not be proper to add this page to a > defer list. So the second code chunk is not correct. > > Based on this, we should remove the defer list related code. > > Fixes: 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware") > > Signed-off-by: Wei Yang > Suggested-by: Kirill A. Shutemov > Cc: [5.4+] This patch is identical to "mm: thp: grab the lock before manipulating defer list", which is rather confusing. Please let people know when this sort of thing is done. The earlier changelog mentioned a possible race condition. This changelog does not. In fact this changelog fails to provide any description of any userspace-visible runtime effects of the bug. Please send along such a description for inclusion, as always.