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 2BD3AC433EF for ; Thu, 12 May 2022 20:49:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A08F56B0073; Thu, 12 May 2022 16:49:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9B8586B0075; Thu, 12 May 2022 16:49:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 880BF6B0078; Thu, 12 May 2022 16:49:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 76FAF6B0073 for ; Thu, 12 May 2022 16:49:48 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id 46503120913 for ; Thu, 12 May 2022 20:49:48 +0000 (UTC) X-FDA: 79458282456.28.D9B848D Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf27.hostedemail.com (Postfix) with ESMTP id 640794000F for ; Thu, 12 May 2022 20:49:45 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F157361E72; Thu, 12 May 2022 20:49:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DAE5C385B8; Thu, 12 May 2022 20:49:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1652388586; bh=91VwTcfIVQV9Sz36/J5iHoSXXfz2kqY+YsPiS9hgpKw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kWHMC6thcR1FBN59YemuXc54h/x9NO4z9+BWWzBZNTMnXLhaooqT+XMZQsOXdkBWz teoLtuDKR3/Cs+bZDFjyv7kWH0nYCtOpoO/rlZ6UM4nTnSGTn85Smh2LhB8sixw+ZH Xt2TZu8t4U23f4TpogUiMt+bh4J6jXbiaYDs7TxI= Date: Thu, 12 May 2022 13:49:45 -0700 From: Andrew Morton To: Rei Yamamoto Cc: linmiaohe@huawei.com, aquini@redhat.com, ddutile@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mgorman@techsingularity.net, vvghjk1234@gmail.com Subject: Re: [PATCH] mm, compaction: fast_find_migrateblock() should return pfn in the target zone Message-Id: <20220512134945.fe74df5e322b98ae4046ce15@linux-foundation.org> In-Reply-To: <20220512042733.17976-1-yamamoto.rei@jp.fujitsu.com> References: <4cf33f9c-89bc-f845-10d7-2aa62a20f5e5@huawei.com> <20220512042733.17976-1-yamamoto.rei@jp.fujitsu.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=kWHMC6th; dmarc=none; spf=pass (imf27.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 640794000F X-Rspam-User: X-Stat-Signature: iseoqc4yqojmrgrmw364kdii4fkgkjpg X-HE-Tag: 1652388585-227916 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, 12 May 2022 13:27:33 +0900 Rei Yamamoto wrote: > >> Thank you for your review. > >> The runtime effect is that compaction become unintended behavior. > >> For example, pages not in the target zone are added to cc->migratepages list in isolate_migratepages_block(). > >> As a result, pages migrate between nodes unintentionally. > > > > Many thanks for clarifying. :) Is this worth a Fixes tag or even CC stable? > > > > Thanks! > > Thank you for your reply. > > If add a Fixes tag, I think the following commit: > Fixes: 70b4459 ("mm, compaction: use free lists to quickly locate a migration source") > > Andrew, how do you think about this? Thanks, I added that and also a paragraph describing the effect of the bug: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-compaction-fast_find_migrateblock-should-return-pfn-in-the-target-zone.patch I assume this problem isn't sufficiently serious to require a -stable backport of the fix?