From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755130AbcFQHlw (ORCPT ); Fri, 17 Jun 2016 03:41:52 -0400 Received: from b.ns.miles-group.at ([95.130.255.144]:44724 "EHLO radon.swed.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753830AbcFQHlv (ORCPT ); Fri, 17 Jun 2016 03:41:51 -0400 Subject: Re: [PATCH 1/3] mm: Don't blindly assign fallback_migrate_page() To: Andrew Morton References: <1466112375-1717-1-git-send-email-richard@nod.at> <1466112375-1717-2-git-send-email-richard@nod.at> <20160616161121.35ee5183b9ef9f7b7dcbc815@linux-foundation.org> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, hannes@cmpxchg.org, mgorman@techsingularity.net, n-horiguchi@ah.jp.nec.com, mhocko@suse.com, kirill.shutemov@linux.intel.com, hughd@google.com, vbabka@suse.cz, adrian.hunter@intel.com, dedekind1@gmail.com, hch@infradead.org, linux-fsdevel@vger.kernel.org, boris.brezillon@free-electrons.com, maxime.ripard@free-electrons.com, david@sigma-star.at, david@fromorbit.com, alex@nextthing.co, sasha.levin@oracle.com, iamjoonsoo.kim@lge.com, rvaswani@codeaurora.org, tony.luck@intel.com, shailendra.capricorn@gmail.com From: Richard Weinberger Message-ID: <5763A9B2.8060303@nod.at> Date: Fri, 17 Jun 2016 09:41:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: <20160616161121.35ee5183b9ef9f7b7dcbc815@linux-foundation.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew, Am 17.06.2016 um 01:11 schrieb Andrew Morton: > On Thu, 16 Jun 2016 23:26:13 +0200 Richard Weinberger wrote: > >> While block oriented filesystems use buffer_migrate_page() >> as page migration function other filesystems which don't >> implement ->migratepage() will automatically get fallback_migrate_page() >> assigned. fallback_migrate_page() is not as generic as is should >> be. Page migration is filesystem specific and a one-fits-all function >> is hard to achieve. UBIFS leaned this lection the hard way. >> It uses various page flags and fallback_migrate_page() does not >> handle these flags as UBIFS expected. >> >> To make sure that no further filesystem will get confused by >> fallback_migrate_page() disable the automatic assignment and >> allow filesystems to use this function explicitly if it is >> really suitable. > > hm, is there really much point in doing this? I assume it doesn't > actually affect any current filesystems? Well, we simply don't know which filesystems are affected by similar issues. JFFS2 is maybe also affected since it is not block based. For UBIFS it also worked many years. > [2/3] is of course OK - please add it to the UBIFS tree. Can I add your Acked-by? Thanks, //richard From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH 1/3] mm: Don't blindly assign fallback_migrate_page() To: Andrew Morton References: <1466112375-1717-1-git-send-email-richard@nod.at> <1466112375-1717-2-git-send-email-richard@nod.at> <20160616161121.35ee5183b9ef9f7b7dcbc815@linux-foundation.org> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, hannes@cmpxchg.org, mgorman@techsingularity.net, n-horiguchi@ah.jp.nec.com, mhocko@suse.com, kirill.shutemov@linux.intel.com, hughd@google.com, vbabka@suse.cz, adrian.hunter@intel.com, dedekind1@gmail.com, hch@infradead.org, linux-fsdevel@vger.kernel.org, boris.brezillon@free-electrons.com, maxime.ripard@free-electrons.com, david@sigma-star.at, david@fromorbit.com, alex@nextthing.co, sasha.levin@oracle.com, iamjoonsoo.kim@lge.com, rvaswani@codeaurora.org, tony.luck@intel.com, shailendra.capricorn@gmail.com From: Richard Weinberger Message-ID: <5763A9B2.8060303@nod.at> Date: Fri, 17 Jun 2016 09:41:38 +0200 MIME-Version: 1.0 In-Reply-To: <20160616161121.35ee5183b9ef9f7b7dcbc815@linux-foundation.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: Andrew, Am 17.06.2016 um 01:11 schrieb Andrew Morton: > On Thu, 16 Jun 2016 23:26:13 +0200 Richard Weinberger wrote: > >> While block oriented filesystems use buffer_migrate_page() >> as page migration function other filesystems which don't >> implement ->migratepage() will automatically get fallback_migrate_page() >> assigned. fallback_migrate_page() is not as generic as is should >> be. Page migration is filesystem specific and a one-fits-all function >> is hard to achieve. UBIFS leaned this lection the hard way. >> It uses various page flags and fallback_migrate_page() does not >> handle these flags as UBIFS expected. >> >> To make sure that no further filesystem will get confused by >> fallback_migrate_page() disable the automatic assignment and >> allow filesystems to use this function explicitly if it is >> really suitable. > > hm, is there really much point in doing this? I assume it doesn't > actually affect any current filesystems? Well, we simply don't know which filesystems are affected by similar issues. JFFS2 is maybe also affected since it is not block based. For UBIFS it also worked many years. > [2/3] is of course OK - please add it to the UBIFS tree. Can I add your Acked-by? Thanks, //richard -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . 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