From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751636AbcFVWVY (ORCPT ); Wed, 22 Jun 2016 18:21:24 -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 S1751026AbcFVWVX (ORCPT ); Wed, 22 Jun 2016 18:21:23 -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: <576B0F57.3030700@nod.at> Date: Thu, 23 Jun 2016 00:21:11 +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 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? > > [2/3] is of course OK - please add it to the UBIFS tree. Pushed 2/3 and 3/3 into UBIFS next tree. Thanks, //richard