From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757363Ab2ILKey (ORCPT ); Wed, 12 Sep 2012 06:34:54 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:44300 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757262Ab2ILKev (ORCPT ); Wed, 12 Sep 2012 06:34:51 -0400 From: Michal Nazarewicz To: Minchan Kim , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim , Kamezawa Hiroyuki , Yasuaki Ishimatsu , Marek Szyprowski , Wen Congyang Subject: Re: [PATCH 2/2] memory-hotplug: don't replace lowmem pages with highmem In-Reply-To: <1347414231-31451-2-git-send-email-minchan@kernel.org> Organization: http://mina86.com/ References: <1347414231-31451-1-git-send-email-minchan@kernel.org> <1347414231-31451-2-git-send-email-minchan@kernel.org> User-Agent: Notmuch/0.14+22~g8bdc16b (http://notmuchmail.org) Emacs/24.2.50.1 (x86_64-unknown-linux-gnu) X-Face: PbkBB1w#)bOqd`iCe"Ds{e+!C7`pkC9a|f)Qo^BMQvy\q5x3?vDQJeN(DS?|-^$uMti[3D*#^_Ts"pU$jBQLq~Ud6iNwAw_r_o_4]|JO?]}P_}Nc&"p#D(ZgUb4uCNPe7~a[DbPG0T~!&c.y$Ur,=N4RT>]dNpd;KFrfMCylc}gc??'U2j,!8%xdD Face: 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 X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 Date: Wed, 12 Sep 2012 12:34:41 +0200 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Wed, Sep 12 2012, Minchan Kim wrote: > [1] reporeted that lowmem pages could be replaced by > highmem pages during migration of CMA and fixed. > > Quote from [1]'s description > " > The filesystem layer expects pages in the block device's mapping to n= ot > be in highmem (the mapping's gfp mask is set in bdget()), but CMA can > currently replace lowmem pages with highmem pages, leading to crashes= in > filesystem code such as the one below: > > Unable to handle kernel NULL pointer dereference at virtual address= 00000400 > pgd =3D c0c98000 > [00000400] *pgd=3D00c91831, *pte=3D00000000, *ppte=3D00000000 > Internal error: Oops: 817 [#1] PREEMPT SMP ARM > CPU: 0 Not tainted (3.5.0-rc5+ #80) > PC is at __memzero+0x24/0x80 > ... > Process fsstress (pid: 323, stack limit =3D 0xc0cbc2f0) > Backtrace: > [] (ext4_getblk+0x0/0x180) from [] (ext4_bread+= 0x1c/0x98) > [] (ext4_bread+0x0/0x98) from [] (ext4_mkdir+0x= 160/0x3bc) > r4:c15337f0 > [] (ext4_mkdir+0x0/0x3bc) from [] (vfs_mkdir+0x= 8c/0x98) > [] (vfs_mkdir+0x0/0x98) from [] (sys_mkdirat+0x= 74/0xac) > r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0 > [] (sys_mkdirat+0x0/0xac) from [] (sys_mkdir+0x= 20/0x24) > r6:beccdcf0 r5:00074000 r4:beccdbbc > [] (sys_mkdir+0x0/0x24) from [] (ret_fast_sysca= ll+0x0/0x30) > " > > Memory-hotplug has same problem with CMA so [1]'s fix could be applied > with memory-hotplug, too. > > Fix it by reusing. > > [1] 6a6dccba2, mm: cma: don't replace lowmem pages with highmem > > Cc: Kamezawa Hiroyuki > Cc: Yasuaki Ishimatsu > Cc: Michal Nazarewicz Looks legit: Acked-by: Michal Nazarewicz I also like how both of the patches cumulatively have negative delta. :] > Cc: Marek Szyprowski > Cc: Wen Congyang > Signed-off-by: Minchan Kim --=20 Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=3D./ `o ..o | Computer Science, Micha=C5=82 =E2=80=9Cmina86=E2=80=9D Nazarewicz = (o o) ooo +------------------ooO--(_)--Ooo-- --=-=-= Content-Type: multipart/signed; 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