From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx157.postini.com [74.125.245.157]) by kanga.kvack.org (Postfix) with SMTP id B3ACA6B00B9 for ; Wed, 12 Sep 2012 06:34:51 -0400 (EDT) Received: by wibhm6 with SMTP id hm6so3982785wib.8 for ; Wed, 12 Sep 2012 03:34:50 -0700 (PDT) From: Michal Nazarewicz 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> References: <1347414231-31451-1-git-send-email-minchan@kernel.org> <1347414231-31451-2-git-send-email-minchan@kernel.org> Date: Wed, 12 Sep 2012 12:34:41 +0200 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kamezawa Hiroyuki , Yasuaki Ishimatsu , Marek Szyprowski , Wen Congyang --=-=-= 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; boundary="==-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" --==-=-= Content-Type: text/plain --==-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iQIcBAEBAgAGBQJQUGVBAAoJECBgQBJQdR/0uysP+wUFnJi/YidjhWYibmgSVs2L fwd6FDd/gIyZFise15T+q4a0bEthtCMGCDOeMJEKU6cEbeHFKFNCXUUjLuJom8kj iarPCPvAhZvD+Zj31A/XPu/6OkdfkAJoK3qcjeHQrLvG+U9bCUPBCXG/Dn0HRrso PL5cIUSoitCJpHLEnF2s3TKheUj4uOjSTXKN1KUsd1qLKzm6zXZrxjI7TkD/Kmjz ttqjYjgDqdSsSto2MoBzbTyY41NOGegNtIJpK7VSbvxUn/3OZIOkuPCMY93oiNXG YNsmQW4IrA36Kxbub9bt4GJYwxgwLp8gomQj8r+bRx4NLJOJHS1IFkSDAthjgbJH lu7qZLSIBT4ToW7uC77x+lt6//DZUdW3mGaKFeVKlP4f6INqWzIZMgKHK9roEn4d 2qqB+PocaOwie+jpvCnilFjmIhgEOyYBrC+aBpmezoeT5eXQU2CCNG2jDnnJzT7d YCefC4uT3iKnjgoVl323+paPkSD7ZSJHRM0/KJUFsQyGfbAgJSaqFQrdPIkfDP1u l7QuqvCUFhHMJu9A0OrlYgLCfvZzNJ2oOpI16WinBy8lyZYjHOUF34jaXRvoLFgp pokO0mHyLGB8J6invXOfvoa7zOzh1IB1OGXBZyxaYrKMNoEgEJ95x50KS3zCVvVH A9CbI7SWWFz3Og35jt9x =Ai6o -----END PGP SIGNATURE----- --==-=-=-- --=-=-=-- -- 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/ . Don't email: email@kvack.org