From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx156.postini.com [74.125.245.156]) by kanga.kvack.org (Postfix) with SMTP id 110A36B0123 for ; Wed, 12 Sep 2012 21:58:21 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 1561D3EE0B5 for ; Thu, 13 Sep 2012 10:58:19 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id EF5CE45DE5A for ; Thu, 13 Sep 2012 10:58:18 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id CB9BD45DE50 for ; Thu, 13 Sep 2012 10:58:18 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id B85761DB803F for ; Thu, 13 Sep 2012 10:58:18 +0900 (JST) Received: from g01jpexchkw10.g01.fujitsu.local (g01jpexchkw10.g01.fujitsu.local [10.0.194.49]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 6A2EA1DB803C for ; Thu, 13 Sep 2012 10:58:18 +0900 (JST) Message-ID: <50513DA8.1040909@jp.fujitsu.com> Date: Thu, 13 Sep 2012 10:58:00 +0900 From: Yasuaki Ishimatsu MIME-Version: 1.0 Subject: Re: [PATCH 2/2] memory-hotplug: don't replace lowmem pages with highmem References: <1347414231-31451-1-git-send-email-minchan@kernel.org> <1347414231-31451-2-git-send-email-minchan@kernel.org> In-Reply-To: <1347414231-31451-2-git-send-email-minchan@kernel.org> Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kamezawa Hiroyuki , Michal Nazarewicz , Marek Szyprowski , Wen Congyang 2012/09/12 10:43, 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 not > 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 = c0c98000 > [00000400] *pgd=00c91831, *pte=00000000, *ppte=00000000 > 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 = 0xc0cbc2f0) > Backtrace: > [] (ext4_getblk+0x0/0x180) from [] (ext4_bread+0x1c/0x98) > [] (ext4_bread+0x0/0x98) from [] (ext4_mkdir+0x160/0x3bc) > r4:c15337f0 > [] (ext4_mkdir+0x0/0x3bc) from [] (vfs_mkdir+0x8c/0x98) > [] (vfs_mkdir+0x0/0x98) from [] (sys_mkdirat+0x74/0xac) > r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0 > [] (sys_mkdirat+0x0/0xac) from [] (sys_mkdir+0x20/0x24) > r6:beccdcf0 r5:00074000 r4:beccdbbc > [] (sys_mkdir+0x0/0x24) from [] (ret_fast_syscall+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 Reviewed-by: Yasuaki Ishimatsu Thanks, Yasuaki Ishimatsu > Cc: Michal Nazarewicz > Cc: Marek Szyprowski > Cc: Wen Congyang > Signed-off-by: Minchan Kim > --- > mm/memory_hotplug.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 4491a6b..fb71e5c 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -752,13 +752,6 @@ static unsigned long scan_lru_pages(unsigned long start, unsigned long end) > return 0; > } > > -static struct page * > -hotremove_migrate_alloc(struct page *page, unsigned long private, int **x) > -{ > - /* This should be improooooved!! */ > - return alloc_page(GFP_HIGHUSER_MOVABLE); > -} > - > #define NR_OFFLINE_AT_ONCE_PAGES (256) > static int > do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > @@ -809,8 +802,12 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > putback_lru_pages(&source); > goto out; > } > - /* this function returns # of failed pages */ > - ret = migrate_pages(&source, hotremove_migrate_alloc, 0, > + > + /* > + * alloc_migrate_target should be improooooved!! > + * migrate_pages returns # of failed pages. > + */ > + ret = migrate_pages(&source, alloc_migrate_target, 0, > true, MIGRATE_SYNC); > if (ret) > putback_lru_pages(&source); > -- 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