From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx185.postini.com [74.125.245.185]) by kanga.kvack.org (Postfix) with SMTP id 2B14C6B005A for ; Mon, 28 May 2012 15:13:30 -0400 (EDT) Date: Mon, 28 May 2012 21:13:22 +0200 From: Michal Hocko Subject: Re: [PATCH] mm/hugetlb: Use compound page head in migrate_huge_page Message-ID: <20120528191322.GA10071@tiehlicka.suse.cz> References: <1338218490-30978-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1338218490-30978-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Aneesh Kumar K.V" Cc: linux-mm@kvack.org, kamezawa.hiroyu@jp.fujitsu.com, akpm@linux-foundation.org, rientjes@google.com, linux-kernel@vger.kernel.org On Mon 28-05-12 20:51:30, Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" > > The change was introduced by "hugetlb: simplify migrate_huge_page() " > > We should use compound page head instead of tail pages in > migrate_huge_page(). > > Signed-off-by: Aneesh Kumar K.V > --- > mm/memory-failure.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > This is an important bug fix. If we want we can fold it with the not > yet merged upstream patch mentioned above in linux-next. The stack > trace for the crash is > > [ 75.337421] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 > [ 75.338386] IP: [] __mutex_lock_common+0xa1/0x350 > [ 75.338386] PGD 1d700067 PUD 1d7dd067 PMD 0 > [ 75.338386] Oops: 0002 [#1] SMP > [ 75.338386] CPU 1 > [ 75.338386] Modules linked in: > ... > ... > > [ 75.338386] Call Trace: > [ 75.338386] [] ? try_to_unmap_file+0x38/0x51c > [ 75.338386] [] ? try_to_unmap_file+0x38/0x51c > [ 75.338386] [] ? vsnprintf+0x83/0x421 > [ 75.338386] [] mutex_lock_nested+0x2a/0x31 > [ 75.338386] [] ? alloc_huge_page_node+0x1d/0x55 > [ 75.338386] [] try_to_unmap_file+0x38/0x51c > [ 75.338386] [] ? alloc_huge_page_node+0x1d/0x55 > [ 75.338386] [] ? arch_local_irq_save+0x9/0xc > [ 75.338386] [] ? _raw_spin_unlock+0x23/0x27 > [ 75.338386] [] try_to_unmap+0x25/0x3c > [ 75.338386] [] ? console_unlock+0x210/0x238 > [ 75.338386] [] migrate_huge_page+0x8d/0x178 This should be part of the changelog. > > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 4a45098..53a1495 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1428,8 +1428,8 @@ static int soft_offline_huge_page(struct page *page, int flags) > } > > /* Keep page count to indicate a given hugepage is isolated. */ > - ret = migrate_huge_page(page, new_page, MPOL_MF_MOVE_ALL, 0, true); > - put_page(page); > + ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, 0, true); > + put_page(hpage); > if (ret) { > pr_info("soft offline: %#lx: migration failed %d, type %lx\n", > pfn, ret, page->flags); I guess you want hpage->flags here. -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org