From: Mel Gorman <mgorman@suse.de>
To: Linux-MM <linux-mm@kvack.org>
Cc: Linux-Netdev <netdev@vger.kernel.org>,
Linux-NFS <linux-nfs@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Neil Brown <neilb@suse.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Mel Gorman <mgorman@suse.de>
Subject: [PATCH 10/10] Avoid dereferencing bd_disk during swap_entry_free for network storage
Date: Fri, 9 Sep 2011 12:00:54 +0100 [thread overview]
Message-ID: <1315566054-17209-11-git-send-email-mgorman@suse.de> (raw)
In-Reply-To: <1315566054-17209-1-git-send-email-mgorman@suse.de>
Commit [b3a27d: swap: Add swap slot free callback to
block_device_operations] dereferences p->bdev->bd_disk but this is a
NULL dereference if using swap-over-NFS. This patch checks SWP_BLKDEV
on the swap_info_struct before dereferencing.
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/swapfile.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 806b994..8b85a88 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -547,7 +547,6 @@ static unsigned char swap_entry_free(struct swap_info_struct *p,
/* free if no reference */
if (!usage) {
- struct gendisk *disk = p->bdev->bd_disk;
if (offset < p->lowest_bit)
p->lowest_bit = offset;
if (offset > p->highest_bit)
@@ -557,9 +556,11 @@ static unsigned char swap_entry_free(struct swap_info_struct *p,
swap_list.next = p->type;
nr_swap_pages++;
p->inuse_pages--;
- if ((p->flags & SWP_BLKDEV) &&
- disk->fops->swap_slot_free_notify)
- disk->fops->swap_slot_free_notify(p->bdev, offset);
+ if (p->flags & SWP_BLKDEV) {
+ struct gendisk *disk = p->bdev->bd_disk;
+ if (disk->fops->swap_slot_free_notify)
+ disk->fops->swap_slot_free_notify(p->bdev, offset);
+ }
}
return usage;
--
1.7.3.4
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next prev parent reply other threads:[~2011-09-09 11:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-09 11:00 [RFC PATCH 00/10] Swap-over-NFS without deadlocking v1 Mel Gorman
2011-09-09 11:00 ` [PATCH 01/10] netvm: Prevent a stream-specific deadlock Mel Gorman
2011-09-09 11:00 ` [PATCH 02/10] selinux: tag avc cache alloc as non-critical Mel Gorman
2011-09-09 11:00 ` [PATCH 03/10] mm: Add support for a filesystem to control swap files Mel Gorman
2011-09-09 13:00 ` Christoph Hellwig
2011-09-09 13:15 ` Mel Gorman
2011-09-09 13:36 ` Christoph Hellwig
2011-09-12 9:04 ` Peter Zijlstra
2011-09-12 9:34 ` Mel Gorman
2011-09-12 9:56 ` Peter Zijlstra
2011-09-12 11:56 ` Mel Gorman
2011-09-12 12:06 ` Peter Zijlstra
2011-09-09 11:00 ` [PATCH 04/10] mm: swap: Implement generic handlers for swap-related address ops Mel Gorman
2011-09-09 11:00 ` [PATCH 05/10] mm: Methods for teaching filesystems about PG_swapcache pages Mel Gorman
2011-09-09 11:00 ` [PATCH 06/10] nfs: teach the NFS client how to treat " Mel Gorman
2011-09-09 11:00 ` [PATCH 07/10] nfs: disable data cache revalidation for swapfiles Mel Gorman
2011-09-09 11:00 ` [PATCH 08/10] nfs: enable swap on NFS Mel Gorman
2011-09-09 11:00 ` [PATCH 09/10] nfs: Prevent page allocator recursions with swap over NFS Mel Gorman
2011-09-09 11:00 ` Mel Gorman [this message]
2011-09-09 13:02 ` [PATCH 10/10] Avoid dereferencing bd_disk during swap_entry_free for network storage Christoph Hellwig
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