From: Mel Gorman <mgorman@suse.de> To: Andrew Morton <akpm@linux-foundation.org> Cc: Linux-MM <linux-mm@kvack.org>, Linux-Netdev <netdev@vger.kernel.org>, Linux-NFS <linux-nfs@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, David Miller <davem@davemloft.net>, Trond Myklebust <Trond.Myklebust@netapp.com>, Neil Brown <neilb@suse.de>, Christoph Hellwig <hch@infradead.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Mike Christie <michaelc@cs.wisc.edu>, Eric B Munson <emunson@mgebm.net>, Sebastian Andrzej Siewior <sebastian@breakpoint.cc>, Mel Gorman <mgorman@suse.de> Subject: [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Date: Fri, 29 Jun 2012 14:33:25 +0100 [thread overview] Message-ID: <1340976805-5799-13-git-send-email-mgorman@suse.de> (raw) In-Reply-To: <1340976805-5799-1-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. With reference to this callback, Christoph Hellwig stated "Please just remove the callback entirely. It has no user outside the staging tree and was added clearly against the rules for that staging tree". This would also be my preference but there was not an obvious way of keeping zram in staging/ happy. Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> --- mm/swapfile.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 1d77b13..f4c802d 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -549,7 +549,6 @@ 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) @@ -560,9 +559,11 @@ static unsigned char swap_entry_free(struct swap_info_struct *p, nr_swap_pages++; p->inuse_pages--; frontswap_invalidate_page(p->type, offset); - 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; -- 1.7.9.2
WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de> To: Andrew Morton <akpm@linux-foundation.org> Cc: Linux-MM <linux-mm@kvack.org>, Linux-Netdev <netdev@vger.kernel.org>, Linux-NFS <linux-nfs@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, David Miller <davem@davemloft.net>, Trond Myklebust <Trond.Myklebust@netapp.com>, Neil Brown <neilb@suse.de>, Christoph Hellwig <hch@infradead.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Mike Christie <michaelc@cs.wisc.edu>, Eric B Munson <emunson@mgebm.net>, Sebastian Andrzej Siewior <sebastian@breakpoint.cc>, Mel Gorman <mgorman@suse.de> Subject: [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Date: Fri, 29 Jun 2012 14:33:25 +0100 [thread overview] Message-ID: <1340976805-5799-13-git-send-email-mgorman@suse.de> (raw) In-Reply-To: <1340976805-5799-1-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. With reference to this callback, Christoph Hellwig stated "Please just remove the callback entirely. It has no user outside the staging tree and was added clearly against the rules for that staging tree". This would also be my preference but there was not an obvious way of keeping zram in staging/ happy. Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> --- mm/swapfile.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 1d77b13..f4c802d 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -549,7 +549,6 @@ 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) @@ -560,9 +559,11 @@ static unsigned char swap_entry_free(struct swap_info_struct *p, nr_swap_pages++; p->inuse_pages--; frontswap_invalidate_page(p->type, offset); - 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; -- 1.7.9.2 -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-06-29 13:34 UTC|newest] Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-06-29 13:33 [PATCH 00/12] Swap-over-NFS without deadlocking V8 Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 01/12] netvm: Prevent a stream-specific deadlock Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 02/12] selinux: tag avc cache alloc as non-critical Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 03/12] mm: Methods for teaching filesystems about PG_swapcache pages Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 04/12] mm: Add support for a filesystem to activate swap files and use direct_IO for writing swap pages Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 05/12] mm: swap: Implement generic handler for swap_activate Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 06/12] mm: Add get_kernel_page[s] for pinning of kernel addresses for I/O Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 07/12] mm: Add support for direct_IO to highmem pages Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 08/12] nfs: teach the NFS client how to treat PG_swapcache pages Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 09/12] nfs: disable data cache revalidation for swapfiles Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 10/12] nfs: enable swap on NFS Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` [PATCH 11/12] nfs: Prevent page allocator recursions with swap over NFS Mel Gorman 2012-06-29 13:33 ` Mel Gorman 2012-06-29 13:33 ` Mel Gorman [this message] 2012-06-29 13:33 ` [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman 2012-07-01 17:22 ` [PATCH 00/12] Swap-over-NFS without deadlocking V8 Eric B Munson 2012-07-02 14:35 ` Mel Gorman 2012-07-02 14:35 ` Mel Gorman 2012-07-03 0:10 ` Eric B Munson 2012-07-03 8:58 ` Mel Gorman 2012-07-03 8:58 ` Mel Gorman -- strict thread matches above, loose matches on Subject: below -- 2012-07-12 6:40 [PATCH 00/12] Swap-over-NFS without deadlocking V9 Mel Gorman 2012-07-12 6:41 ` [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman 2012-07-12 6:41 ` Mel Gorman 2012-06-22 14:30 [PATCH 00/12] Swap-over-NFS without deadlocking V7 Mel Gorman 2012-06-22 14:31 ` [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman 2012-06-22 14:31 ` Mel Gorman 2012-06-20 9:37 [PATCH 00/12] Swap-over-NFS without deadlocking V6 Mel Gorman 2012-06-20 9:38 ` [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman 2012-06-20 9:38 ` Mel Gorman 2012-06-20 17:47 ` Rik van Riel 2012-06-20 17:47 ` Rik van Riel 2012-05-17 14:51 [PATCH 00/12] Swap-over-NFS without deadlocking V5 Mel Gorman 2012-05-17 14:51 ` [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman 2012-05-17 14:51 ` Mel Gorman 2012-05-17 14:51 ` Mel Gorman 2012-05-10 13:54 [PATCH 00/12] Swap-over-NFS without deadlocking V4 Mel Gorman 2012-05-10 13:54 ` [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman 2012-05-10 13:54 ` Mel Gorman
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