The patch titled
Subject: swapfile: avoid dereferencing bd_disk during swap_entry_free for network storage
has been added to the -mm tree. Its filename is
swapfile-avoid-dereferencing-bd_disk-during-swap_entry_free-for-network-storage.patch
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From: Mel Gorman <mgorman@xxxxxxx>
Subject: swapfile: avoid dereferencing bd_disk during swap_entry_free for network storage
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@xxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Eric B Munson <emunson@xxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Mike Christie <michaelc@xxxxxxxxxxx>
Cc: Neil Brown <neilb@xxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Sebastian Andrzej Siewior <sebastian@xxxxxxxxxxxxx>
Cc: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff -puN mm/swapfile.c~swapfile-avoid-dereferencing-bd_disk-during-swap_entry_free-for-network-storage mm/swapfile.c
--- a/mm/swapfile.c~swapfile-avoid-dereferencing-bd_disk-during-swap_entry_free-for-network-storage
+++ a/mm/swapfile.c
@@ -549,7 +549,6 @@ static unsigned char swap_entry_free(str
/* 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(str
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;
_
Subject: Subject: swapfile: avoid dereferencing bd_disk during swap_entry_free for network storage
Patches currently in -mm which might be from mgorman@xxxxxxx are
origin.patch
linux-next.patch
memcg-prevent-oom-with-too-many-dirty-pages.patch
memcg-prevent-oom-with-too-many-dirty-pages-fix.patch
mm-do-not-use-page_count-without-a-page-pin.patch
mm-clean-up-__count_immobile_pages.patch
mm-hotplug-correctly-setup-fallback-zonelists-when-creating-new-pgdat.patch
mm-hotplug-correctly-add-new-zone-to-all-other-nodes-zone-lists.patch
mm-hotplug-free-zone-pageset-when-a-zone-becomes-empty.patch
mm-hotplug-mark-memory-hotplug-code-in-page_allocc-as-__meminit.patch
mm-factor-out-memory-isolate-functions.patch
mm-bug-fix-free-page-check-in-zone_watermark_ok.patch
memory-hotplug-fix-kswapd-looping-forever-problem.patch
memory-hotplug-fix-kswapd-looping-forever-problem-fix.patch
mm-slb-add-knowledge-of-pfmemalloc-reserve-pages.patch
mm-slub-optimise-the-slub-fast-path-to-avoid-pfmemalloc-checks.patch
mm-introduce-__gfp_memalloc-to-allow-access-to-emergency-reserves.patch
mm-allow-pf_memalloc-from-softirq-context.patch
mm-only-set-page-pfmemalloc-when-alloc_no_watermarks-was-used.patch
mm-ignore-mempolicies-when-using-alloc_no_watermark.patch
net-introduce-sk_gfp_atomic-to-allow-addition-of-gfp-flags-depending-on-the-individual-socket.patch
netvm-allow-the-use-of-__gfp_memalloc-by-specific-sockets.patch
netvm-allow-skb-allocation-to-use-pfmemalloc-reserves.patch
netvm-propagate-page-pfmemalloc-to-skb.patch
netvm-propagate-page-pfmemalloc-from-skb_alloc_page-to-skb.patch
netvm-set-pf_memalloc-as-appropriate-during-skb-processing.patch
mm-micro-optimise-slab-to-avoid-a-function-call.patch
nbd-set-sock_memalloc-for-access-to-pfmemalloc-reserves.patch
mm-throttle-direct-reclaimers-if-pf_memalloc-reserves-are-low-and-swap-is-backed-by-network-storage.patch
mm-account-for-the-number-of-times-direct-reclaimers-get-throttled.patch
netvm-prevent-a-stream-specific-deadlock.patch
selinux-tag-avc-cache-alloc-as-non-critical.patch
mm-methods-for-teaching-filesystems-about-pg_swapcache-pages.patch
mm-add-support-for-a-filesystem-to-activate-swap-files-and-use-direct_io-for-writing-swap-pages.patch
mm-swap-implement-generic-handler-for-swap_activate.patch
mm-add-get_kernel_page-for-pinning-of-kernel-addresses-for-i-o.patch
mm-add-support-for-direct_io-to-highmem-pages.patch
nfs-teach-the-nfs-client-how-to-treat-pg_swapcache-pages.patch
nfs-disable-data-cache-revalidation-for-swapfiles.patch
nfs-enable-swap-on-nfs.patch
nfs-prevent-page-allocator-recursions-with-swap-over-nfs.patch
swapfile-avoid-dereferencing-bd_disk-during-swap_entry_free-for-network-storage.patch
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