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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html