The patch titled swapfile: avoid NULL pointer dereference in swapon when s_bdev is NULL has been removed from the -mm tree. Its filename was swapfile-avoid-null-pointer-dereference-in-swapon-when-s_bdev-is-null.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: swapfile: avoid NULL pointer dereference in swapon when s_bdev is NULL From: Suresh Jayaraman <sjayaraman@xxxxxxx> While testing Swap over NFS patchset, I noticed an oops that was triggered during swapon. Investigating further, the NULL pointer deference is due to the SSD device check/optimization in the swapon code that assumes s_bdev could never be NULL. inode->i_sb->s_bdev could be NULL in a few cases. For e.g. one such case is loopback NFS mount, there could be others as well. Fix this by ensuring s_bdev is not NULL before we try to deference s_bdev. Signed-off-by: Suresh Jayaraman <sjayaraman@xxxxxxx> Cc: Jens Axboe <jens.axboe@xxxxxxxxxx> Cc: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/swapfile.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff -puN mm/swapfile.c~swapfile-avoid-null-pointer-dereference-in-swapon-when-s_bdev-is-null mm/swapfile.c --- a/mm/swapfile.c~swapfile-avoid-null-pointer-dereference-in-swapon-when-s_bdev-is-null +++ a/mm/swapfile.c @@ -1974,12 +1974,14 @@ SYSCALL_DEFINE2(swapon, const char __use goto bad_swap; } - if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { - p->flags |= SWP_SOLIDSTATE; - p->cluster_next = 1 + (random32() % p->highest_bit); + if (p->bdev) { + if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { + p->flags |= SWP_SOLIDSTATE; + p->cluster_next = 1 + (random32() % p->highest_bit); + } + if (discard_swap(p) == 0) + p->flags |= SWP_DISCARDABLE; } - if (discard_swap(p) == 0) - p->flags |= SWP_DISCARDABLE; mutex_lock(&swapon_mutex); spin_lock(&swap_lock); _ Patches currently in -mm which might be from sjayaraman@xxxxxxx are linux-next.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