The patch titled loop: queue_lock NULL pointer derefence in blk_throtl_exit has been added to the -mm tree. Its filename is loop-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v3.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 *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: loop: queue_lock NULL pointer derefence in blk_throtl_exit From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Performing $ sudo mount -o loop -o umask=0 /dev/sdb1 /mnt/ mount: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so $ sudo modprobe -r loop results in oops: BUG: unable to handle kernel NULL pointer dereference at 0000000000000004 IP: [<ffffffff812479d4>] do_raw_spin_lock+0x14/0x122 Process modprobe (pid: 6189, threadinfo ffff88009a898000, task ffff880154a88000) Call Trace: [<ffffffff81486788>] _raw_spin_lock_irq+0x4a/0x51 [<ffffffff8123404b>] ? blk_throtl_exit+0x3b/0xa0 [<ffffffff8105b120>] ? cancel_delayed_work_sync+0xd/0xf [<ffffffff8123404b>] blk_throtl_exit+0x3b/0xa0 [<ffffffff81229bc8>] blk_release_queue+0x21/0x65 [<ffffffff8123bb06>] kobject_release+0x51/0x66 [<ffffffff8123bab5>] ? kobject_release+0x0/0x66 [<ffffffff8123ce1e>] kref_put+0x43/0x4d [<ffffffff8123ba27>] kobject_put+0x47/0x4b [<ffffffff8122717c>] blk_cleanup_queue+0x56/0x5b [<ffffffffa01c3824>] loop_exit+0x68/0x844 [loop] [<ffffffff8107cccc>] sys_delete_module+0x1e8/0x25b [<ffffffff814864c9>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff81002112>] system_call_fastpath+0x16/0x1b because of an attempt to acquire NULL queue_lock. Added the same lines as in blk_queue_make_request - `fall back to embedded per-queue lock' - when call blk_release_queue on allocated but not initialized queue. Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Cc: Jens Axboe <jaxboe@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- block/blk-sysfs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff -puN block/blk-sysfs.c~loop-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v3 block/blk-sysfs.c --- a/block/blk-sysfs.c~loop-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v3 +++ a/block/blk-sysfs.c @@ -471,6 +471,12 @@ static void blk_release_queue(struct kob blk_sync_queue(q); + /* It's possible that blk_release_queue will be called on allocated + * but never initilalized queue. Fall back to our embedded per-queue + * locks in this case. */ + if (!q->queue_lock) + q->queue_lock = &q->__queue_lock; + blk_throtl_exit(q); if (rl->rq_pool) _ Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are loop-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v3.patch loop-queue_lock-null-pointer-derefence-in-blk_throtl_exit.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