From ee71a968672a9951aee6014c55511007596425bc Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Wed, 19 Jan 2011 08:25:02 -0700 Subject: [PATCH] loop: queue_lock NULL pointer derefence in blk_throtl_exit 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: [] do_raw_spin_lock+0x14/0x122 Process modprobe (pid: 6189, threadinfo ffff88009a898000, task ffff880154a88000) Call Trace: [] _raw_spin_lock_irq+0x4a/0x51 [] ? blk_throtl_exit+0x3b/0xa0 [] ? cancel_delayed_work_sync+0xd/0xf [] blk_throtl_exit+0x3b/0xa0 [] blk_release_queue+0x21/0x65 [] kobject_release+0x51/0x66 [] ? kobject_release+0x0/0x66 [] kref_put+0x43/0x4d [] kobject_put+0x47/0x4b [] blk_cleanup_queue+0x56/0x5b [] loop_exit+0x68/0x844 [loop] [] sys_delete_module+0x1e8/0x25b [] ? trace_hardirqs_on_thunk+0x3a/0x3f [] system_call_fastpath+0x16/0x1b because of an attempt to acquire NULL queue_lock. I added the same lines as in blk_queue_make_request - index 44e18c0..49e6a54 100644`fall back to embedded per-queue lock'. Signed-off-by: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Jens Axboe --- drivers/block/loop.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 44e18c073c44..49e6a545eb63 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1641,6 +1641,9 @@ out: static void loop_free(struct loop_device *lo) { + if (!lo->lo_queue->queue_lock) + lo->lo_queue->queue_lock = &lo->lo_queue->__queue_lock; + blk_cleanup_queue(lo->lo_queue); put_disk(lo->lo_disk); list_del(&lo->lo_list); -- 2.20.1