From 8ae30b895805a6e2bb725b1d78b12daabd7eadfe Mon Sep 17 00:00:00 2001 From: Milan Broz Date: Fri, 12 Dec 2008 14:50:49 +0100 Subject: [PATCH] loop: Do not call loop_unplug for not configured loop device. In loop_unplug() function is expected that mapping is set and lo->lo_backing_file is not NULL. Unfortunately loop_set_fd() set the request queue unplug function, but loop_clr_fd() doesn't clear that. Loop device allows open of non-configured loop in some situations. If the unplug on request queue is called, loop module oopses because of missing lo_backing_file. Simple reproducer: losetup /dev/loop0 /xxx losetup -d /dev/loop0 dmsetup create x --table "0 1 linear /dev/loop0 0" EIP is at loop_unplug+0x1d/0x3b ... Call Trace: blk_unplug+0x57/0x5e dm_table_unplug_all+0x34/0x77 [dm_mod] destroy_inode+0x27/0x38 generic_delete_inode+0xd5/0xd9 iput+0x4b/0x4e dm_resume+0xca/0xfe [dm_mod] dev_suspend+0x143/0x165 [dm_mod] dm_ctl_ioctl+0x18e/0x1cf [dm_mod] dev_suspend+0x0/0x165 [dm_mod] dm_ctl_ioctl+0x0/0x1cf [dm_mod] vfs_ioctl+0x22/0x69 do_vfs_ioctl+0x39d/0x3c7 trace_hardirqs_on+0xb/0xd remove_vma+0x50/0x56 do_munmap+0x21c/0x237 sys_ioctl+0x2c/0x45 sysenter_do_call+0x12/0x31 Several reports here http://www.kerneloops.org/search.php?search=loop_unplug Fix it by simply clear unplug function together with removing of backing file. Signed-off-by: Milan Broz Signed-off-by: Jens Axboe --- drivers/block/loop.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 66cfff7..edbaac6 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -919,6 +919,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) kthread_stop(lo->lo_thread); + lo->lo_queue->unplug_fn = NULL; lo->lo_backing_file = NULL; loop_release_xfer(lo); -- 2.7.4