block: kill loop_mutex
Following steps lead to deadlock in kernel: dd if=/dev/zero of=img bs=512 count=1000 losetup -f img mkfs.ext2 /dev/loop0 mount -t ext2 -o loop /dev/loop0 mnt umount mnt/ Stacktrace: [<c102ec04>] irq_exit+0x36/0x59 [<c101502c>] smp_apic_timer_interrupt+0x6b/0x75 [<c127f639>] apic_timer_interrupt+0x31/0x38 [<c101df88>] mutex_spin_on_owner+0x54/0x5b [<fe2250e9>] lo_release+0x12/0x67 [loop] [<c10c4eae>] __blkdev_put+0x7c/0x10c [<c10a4da5>] fput+0xd5/0x1aa [<fe2250cf>] loop_clr_fd+0x1a9/0x1b1 [loop] [<fe225110>] lo_release+0x39/0x67 [loop] [<c10c4eae>] __blkdev_put+0x7c/0x10c [<c10a59d9>] deactivate_locked_super+0x17/0x36 [<c10b6f37>] sys_umount+0x27e/0x2a5 [<c10b6f69>] sys_oldumount+0xb/0xe [<c1002897>] sysenter_do_call+0x12/0x26 [<ffffffff>] 0xffffffff Regression since 2a48fc0a, which introduced the private loop_mutex as part of the BKL removal process. As per [1], the mutex can be safely removed. [1] http://www.gossamer-threads.com/lists/linux/kernel/1341930 Addresses: https://bugzilla.novell.com/show_bug.cgi?id=669394 Addresses: https://bugzilla.kernel.org/show_bug.cgi?id=29172Signed-off-by: NPetr Uzel <petr.uzel@suse.cz> Cc: stable@kernel.org Reviewed-by: NNikanth Karthikesan <knikanth@suse.de> Acked-by: NArnd Bergmann <arnd@arndb.de> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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