Hi guys, I hit following warning with 3.9-rc5, during unmount (the device was mounted via loop device, in case it matters). Jongman. [ 3600.583547] INFO: task umount:29671 blocked for more than 120 seconds. [ 3600.583552] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 3600.583555] umount D 0000000000000001 0 29671 29632 0x00000000 [ 3600.583561] ffff88011ecb5c98 0000000000000086 ffff880130ccade0 0000000000013e40 [ 3600.583566] ffff88011ecb5fd8 ffff88011ecb4010 0000000000013e40 0000000000013e40 [ 3600.583571] ffff88011ecb5fd8 0000000000013e40 ffff880132518000 ffff880130ccade0 [ 3600.583575] Call Trace: [ 3600.583583] [] schedule+0x29/0x70 [ 3600.583589] [] schedule_preempt_disabled+0xe/0x10 [ 3600.583593] [] __mutex_lock_slowpath+0xdf/0x160 [ 3600.583598] [] ? release_sysfs_dirent+0x7e/0x100 [ 3600.583603] [] mutex_lock+0x2b/0x50 [ 3600.583607] [] loop_clr_fd+0x24a/0x2e0 [ 3600.583612] [] ? _raw_spin_lock+0xe/0x20 [ 3600.583617] [] lo_release+0x78/0x90 [ 3600.583622] [] __blkdev_put+0x194/0x1d0 [ 3600.583628] [] blkdev_put+0x5d/0x160 [ 3600.583633] [] kill_block_super+0x4d/0x80 [ 3600.583638] [] deactivate_locked_super+0x45/0x70 [ 3600.583643] [] deactivate_super+0x4a/0x70 [ 3600.583648] [] mntput_no_expire+0xf8/0x150 [ 3600.583653] [] sys_umount+0xcd/0x3e0 [ 3600.583659] [] system_call_fastpath+0x16/0x1b [ 3600.583663] INFO: task blkid:29673 blocked for more than 120 seconds. [ 3600.583665] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 3600.583667] blkid D ffffffff81807f20 0 29673 1 0x00000000 [ 3600.583672] ffff88011338fa88 0000000000000082 ffff880130ccc4d0 0000000000013e40 [ 3600.583677] ffff88011338ffd8 ffff88011338e010 0000000000013e40 0000000000013e40 [ 3600.583681] ffff88011338ffd8 0000000000013e40 ffff880132b416f0 ffff880130ccc4d0 [ 3600.583686] Call Trace: [ 3600.583691] [] schedule+0x29/0x70 [ 3600.583695] [] schedule_preempt_disabled+0xe/0x10 [ 3600.583700] [] __mutex_lock_slowpath+0xdf/0x160 [ 3600.583704] [] mutex_lock+0x2b/0x50 [ 3600.583709] [] __blkdev_get+0x73/0x480 [ 3600.583714] [] ? blkdev_get+0x360/0x360 [ 3600.583719] [] blkdev_get+0x51/0x360 [ 3600.583724] [] ? _raw_spin_lock+0xe/0x20 [ 3600.583729] [] ? blkdev_get+0x360/0x360 [ 3600.583734] [] blkdev_open+0x62/0x80 [ 3600.583739] [] do_dentry_open+0x23e/0x2c0 [ 3600.583743] [] finish_open+0x35/0x50 [ 3600.583748] [] do_last+0x696/0xe50 [ 3600.583752] [] ? kmem_cache_alloc_trace+0xc4/0x120 [ 3600.583757] [] path_openat+0xb8/0x490 [ 3600.583762] [] do_filp_open+0x49/0xa0 [ 3600.583767] [] ? _raw_spin_lock+0xe/0x20 [ 3600.583772] [] ? __alloc_fd+0xb5/0x160 [ 3600.583777] [] do_sys_open+0x108/0x1f0 [ 3600.583781] [] sys_open+0x21/0x30 [ 3600.583786] [] system_call_fastpath+0x16/0x1b{.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I