Comment 4 for bug 1424342

[ 3240.018757] INFO: task umount:6807 blocked for more than 120 seconds.
[ 3240.018779] Not tainted 4.4.0-47-generic #68-Ubuntu
[ 3240.018798] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3240.018823] umount D ffff880213c079e8 0 6807 6770 0x00000004
[ 3240.018825] ffff880213c079e8 0000000000000000 ffffffff81e11500 ffff8802126c3700
[ 3240.018827] ffff880213c08000 ffff880212669a24 ffff8802126c3700 00000000ffffffff
[ 3240.018829] ffff880212669a28 ffff880213c07a00 ffffffff81830f15 ffff880212669a20
[ 3240.018831] Call Trace:
[ 3240.018833] [<ffffffff81830f15>] schedule+0x35/0x80
[ 3240.018834] [<ffffffff818311be>] schedule_preempt_disabled+0xe/0x10
[ 3240.018836] [<ffffffff81832df9>] __mutex_lock_slowpath+0xb9/0x130
[ 3240.018838] [<ffffffff81832e8f>] mutex_lock+0x1f/0x30
[ 3240.018848] [<ffffffffc047a70d>] cifs_reconnect_tcon+0x9d/0x340 [cifs]
[ 3240.018850] [<ffffffff811eb999>] ? ___slab_alloc+0x1e9/0x470
[ 3240.018860] [<ffffffffc047aa5a>] smb_init+0x2a/0x50 [cifs]
[ 3240.018869] [<ffffffffc0481c53>] CIFSSMBQPathInfo+0x63/0x2e0 [cifs]
[ 3240.018875] [<ffffffff811aeb4c>] ? zone_statistics+0x7c/0xa0
[ 3240.018886] [<ffffffffc04ad14f>] cifs_query_path_info+0x6f/0x1a0 [cifs]
[ 3240.018889] [<ffffffff81218b84>] ? lookup_fast+0x184/0x330
[ 3240.018891] [<ffffffff811ebf23>] ? kmem_cache_alloc_trace+0x183/0x1f0
[ 3240.018893] [<ffffffff81218b84>] ? lookup_fast+0x184/0x330
[ 3240.018903] [<ffffffffc049bdc0>] cifs_get_inode_info+0x390/0x8f0 [cifs]
[ 3240.018906] [<ffffffff81218971>] ? unlazy_walk+0xc1/0x150
[ 3240.018908] [<ffffffff811ed5b9>] ? __kmalloc+0x1b9/0x250
[ 3240.018918] [<ffffffffc048edb2>] ? build_path_from_dentry+0xe2/0x3e0 [cifs]
[ 3240.018927] [<ffffffffc048edb2>] ? build_path_from_dentry+0xe2/0x3e0 [cifs]
[ 3240.018937] [<ffffffffc049e365>] cifs_revalidate_dentry_attr+0x1d5/0x250 [cifs]
[ 3240.018939] [<ffffffff811ec1a7>] ? kmem_cache_alloc+0x187/0x1f0
[ 3240.018949] [<ffffffffc049e491>] cifs_getattr+0x51/0x110 [cifs]
[ 3240.018951] [<ffffffff812126cc>] vfs_getattr_nosec+0x2c/0x40
[ 3240.018953] [<ffffffff812128e6>] vfs_getattr+0x26/0x30
[ 3240.018954] [<ffffffff812129c8>] vfs_fstatat+0x78/0xc0
[ 3240.018956] [<ffffffff81212f0e>] SYSC_newstat+0x2e/0x60
[ 3240.018960] [<ffffffff81003226>] ? exit_to_usermode_loop+0xa6/0xd0
[ 3240.018961] [<ffffffff8121309e>] SyS_newstat+0xe/0x10
[ 3240.018963] [<ffffffff81834ff2>] entry_SYSCALL_64_fastpath+0x16/0x71

running Ubuntu 16.04 (4.4.0-47-generic #68-Ubuntu SMP Wed Oct 26 19:39:52 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux) and running in a virtual box VM.