Comment 5 for bug 1073648

I am having the same problem on ubuntu 16.04.2, kernel 4.4.0-75-generic, and on a mint 18 system, kernel 4.4.0-21-generic. I have several cifs mounts, and if any one server becomes unresponsive, then any process attempting to access the mounts will hang indefinitely. If I unmount using -l and wait several minutes, eventually these hung processes will resume (with an error). I am mounting with the "soft" option.

The hung process stack looks like:
$ sudo cat /proc/7771/stack
[<ffffffffc030970d>] cifs_reconnect_tcon+0x9d/0x340 [cifs]
[<ffffffffc0309a5a>] smb_init+0x2a/0x50 [cifs]
[<ffffffffc0310c53>] CIFSSMBQPathInfo+0x63/0x2e0 [cifs]
[<ffffffffc033c20f>] cifs_query_path_info+0x6f/0x1a0 [cifs]
[<ffffffffc032ae80>] cifs_get_inode_info+0x390/0x8f0 [cifs]
[<ffffffffc032d425>] cifs_revalidate_dentry_attr+0x1d5/0x250 [cifs]
[<ffffffffc032d551>] cifs_getattr+0x51/0x110 [cifs]
[<ffffffff81213a6c>] vfs_getattr_nosec+0x2c/0x40
[<ffffffff81213c86>] vfs_getattr+0x26/0x30
[<ffffffff81213d68>] vfs_fstatat+0x78/0xc0
[<ffffffff81214311>] SYSC_newlstat+0x31/0x60
[<ffffffff8121444e>] SyS_newlstat+0xe/0x10
[<ffffffff8183b972>] entry_SYSCALL_64_fastpath+0x16/0x71
[<ffffffffffffffff>] 0xffffffffffffffff