Comment 12 for bug 752012

my backtrace:
[32467.560058] Freezing of tasks failed after 20.01 seconds (1 tasks refusing to freeze, wq_busy=0):
[32467.560115] plasma-desktop D 0000000000000000 0 2065 1 0x00800004
[32467.560120] ffff88005c529958 0000000000000082 ffff88005c529fd8 ffff88005c528000
[32467.560123] 0000000000013d00 ffff8800649c3178 ffff88005c529fd8 0000000000013d00
[32467.560126] ffffffff81a0b020 ffff8800649c2dc0 ffff880061f40448 ffff88006447bab8
[32467.560130] Call Trace:
[32467.560149] [<ffffffffa016d731>] wait_for_response.clone.1+0x81/0xd0 [cifs]
[32467.560155] [<ffffffff81087f00>] ? autoremove_wake_function+0x0/0x40
[32467.560163] [<ffffffffa016e523>] SendReceive+0x1a3/0x3b0 [cifs]
[32467.560169] [<ffffffffa0153c79>] CIFSSMBUnixQPathInfo+0x139/0x2b0 [cifs]
[32467.560176] [<ffffffffa016853d>] cifs_get_inode_info_unix+0x7d/0x1a0 [cifs]
[32467.560180] [<ffffffff814ba2da>] ? sock_poll+0x1a/0x20
[32467.560184] [<ffffffff8117758e>] ? do_poll.clone.2+0x22e/0x290
[32467.560190] [<ffffffffa015f240>] ? build_path_from_dentry+0xf0/0x230 [cifs]
[32467.560196] [<ffffffffa015f2f7>] ? build_path_from_dentry+0x1a7/0x230 [cifs]
[32467.560203] [<ffffffffa0169a1a>] cifs_revalidate_dentry+0xfa/0x1e0 [cifs]
[32467.560209] [<ffffffffa015f102>] cifs_d_revalidate+0x22/0x70 [cifs]
[32467.560212] [<ffffffff8116f007>] do_revalidate+0x17/0x60
[32467.560215] [<ffffffff81171556>] do_lookup+0x236/0x2e0
[32467.560217] [<ffffffff8116eec3>] ? generic_permission+0x23/0xc0
[32467.560220] [<ffffffff81171766>] link_path_walk+0x166/0xc40
[32467.560223] [<ffffffff811770b0>] ? pollwake+0x0/0x60
[32467.560226] [<ffffffff8117253b>] do_path_lookup+0x5b/0x160
[32467.560229] [<ffffffff811728a7>] user_path_at+0x57/0xa0
[32467.560234] [<ffffffff81169599>] vfs_fstatat+0x39/0x70
[32467.560237] [<ffffffff8116960b>] vfs_stat+0x1b/0x20
[32467.560240] [<ffffffff8116984a>] sys_newstat+0x1a/0x40
[32467.560243] [<ffffffff81164fa7>] ? vfs_read+0x167/0x180
[32467.560245] [<ffffffff8116503c>] ? sys_read+0x7c/0x90
[32467.560249] [<ffffffff8100c002>] system_call_fastpath+0x16/0x1b