Scratch that. This just happened to me again (apparently, it does not happen EVERY time).

Here the the backtrace:
[37574.918677] Freezing of tasks failed after 20.01 seconds (1 tasks refusing to freeze, wq_busy=0):
[37574.918720] dolphin         D f0fc8dd8     0  2282      1 0x00800004
[37574.918727]  ed131d48 00200086 ed131d38 f0fc8dd8 00200246 ffffffdc f048ce4c c1877680
[37574.918735]  5b34265f 00002227 f048ce48 c1877680 c1877680 f7887680 f048cbc0 f74d3280
[37574.918742]  ed131d68 ffffffa8 ed131d60 fee1ee47 00000001 0000004e 00000010 ed131d1c
[37574.918750] Call Trace:
[37574.918772]  [<fee1ee47>] ? smb_sendv+0xe7/0x310 [cifs]
[37574.918780]  [<c1035908>] ? default_spin_lock_flags+0x8/0x10
[37574.918787]  [<c15319af>] ? _raw_spin_lock_irqsave+0x2f/0x50
[37574.918793]  [<c1076ed8>] ? prepare_to_wait+0x48/0x70
[37574.918804]  [<fee1f14f>] wait_for_response.clone.1+0x6f/0xb0 [cifs]
[37574.918806]  [<c1076c70>] ? autoremove_wake_function+0x0/0x50
[37574.918812]  [<fee1fdbd>] SendReceive+0x17d/0x370 [cifs]
[37574.918817]  [<fee07732>] CIFSSMBUnixQPathInfo+0x122/0x280 [cifs]
[37574.918823]  [<fee1a461>] cifs_get_inode_info_unix+0x71/0x190 [cifs]
[37574.918827]  [<c113c6fd>] ? dget+0x2d/0x40
[37574.918829]  [<c113c986>] ? follow_managed+0xb6/0xe0
[37574.918831]  [<c113d3d5>] ? do_lookup+0xe5/0x260
[37574.918835]  [<c114b449>] ? vfsmount_lock_local_unlock+0x19/0x20
[37574.918838]  [<c114ca9d>] ? mntput_no_expire+0x2d/0xd0
[37574.918840]  [<c114cb58>] ? mntput+0x18/0x30
[37574.918845]  [<fee118d5>] ? build_path_from_dentry+0xc5/0x1e0 [cifs]
[37574.918849]  [<fee118d5>] ? build_path_from_dentry+0xc5/0x1e0 [cifs]
[37574.918854]  [<fee1197a>] ? build_path_from_dentry+0x16a/0x1e0 [cifs]
[37574.918856]  [<c153180d>] ? _raw_spin_lock+0xd/0x10
[37574.918862]  [<fee1cb08>] ? _GetXid+0x58/0x80 [cifs]
[37574.918867]  [<fee1b881>] cifs_revalidate_dentry+0xd1/0x1c0 [cifs]
[37574.918871]  [<c1287832>] ? copy_to_user+0x42/0x60
[37574.918876]  [<fee1b9a3>] cifs_getattr+0x33/0xc0 [cifs]
[37574.918879]  [<c1136822>] vfs_getattr+0x42/0x70
[37574.918884]  [<fee1b970>] ? cifs_getattr+0x0/0xc0 [cifs]
[37574.918886]  [<c11368bd>] vfs_fstatat+0x6d/0x90
[37574.918888]  [<c1136900>] vfs_lstat+0x20/0x30
[37574.918890]  [<c1136cd6>] sys_lstat64+0x16/0x30
[37574.918893]  [<c100ab5f>] sysenter_do_call+0x12/0x28
[37574.918896]  [<c1530000>] ? schedule_timeout+0x180/0x260
[37574.918903] kblankscrn.kss  T 00040005     0 17203  17201 0x00800004
[37574.918906]  ecaa9e8c 00200086 00000000 00040005 00004333 000003e8 f043742c c1877680
[37574.918909]  bb239133 00002227 f0437428 c1877680 c1877680 f78c7680 f04371a0 f74d6500
[37574.918913]  f69d4630 f69d463c 00000000 ecaa9e54 c1068ce2 00000013 f04371a0 f043752c
[37574.918916] Call Trace:
[37574.918920]  [<c1068ce2>] ? __sigqueue_free+0x32/0x40
[37574.918922]  [<c1069747>] ? recalc_sigpending+0x17/0x40
[37574.918924]  [<c1069b18>] ? dequeue_signal+0xb8/0x190
[37574.918926]  [<c106a7a2>] do_signal_stop+0xa2/0x1c0
[37574.918929]  [<c106b661>] get_signal_to_deliver+0x101/0x360
[37574.918931]  [<c100a4b1>] do_signal+0x61/0x120
[37574.918934]  [<c113251c>] ? rw_verify_area+0x6c/0x130
[37574.918936]  [<c1132abe>] ? vfs_read+0x14e/0x160
[37574.918938]  [<c100a7b5>] do_notify_resume+0x75/0x90
[37574.918940]  [<c1531d00>] work_notifysig+0x13/0x1b