Hi David,

I'm not sure if this is a good bisect because the errors are noisy,
however it's good to inform you of this possibility.

First bad commit may be a3483353c ("drm: check for !kdev in drm_unplug_minor()")

===================================================
PARENT COMMIT NOT CLEAN. LOOK OUT FOR WRONG BISECT!
===================================================

+------------------------------------------------------------------------------------+--------------+--------------+
|                                                                                    | 0846c728e20a | efb753b8e013 |
+------------------------------------------------------------------------------------+--------------+--------------+
| boot_successes                                                                     | 183          | 18           |
| boot_failures                                                                      | 162          | 11           |
| BUG:kernel_early_hang_without_any_printk_output                                    | 1            |              |
| BUG:unable_to_handle_kernel                                                        | 161          | 3            |
| BUG:unable_to_handle_kernel_NULL_pointer_dereferenceNULL_pointer_dereference_at    | 161          |              |
| Oops                                                                               | 161          | 3            |
| Oops:SMP_SMP_DEBUG_PAGEALLOCDEBUG_PAGEALLOC                                        | 161          | 3            |
| EIP_is_at_drm_unplug_minor                                                         | 161          |              |
| Kernel_panic-not_syncing:Fatal_exception                                           | 161          | 2            |
| BUG:spinlock_lockup_suspected_on_CPU                                               | 0            | 3            |
| INFO:NMI_handler(arch_trigger_all_cpu_backtrace_handler)took_too_long_to_run:msecs | 0            | 1            |
| BUG:unable_to_handle_kernel_paging_requestpaging_request_at                        | 0            | 3            |
| BUG:Bad_page_state_in_process                                                      | 0            | 1            |
| BUG:kernel_test_hang                                                               | 0            | 4            |
| EIP_is_at_default_send_IPI_mask_logical                                            | 0            | 3            |
| EIP_is_at_slob_free                                                                | 0            | 3            |
| EIP_is_at_drm_debugfs_cleanup                                                      | 0            | 1            |
| Kernel_panic-not_syncing:Fatal_exception_in_interrupt                              | 0            | 1            |
+------------------------------------------------------------------------------------+--------------+--------------+

[   12.071139] parport0: PC-style at 0x378
[   12.071139] parport0: PC-style at 0x378, irq 7, irq 7 [ [PCSPPPCSPP,TRISTATE,TRISTATE]
]
[   12.115335] BUG: spinlock lockup suspected on CPU#0, swapper/0/1

git bisect start 26b265cd29dde56bf0901c421eabc7ae815f38c4 v3.12 --
git bisect good 7e1a1e9378018aeea2c7e8a3dd2ceb1db1523b0b  # 23:43    115+      1  Merge tag 'xfs-for-linus-v3.13-rc1' of git://oss.sgi.com/xfs/xfs
git bisect  bad 13509c3a9d20a9df93dc9b944e8bd20fe1b454a7  # 23:58      3-      2  Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
git bisect  bad 4937e2a6f939a41bf811378e80d71f68aa0950c6  # 00:16      4-      4  Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
git bisect good 049ffa8ab33a63b3bff672d1a0ee6a35ad253fe8  # 01:04    115+     46  Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
git bisect good 98d38dd2ee30322fc9934d7490be3c5bee80950e  # 01:52    115+     51  Merge tag 'for-3.13' of git://git.openrisc.net/~jonas/linux
git bisect  bad f412f2c60b480fa5140a4b4cb321cd48c64e1812  # 02:06      0-      1  Merge branch 'for-linus' of git://git.kernel.dk/linux-block
git bisect good 6c0514ddd973ff13c3d2b2e7ac1422c982afb8eb  # 02:41    115+     43  Merge tag 'blackfin-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/realmz6/blackfin-linux
git bisect  bad cd1177f25069cb494680eedd718e7c6d8fd85d10  # 02:52      9-      4  Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
git bisect  bad a3483353ca4e6dbeef2ed62ebed01af109b5b27a  # 03:23      9-      2  drm: check for !kdev in drm_unplug_minor()
# first bad commit: [a3483353ca4e6dbeef2ed62ebed01af109b5b27a] drm: check for !kdev in drm_unplug_minor()
git bisect good 0846c728e20a0cd1e43fb75a3015f3b176a26466  # 06:05    345+    162  Merge branch 'drm-nouveau-next' of git://anongit.freedesktop.org/git/nouveau/linux-2.6 into drm-next
git bisect  bad efb753b8e0136fe66b507e8e1e42b5a2df7ba44d  # 06:05      0-     11  crypto: ixp4xx - Fix kernel compile error
git bisect good cf0c16eccacc7eaba6e710e553a7b5c0c39c6d70  # 09:20    345+    178  Revert "drm: check for !kdev in drm_unplug_minor()"
git bisect good 228fdc083b017eaf90e578fa86fb1ecfd5ffae87  # 11:23    345+      3  Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
git bisect good 1955a14a5ba6e3c3b11117812d11dc550ccc37ae  # 12:58    345+      0  Add linux-next specific files for 20140110

Thanks,
Fengguang