Hi Sergey, FYI here is another bisect result. The attached reproduce-* script may help reproduce the bug. https://github.com/0day-ci/linux/commits/Sergey-Senozhatsky/printk-introd... commit fbc14616f483788afabe77d05bfb99883dc66c73 Author: Sergey Senozhatsky <sergey.senozhatsky(a)gmail.com&gt; AuthorDate: Wed Mar 29 18:25:11 2017 +0900 Commit: 0day robot <fengguang.wu(a)intel.com&gt; CommitDate: Thu Mar 30 18:58:09 2017 +0800 printk: enable printk offloading Initialize the kernel printing thread and enable printk() offloading. Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky(a)gmail.com&gt; fd8b6b120c printk: add printk emergency_mode parameter fbc14616f4 printk: enable printk offloading fbc14616f4 printk: enable printk offloading +-------------------------------------------------+------------+------------+------------+ | | fd8b6b120c | fbc14616f4 | fbc14616f4 | +-------------------------------------------------+------------+------------+------------+ | boot_successes | 96 | 22 | 22 | | boot_failures | 0 | 13 | 13 | | BUG:kernel_reboot-without-warning_in_test_stage | 0 | 13 | 13 | +-------------------------------------------------+------------+------------+------------+ Kernel tests: Boot OK! [ 125.982508] Writes: Total: 2 Max/Min: 0/0 Fail: 0 [ 150.299255] Unregister pv shared memory for cpu 0 # HH:MM RESULT GOOD BAD GOOD_BUT_DIRTY DIRTY_NOT_BAD git bisect start 5809b48649bea3a3a6511b4393e2c73a670f7ad4 8f8ab14f4414e1be0e7c23036017e3e3130ba7cd -- git bisect good a8cd38c6c0b0a1543ab81ca37c740f4f86f085dc # 21:29 G 26 0 0 0 Merge 'hid/for-next' into devel-catchup-201703302001 git bisect bad d7261f07e7035243f09cb825895e8a6dcafe579c # 21:44 B 13 4 0 0 Merge 'linux-review/Sergey-Senozhatsky/printk-introduce-printing-kernel-thread/20170330-185752' into devel-catchup-201703302001 git bisect good 9dad6e22e1870cc1c426a374f5147c9374500dd7 # 10:28 G 30 0 0 0 Merge 'bpf/prog_test_run' into devel-catchup-201703302001 git bisect good 4fdb81c8aab9ba0d74fe86522f6def11d9ded0f1 # 10:40 G 31 0 0 0 Merge 'linux-review/Jan-Burgmeier/Fix-IB-va_start-ib_bytes-range-check-on-32Bit-systems/20170330-175723' into devel-catchup-201703302001 git bisect good da72040c4b25c8f8f0dfac045439da76983aea9c # 10:57 G 31 0 0 0 Merge 'linux-review/Alexey-Klimov/firmware-arm_scpi-reinit-completion-instead-of-full-init_completion/20170330-180533' into devel-catchup-201703302001 git bisect good 628e57e7b97e3f31e72917790122b0ef982e82c9 # 11:13 G 32 0 0 0 Merge 'linux-review/Shanker-Donthineni/ACPI-Update-platform-device-numa-node-based-on-_PXM-method/20170330-190738' into devel-catchup-201703302001 git bisect good 71b4c01c71544ce4e60ad2d2b97be5a2c9573d06 # 11:29 G 31 0 0 0 pm: switch to printk.emergency mode in unsafe places git bisect good 2ddfa6a93b77983c93cb47c75f555b6b420ec8f7 # 00:30 G 32 0 0 0 kexec: switch to printk.emergency mode in unsafe places git bisect bad fbc14616f483788afabe77d05bfb99883dc66c73 # 00:46 B 14 6 0 1 printk: enable printk offloading git bisect good fd8b6b120c9cc25f3d080388d47a3ea531389c64 # 01:02 G 30 0 0 0 printk: add printk emergency_mode parameter # first bad commit: [fbc14616f483788afabe77d05bfb99883dc66c73] printk: enable printk offloading git bisect good fd8b6b120c9cc25f3d080388d47a3ea531389c64 # 01:19 G 92 0 0 0 printk: add printk emergency_mode parameter # extra tests with CONFIG_DEBUG_INFO_REDUCED git bisect bad fbc14616f483788afabe77d05bfb99883dc66c73 # 01:33 B 16 4 0 0 printk: enable printk offloading # extra tests on HEAD of linux-devel/devel-catchup-201703302001 git bisect bad 5809b48649bea3a3a6511b4393e2c73a670f7ad4 # 01:39 B 9 3 0 2 0day head guard for 'devel-catchup-201703302001' # extra tests on tree/branch linux-review/Sergey-Senozhatsky/printk-introduce-printing-kernel-thread/20170330-185752 git bisect bad fbc14616f483788afabe77d05bfb99883dc66c73 # 01:42 B 20 13 0 0 printk: enable printk offloading # extra tests with first bad commit reverted git bisect good ad729515c32be2b77245ca5889bd079892b09324 # 02:03 G 33 0 0 0 Revert "printk: enable printk offloading" --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/lkp Intel Corporation