qemu:metag image runtime failure in -next due to 'kthread: allow to cancel kthread work'

[Guenter Roeck <linux@roeck-us.net>]

Hi,

I see the following runtime error in -next when running a metag qemu emulation.

[ ... ]
workingset: timestamp_bits=30 max_order=16 bucket_order=0
io scheduler noop registered (default)
brd: module loaded
Warning: unable to open an initial console.
List of all partitions:
0100           16384 ram0  (driver?)
No filesystem could mount root, tried: 
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)

An example for a complete log is at:
http://kerneltests.org/builders/qemu-metag-next/builds/489/steps/qemubuildcommand/logs/stdio

bisect points to commit ef98de028afde ("kthread: allow to cancel kthread work").
I don't know (yet) if other architectures are affected. bisect log is attached.

The scripts to run this test are available at
https://github.com/groeck/linux-build-test/tree/master/rootfs/metag.

Guenter

--
# bad: [ddf9d15aed5ba5786cf4b082576c44ce37cd29c2] Add linux-next specific files for 20160916
# good: [9395452b4aab7bc2475ef8935b4a4fb99d778d70] Linux 4.8-rc6
git bisect start 'HEAD' 'v4.8-rc6'
# good: [03593c66538f0dd2c46f14dfdd9c7c0b96d12163] Merge remote-tracking branch 'crypto/master'
git bisect good 03593c66538f0dd2c46f14dfdd9c7c0b96d12163
# good: [144ff127c1a802bc466cd9fe64033682193c0831] Merge remote-tracking branch 'edac-amd/for-next'
git bisect good 144ff127c1a802bc466cd9fe64033682193c0831
# good: [cfab536f2992d0db27424f146cf0e13bb4a2c0c4] Merge remote-tracking branch 'staging/staging-next'
git bisect good cfab536f2992d0db27424f146cf0e13bb4a2c0c4
# good: [f185e7dd5ed5eb7e1a834bde8ad6ea1393737037] Merge remote-tracking branch 'gpio/for-next'
git bisect good f185e7dd5ed5eb7e1a834bde8ad6ea1393737037
# good: [a69892f0ba574e71154f8c5c647626a7dd065ce5] ipc-msg-avoid-waking-sender-upon-full-queue-checkpatch-fixes
git bisect good a69892f0ba574e71154f8c5c647626a7dd065ce5
# good: [209370566ef8c38dcea40561db2c46fadb0078ce] Merge tag 'clk-renesas-for-v4.9-tag3' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers into clk-next
git bisect good 209370566ef8c38dcea40561db2c46fadb0078ce
# good: [be3400244f19bb16b16b5dd32d8719e59790f361] Merge remote-tracking branch 'coresight/next'
git bisect good be3400244f19bb16b16b5dd32d8719e59790f361
# good: [513d99d37db2a9ceb489e7123fb1458b29eeafff] Merge remote-tracking branch 'nvdimm/libnvdimm-for-next'
git bisect good 513d99d37db2a9ceb489e7123fb1458b29eeafff
# good: [9101ca3b2763583e10ec93a453363a8af3ced438] kthread: add kthread_create_worker*()
git bisect good 9101ca3b2763583e10ec93a453363a8af3ced438
# bad: [57169cae0bc5472d9d3eee5c0923ae6d5ae8d299] kthread: better support freezable kthread workers
git bisect bad 57169cae0bc5472d9d3eee5c0923ae6d5ae8d299
# good: [5c204b8f9b8f30bf641095f4005fa320cd192254] kthread: initial support for delayed kthread work
git bisect good 5c204b8f9b8f30bf641095f4005fa320cd192254
# bad: [26242e2b569d11fbbfdf40c93d9d11329825724a] kthread: allow to modify delayed kthread work
git bisect bad 26242e2b569d11fbbfdf40c93d9d11329825724a
# bad: [ef98de028afde6861712a208b0e25f6b6af3912a] kthread: allow to cancel kthread work
git bisect bad ef98de028afde6861712a208b0e25f6b6af3912a
# first bad commit: [ef98de028afde6861712a208b0e25f6b6af3912a] kthread: allow to cancel kthread work