[PATCH V2 0/2] block: fix race between adding wbt and normal IO

Hello,

Yi reported several kernel panics on:

[16687.001777] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
...
[16687.163549] pc : __rq_qos_track+0x38/0x60

or

[  997.690455] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
...
[  997.850347] pc : __rq_qos_done+0x2c/0x50

Turns out it is caused by race between adding wbt and normal IO.

Fix the issue by freezing request queue when adding/deleting rq qos.

V2:
	- switch to the approach of freezing queue, which is more generic
	  than V1.


Ming Lei (2):
  block: fix race between adding/removing rq qos and normal IO
  block: mark queue init done at the end of blk_register_queue

 block/blk-rq-qos.h | 13 +++++++++++++
 block/blk-sysfs.c  | 29 +++++++++++++++--------------
 2 files changed, 28 insertions(+), 14 deletions(-)

Cc: Yi Zhang <redacted>
Cc: Bart Van Assche <bvanassche@acm.org>
-- 
2.31.1