[v2,0/2] Fix a race condition triggered by submit_bio()

Message

Bart Van Assche July 30, 2019, 6:36 p.m. UTC

Hi Jens,

One of the consequences of the switch to blk-mq is that generic_make_request()
calls, a function called by submit_bio(), must be protected by a
blk_queue_enter() / blk_queue_exit() pair to avoid that the block-cgroup
functions called by generic_make_request() trigger a race condition. This patch
series makes the kernel report a warning if that race condition is hit and also
adds the necessary protection in submit_bio(). Please consider these patches
for kernel v5.4.

Thanks,

Bart.

Changes compared to v1:
- Use the full syzbot ID in patch 2/2 instead of abbreviating it.

Bart Van Assche (2):
  block: Verify whether blk_queue_enter() is used when necessary
  block: Fix a race condition in submit_bio()

 block/blk-cgroup.c         |  2 ++
 block/blk-core.c           | 34 +++++++++++++++++++++++++++++++++-
 include/linux/blk-cgroup.h |  2 ++
 include/linux/blkdev.h     |  8 ++++++++
 4 files changed, 45 insertions(+), 1 deletion(-)