lockdep WARNING at blktests block/011

[Tetsuo Handa]

On 2022/10/04 19:44, Shinichiro Kawasaki wrote:
> Any comment on this patch will be appreciated. If this action approach is ok,
> I'll post as a formal patch for review.

I don't want you to make such change.

I saw a case where real deadlock was hidden by lockdep_set_novalidate_class().

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=62ebaf2f9261cd2367ae928a39343fcdbfe9f877
  https://groups.google.com/g/syzkaller-bugs/c/Uj9LqEUCwac/m/BhdTjWhNAQAJ

In general, this kind of deadlock possibility had better be addressed by bringing
problematic locks out of cancel{,_delayed}_work_sync() section.

  https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=a91b750fd6629354460282bbf5146c01b05c4859