Re: add_wait_queue() (unintentional?) behavior change in v4.13

[Ingo Molnar]

* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Wed, Nov 29, 2017 at 4:58 PM, Omar Sandoval <osandov@xxxxxxxxxxx> wrote:
> >
> > Note the change from __add_wait_queue() to
> > __add_wait_queue_entry_tail(). I'm assuming this was a typo since the
> > commit message doesn't mention any functional changes. This patch
> > restores the old behavior:
> >   [...]
> > I didn't go through and audit callers of add_wait_queue(), but from a
> > quick code read this makes it so that non-exclusive waiters will not be
> > woken up if they are behind enough exclusive waiters, and I bet that'll
> > cause some bugs.
> 
> This sounds right to me.
> 
> Ingo?

Yeah, it's indeed unintended and it's a bug - I have applied the fix and will get 
it to you ASAP.

Thanks,

	Ingo