On Fri, Jul 11, 2025 at 03:19:00PM -0700, Linus Torvalds wrote:
> On Fri, 11 Jul 2025 at 14:46, Linus Torvalds
> <torva...@linux-foundation.org> wrote:
> >
> > I've only tested the previous commit being good twice now, but I'll go
> > back to the head of tree and try a revert to verify that this is
> > really it. Because maybe it's the now Nth time I found something that
> > hides the problem, not the real issue.
> >
> > Fingers crossed that this very timing-dependent odd problem really did
> > bisect right finally, after many false starts.
>
> Ok, verified. Finally.
>
> I've rebooted this machine five times now with the revert in place,
> and now that I know to recognize all the subtler signs of breakage,
> I'm pretty sure I finally got the right culprit.
>
> Sometimes the breakage is literally just something like "it takes an
> extra ten or fifteen seconds to start up some app" and then everything
> ends up working, which is why it was so easy to overlook, and why my
> other bisection attempts were such abject failures.
>
> But that last bisection when I was more careful and knew what to look
> for ended up laser-guided to that thing.
>
> And apologies to the drm and netlink people who I initially blamed
> just because there were unrelated bugs that just got merged in the
> timeframe when I started noticing oddities. You may have had your own
> bugs, but you were blameless on this issue that I basically spent the
> last day on (I'd say "wasted" the last day on, but right now I feel
> good about finding it, so I guess it wasn't wasted time after all).
>
> Anyway, I think reverting that commit 8c44dac8add7 ("eventpoll: Fix
> priority inversion problem") is the right thing for 6.16, and
> hopefully Nam Cao & co can figure out what went wrong and we'll
> revisit this in the future.
Yes, please revert it. I had another person reported to me earlier today
about a breakage. We also think that reverting this commit for 6.16 is the
right thing.
Sorry for causing trouble. Strangely my laptop has been running with this
commit for ~6 weeks now without any trouble. Maybe I shouldn't have touched
this lockless business in the first place.
Best regards,
Nam
