linux-kernel - Re: [GIT PULL] Networking for v6.16-rc6 (follow up)

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Message-ID: <CAHk-=wiMJWwgJ4HYsLzJ4_OkhzJ75ah0HrfBBk+W-RGjk4-h2g@mail.gmail.com>
Date: Fri, 11 Jul 2025 15:19:00 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Jakub Kicinski <kuba@...nel.org>, Frederic Weisbecker <frederic@...nel.org>, 
	Valentin Schneider <vschneid@...hat.com>, Nam Cao <namcao@...utronix.de>, 
	Christian Brauner <brauner@...nel.org>
Cc: Thomas Zimmermann <tzimmermann@...e.de>, Simona Vetter <simona@...ll.ch>, 
	Dave Airlie <airlied@...il.com>, davem@...emloft.net, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, pabeni@...hat.com, 
	dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [GIT PULL] Networking for v6.16-rc6 (follow up)

On Fri, 11 Jul 2025 at 14:46, Linus Torvalds
<torvalds@...ux-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.

               Linus