Re: [REGRESSION] v6.16 system hangs (bisected to nf_conntrack fix)

[Dan Moulding <dan@danm.net>]

> For some reason, I can no longer reproduce the problem in new kernels
> that I build. I can still reproduce it in the kernels that I built
> last week. But if I build a new one, from the same commit as I was
> able to reproduce it from before, the new kernel build can't reproduce
> it. I didn't change anything (like compiler version) since. So I'm
> stumped.

Well, I finally figured out why I couldn't reproduce the problem in
some builds. It turns out structure layout randomization was affecting
whether there was a bug or not. So every build I did had a chance of
not having the bug. This also led my bisection effort down the wrong
path and wrongly indicated that this nf_conntrack fix was the first
bad commit (and also by pure chance of randstruct made it look like
the problem went away when the change was reverted).

Now that I know that it's a randstruct problem, I was able to use a
"known bad" randstruct.seed to reliably make reproducible builds that
always have the bug, and this time correctly bisected it to a problem
in compression code in the cpypto API[1]. netfilter had nothing to do
with it. nf_conntrack is exonerated :)

So, Florian, sorry for taking up some of your valuable cycles on this
wild goose chase. But thank you for your attention and quick responses.

Cheers,

-- Dan

[1] https://lore.kernel.org/linux-crypto/20250830032839.11005-1-dan@danm.net/T/#t