Odd SIGSEGV issue introduced by commit 6b31d5955cb29 ("mm, oom: fix potential data corruption when oom_reaper races with writer")

[Michael Ellerman]

Christophe LEROY <christophe.leroy at c-s.fr> writes:
...
>
> And I bisected its disappearance with commit 99cd1302327a2 ("powerpc: 
> Deliver SEGV signal on pkey violation")

Whoa that's weird.

> Looking at those two commits, especially the one which makes it 
> dissapear, I'm quite sceptic. Any idea on what could be the cause and/or 
> how to investigate further ?

Are you sure it's not some corruption that just happens to be masked by
that commit? I can't see anything in that commit that could explain that
change in behaviour.

The only real change is if you're hitting DSISR_KEYFAULT isn't it?

What happens if you take 087003e9ef7c and apply the various hunks from
99cd1302327a2 gradually (or those that you can anyway)?

cheers