On Tue, Aug 21, 2018 at 04:40:15PM +1000, Michael Ellerman wrote:

Christophe LEROY [off-list ref] writes:
...

quoted

And I bisected its disappearance with commit 99cd1302327a2 ("powerpc: 
Deliver SEGV signal on pkey violation")

Whoa that's weird.

quoted

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?

even with the 'commit 99cd1302327a2', a SEGV signal should get generated;
which should kill the process. Unless the process handles SEGV signals 
with SEGV_PKUERR differently.

The other surprising thing is, why is DSISR_KEYFAULT getting generated
in the first place?  Are keys somehow getting programmed into the HPTE?

Feels like some random corruption.

Is this behavior seen with power8 or power9?

RP