Re: [PATCH 08/10] parisc: fix livelock in uaccess

Al Viro
2023-02-28T19:14:15Z

On Tue, Feb 28, 2023 at 07:26:48PM +0100, Helge Deller wrote:

> I can test both parisc32 and parisc64.
>
> > Just to confirm: your "can be killed with ^C" had been on the
> > mainline parisc kernel (with userfaultfd enable, of course, or it wouldn't
> > hang up at all), right?
>
> It was a recent mainline kernel with your patch.

Er... Reproducer *is* supposed to block; the bug is that on the kernel
without this patch it would (AFAICS) be impossible to kill - not even
with kill -9. With bug fixed the behaviour should be "blocks and is
killable", i.e. what you've reported.

What does it do on unpatched kernel? *IF* the big is there, it would
block and be unkillable by any means. Could you verify that?