Re: [PATCH v2 0/4] x86: sigcontext fixes, again

[Toshi Kani]

On Wed, 2015-10-28 at 07:37 +0900, Linus Torvalds wrote:
> On Tue, Oct 27, 2015 at 11:05 PM, Stas Sergeev <stsp@xxxxxxx> wrote:
> > 
> > I can't easily post an Oops: under X it doesn't even appear -
> > machine freezes immediately, and under non-KMS console it is
> > possible to get one, but difficult to screen-shot (using bare
> > metal, not VM). Also the Oops was seemingly unrelated.
> > And if you run "dosemu -s" under non-KMS console, you'll also
> > reproduce this one:
> > https://bugzilla.kernel.org/show_bug.cgi?id=97321
> 
> Hmm. Andrew Morton responded to that initially, but then nothing
> happened, and now it's been another six months. Andrew?
> 
> The arch/x86/mm/pat.c error handling does seem to be suspect. This is
> all code several years old, so none of this is new, and I think Suresh
> is gone.  Adding a few other people with recent sign-offs to that
> file, in the hope that somebody feels like they own it..

In the case of PFNMAP, the range should always be mapped.  So, I wonder why
follow_phys() failed with the !pte_present() check.

Stas, do you have a test program that can reproduce 97321?

-Toshi
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