Re: periodically-drain-non-local-pagesets-fix.patch added to -mm

[Andrew Morton <akpm@osdl.org>]

Keith Owens <kaos@sgi.com> wrote:
>
> On Fri, 3 Jun 2005 00:22:10 -0700, 
> Andrew Morton <akpm@osdl.org> wrote:
> >Keith Owens <kaos@sgi.com> wrote:
> >> Does this fix the problem?  Compiled but not tested.
> >
> >Well it'll make the warning go away but I think there's a more fundamental
> >problem, in that:
> >
> >	get_cpu();
> >	cond = something_which_uses_smp_processor_id();
> >	put_cpu();
> >
> >	/* `cond' can become false at any time from here */
> 
> Good point.  The entire fpu load/restore logic on ia64 needs reviewing
> for preemption.  There is an implicit assumption that the fpu state is
> atomically saved and restored on the current cpu, while under the
> control of psr->mfh.  Preempt has the potential to migrate a task while
> it is in the middle of save/restore fpu, breaking that assumption.
> Other ia64 register save/restore code might have similar problems.

OK, thanks.  Could someone please spin up a disable-preempt-on-ia64 patch
for the 2.6.12 release?

> Leaving this one to the rest of the list.

Sensible man ;)