Re: [PATCH 14/15] mm: numa: Flush TLB if NUMA hinting faults racewith PTE scan update

From: Mel Gorman
Date: Tue Dec 03 2013 - 18:46:50 EST


On Tue, Dec 03, 2013 at 06:07:06PM -0500, Rik van Riel wrote:
> On 12/03/2013 03:52 AM, Mel Gorman wrote:
> > NUMA PTE updates and NUMA PTE hinting faults can race against each other. The
> > setting of the NUMA bit defers the TLB flush to reduce overhead. NUMA
> > hinting faults do not flush the TLB as X86 at least does not cache TLB
> > entries for !present PTEs. However, in the event that the two race a NUMA
> > hinting fault may return with the TLB in an inconsistent state between
> > different processors. This patch detects potential for races between the
> > NUMA PTE scanner and fault handler and will flush the TLB for the affected
> > range if there is a race.
> >
> > Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
>
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index 5dfd552..ccc814b 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -1662,6 +1662,39 @@ void wait_migrate_huge_page(struct anon_vma *anon_vma, pmd_t *pmd)
> > smp_rmb();
> > }
> >
> > +unsigned long numa_fault_prepare(struct mm_struct *mm)
> > +{
> > + /* Paired with task_numa_work */
> > + smp_rmb();
> > + return mm->numa_next_reset;
> > +}
>
> The patch that introduces mm->numa_next_reset, and the
> patch that increments it, seem to be missing from your
> series...
>

Damn. s/numa_next_reset/numa_next_scan/ in that patch

--
Mel Gorman
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/