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...
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