On Wed, Aug 21, 2024 at 12:10:17PM -0400, Zi Yan wrote:
> When handling a numa page fault, task_numa_fault() should be called by a
> process that restores the page table of the faulted folio to avoid
> duplicated stats counting. Commit b99a342d4f11 ("NUMA balancing: reduce
> TLB flush via delaying mapping on hint page fault") restructured
> do_numa_page() and did not avoid task_numa_fault() call in the second page
> table check after a numa migration failure. Fix it by making all
> !pte_same() return immediately.
>
> This issue can cause task_numa_fault() being called more than necessary
> and lead to unexpected numa balancing results (It is hard to tell whether
> the issue will cause positive or negative performance impact due to
> duplicated numa fault counting).
>
> Link: https://lkml.kernel.org/r/20240809145906.1513458-2-ziy@xxxxxxxxxx
> Fixes: b99a342d4f11 ("NUMA balancing: reduce TLB flush via delaying mapping on hint page fault")
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
> Reported-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Closes: https://lore.kernel.org/linux-mm/87zfqfw0yw.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Yang Shi <shy828301@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> (cherry picked from commit 40b760cfd44566bca791c80e0720d70d75382b84)
> ---
> mm/memory.c | 29 ++++++++++++++---------------
> 1 file changed, 14 insertions(+), 15 deletions(-)
All now queued up, thanks.
greg k-h
