Hello Liang,
On Thu, Jan 07, 2016 at 11:52:38AM +0800, Liang Chen wrote:
> MPOL_MF_LAZY is not visible from userspace since 'commit a720094ded8c
> ("mm: mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now")'
> , but it should still skip non-migratable VMAs such as VM_IO, VM_PFNMAP,
> and VM_HUGETLB VMAs, and avoid useless overhead of minor faults.
>
> Signed-off-by: Liang Chen <liangchen.linux@xxxxxxxxx>
> Signed-off-by: Gavin Guo <gavin.guo@xxxxxxxxxxxxx>
> ---
> Changes since v2:
> - Add more description into the changelog
>
> We have been evaluating the enablement of MPOL_MF_LAZY again, and found
> this issue. And we decided to push this patch upstream no matter if we
> finally determine to propose re-enablement of MPOL_MF_LAZY or not. Since
> it can be a potential problem even if MPOL_MF_LAZY is not enabled this
> time.
> ---
> mm/mempolicy.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 87a1779..436ff411 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -610,7 +610,8 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
>
> if (flags & MPOL_MF_LAZY) {
> /* Similar to task_numa_work, skip inaccessible VMAs */
> - if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
> + if (vma_migratable(vma) &&
> + vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
> change_prot_numa(vma, start, endvma);
> return 1;
> }
task_numa_work() does more vma checks before entering change_prot_numa() like
vma_policy_mof(), is_vm_hugetlb_page(), and (vma->vm_flags & VM_MIXEDMAP).
So is it better to use the same check set to limit the target vmas to auto-numa
enabled ones?
Thanks,
Naoya Horiguchi
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href