Re: [PATCH] mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified

[Yang Shi]

On 3/19/19 5:49 PM, David Rientjes wrote:
> On Wed, 20 Mar 2019, Yang Shi wrote:
>
> > When MPOL_MF_STRICT was specified and an existing page was already
> > on a node that does not follow the policy, mbind() should return -EIO.
> > But commit 6f4576e3687b ("mempolicy: apply page table walker on
> > queue_pages_range()") broke the rule.
> >
> > And, commit c8633798497c ("mm: mempolicy: mbind and migrate_pages
> > support thp migration") didn't return the correct value for THP mbind()
> > too.
> >
> > If MPOL_MF_STRICT is set, ignore vma_migratable() to make sure it reaches
> > queue_pages_to_pte_range() or queue_pages_pmd() to check if an existing
> > page was already on a node that does not follow the policy.  And,
> > non-migratable vma may be used, return -EIO too if MPOL_MF_MOVE or
> > MPOL_MF_MOVE_ALL was specified.
> >
> > Tested with https://github.com/metan-ucw/ltp/blob/master/testcases/kernel/syscalls/mbind/mbind02.c
> >
> > Fixes: 6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
> > Reported-by: Cyril Hrubis <chrubis@xxxxxxx>
> > Cc: Vlastimil Babka <vbabka@xxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > Suggested-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> > Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> > Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
>
> Thanks.  I think this needs stable for 4.0+, can you confirm?

Thanks. Yes, this needs stable for 4.0+.

Yang