Re: [v4 PATCH 2/2] mm: mempolicy: handle vma with unmovable pages mapped correctly in mbind

On 7/23/19 7:35 AM, Yang Shi wrote:

On 7/22/19 6:02 PM, Andrew Morton wrote:

quoted

On Mon, 22 Jul 2019 09:25:09 +0200 Vlastimil Babka [off-list ref] wrote:

quoted

quoted

since there may be pages off LRU temporarily.  We should migrate other
pages if MPOL_MF_MOVE* is specified.  Set has_unmovable flag if some
paged could not be not moved, then return -EIO for mbind() eventually.

With this change the above test would return -EIO as expected.

Cc: Vlastimil Babka <redacted>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <redacted>
Signed-off-by: Yang Shi <redacted>

Reviewed-by: Vlastimil Babka <redacted>

Thanks.

I'm a bit surprised that this doesn't have a cc:stable.  Did we
consider that?

The VM_BUG just happens on 4.9, and it is enabled only by CONFIG_VM. For 
post-4.9 kernel, this fixes the semantics of mbind which should be not a 
regression IMHO.

4.9 is a LTS kernel, so perhaps worth trying?

quoted

Also, is this patch dependent upon "mm: mempolicy: make the behavior
consistent when MPOL_MF_MOVE* and MPOL_MF_STRICT were specified"?
Doesn't look that way..

No, it depends on patch #1.

quoted

Also, I have a note that you had concerns with "mm: mempolicy: make the
behavior consistent when MPOL_MF_MOVE* and MPOL_MF_STRICT were
specified".  What is the status now?

Vlastimil had given his Reviewed-by.

Yes, the concerns were resolved.