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

[Yang Shi]

On 7/24/19 5:44 PM, Andrew Morton wrote:
> On Wed, 24 Jul 2019 10:19:34 +0200 Vlastimil Babka <vbabka@xxxxxxx> wrote:
>
> > On 7/23/19 7:35 AM, Yang Shi wrote:
> > > On 7/22/19 6:02 PM, Andrew Morton wrote:
> > > > On Mon, 22 Jul 2019 09:25:09 +0200 Vlastimil Babka <vbabka@xxxxxxx> wrote:
> > > >
> > > > > > 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 <vbabka@xxxxxxx>
> > > > > > Cc: Michal Hocko <mhocko@xxxxxxxx>
> > > > > > Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> > > > > > Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> > > > > Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> > > > 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?
> OK, I'll add cc:stable to

Thanks.

> mm-mempolicy-make-the-behavior-consistent-when-mpol_mf_move-and-mpol_mf_strict-were-specified.patch
>
> and
>
> mm-mempolicy-handle-vma-with-unmovable-pages-mapped-correctly-in-mbind.patch
>
> Do we have a Fixes: for these patches?

It looks the problem has existed since very beginning. The oldest commit 
which I can find is dc9aa5b9d65fd11b1f5246b46ec610ee8b83c6dd ("[PATCH] 
Swap Migration V5: MPOL_MF_MOVE interface"), which is a 2.6.16 commit.