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Date:   Thu, 28 Sep 2023 09:38:09 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Suren Baghdasaryan <surenb@google.com>
Cc:     Yang Shi <yang@os.amperecomputing.com>, hughd@google.com,
        willy@infradead.org, mhocko@suse.com, vbabka@suse.cz,
        osalvador@suse.de, aquini@redhat.com, kirill@shutemov.name,
        rientjes@google.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] mm: mempolicy: keep VMA walk if both MPOL_MF_STRICT and
 MPOL_MF_MOVE are specified
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On Wed, 27 Sep 2023 14:39:21 -0700 Suren Baghdasaryan <surenb@google.com> wrote:

> > >
> > >> The code should conceptually do:
> > >>
> > >>   if (MPOL_MF_MOVE|MOVEALL)
> > >>       scan all vmas
> > >>       try to migrate the existing pages
> > >>       return success
> > >>   else if (MPOL_MF_MOVE* | MPOL_MF_STRICT)
> > >>       scan all vmas
> > >>       try to migrate the existing pages
> > >>       return -EIO if unmovable or migration failed
> > >>   else /* MPOL_MF_STRICT alone */
> > >>       break early if meets unmovable and don't call mbind_range() at all
> > >>   else /* none of those flags */
> > >>       check the ranges in test_walk, EFAULT without mbind_range() if discontig.
> 
> With this change I think my temporary fix at
> https://lore.kernel.org/all/20230918211608.3580629-1-surenb@google.com/
> can be removed because we either scan all vmas (which means we locked
> them all) or we break early and do not call mbind_range() at all (in
> which case we don't need vmas to be locked).

Thanks, I dropped "mm: lock VMAs skipped by a failed queue_pages_range()"