[PATCH 4.4 006/168] mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified

[Greg Kroah-Hartman]

From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>

commit a7f40cfe3b7ada57af9b62fd28430eeb4a7cfcb7 upstream.

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

[akpm@xxxxxxxxxxxxxxxxxxxx: tweak code comment]
Link: http://lkml.kernel.org/r/1553020556-38583-1-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx
Fixes: 6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Reported-by: Cyril Hrubis <chrubis@xxxxxxx>
Suggested-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Acked-by: Rafael Aquini <aquini@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


---
 mm/mempolicy.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -514,12 +514,16 @@ static int queue_pages_pte_range(pmd_t *
 		if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
 			continue;
 
-		if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+		if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+			if (!vma_migratable(vma))
+				break;
 			migrate_page_add(page, qp->pagelist, flags);
+		} else
+			break;
 	}
 	pte_unmap_unlock(pte - 1, ptl);
 	cond_resched();
-	return 0;
+	return addr != end ? -EIO : 0;
 }
 
 static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,