linux-kernel - [PATCH 4.4 006/168] mm: mempolicy: make mbind() return -EIO when MPOL_MF

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Date:   Wed, 24 Apr 2019 19:07:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Yang Shi <yang.shi@...ux.alibaba.com>,
        Oscar Salvador <osalvador@...e.de>,
        Cyril Hrubis <chrubis@...e.cz>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Rafael Aquini <aquini@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.4 006/168] mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified

From: Yang Shi <yang.shi@...ux.alibaba.com>

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@...ux-foundation.org: tweak code comment]
Link: http://lkml.kernel.org/r/1553020556-38583-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: 6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>
Signed-off-by: Oscar Salvador <osalvador@...e.de>
Reported-by: Cyril Hrubis <chrubis@...e.cz>
Suggested-by: Kirill A. Shutemov <kirill@...temov.name>
Acked-by: Rafael Aquini <aquini@...hat.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
Acked-by: David Rientjes <rientjes@...gle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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,