linux-kernel - [PATCH 4.9 07/91] mm: mempolicy: make mbind() return -EIO when MPOL_MF

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Date:   Thu,  4 Apr 2019 10:46:51 +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 4.9 07/91] mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

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 |   18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -547,11 +547,16 @@ retry:
 			goto retry;
 		}

-		migrate_page_add(page, qp->pagelist, flags);
+		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,
@@ -623,7 +628,12 @@ static int queue_pages_test_walk(unsigne
 	unsigned long endvma = vma->vm_end;
 	unsigned long flags = qp->flags;

-	if (!vma_migratable(vma))
+	/*
+	 * Need check MPOL_MF_STRICT to return -EIO if possible
+	 * regardless of vma_migratable
+	 */
+	if (!vma_migratable(vma) &&
+	    !(flags & MPOL_MF_STRICT))
 		return 1;

 	if (endvma > end)
@@ -650,7 +660,7 @@ static int queue_pages_test_walk(unsigne
 	}

 	/* queue pages from current vma */
-	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+	if (flags & MPOL_MF_VALID)
 		return 0;
 	return 1;
 }