mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY

MPOL_MF_LAZY is not visible from userspace since a720094ded8c ("mm:
mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now"), but
it should still skip non-migratable VMAs such as VM_IO, VM_PFNMAP, and
VM_HUGETLB VMAs, and avoid useless overhead of minor faults.

Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Signed-off-by: Gavin Guo <gavin.guo@canonical.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 973434e..27d1354 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -644,7 +644,8 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
 
        if (flags & MPOL_MF_LAZY) {
                /* Similar to task_numa_work, skip inaccessible VMAs */
-               if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
+               if (vma_migratable(vma) &&
+                       vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
                        change_prot_numa(vma, start, endvma);
                return 1;
        }