mm: thp: split_huge_pmd_address() comment improvement

Comment is partly wrong, this improves it by including the case of
split_huge_pmd_address() called by try_to_unmap_one if TTU_SPLIT_HUGE_PMD
is set.

Link: http://lkml.kernel.org/r/1462547040-1737-4-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 86eafd9..1764184 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3023,8 +3023,10 @@ void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
                return;
 
        /*
-        * Caller holds the mmap_sem write mode, so a huge pmd cannot
-        * materialize from under us.
+        * Caller holds the mmap_sem write mode or the anon_vma lock,
+        * so a huge pmd cannot materialize from under us (khugepaged
+        * holds both the mmap_sem write mode and the anon_vma lock
+        * write mode).
         */
        __split_huge_pmd(vma, pmd, address, freeze);
 }