[PATCH] __unmap_hugepage_range(): add comment

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a088f593a807..f7355bf2f285 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -365,6 +365,11 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
         pte_t pte;
         struct page *page;
         struct page *tmp;
+        /*
+         * A page gathering list, protected by per file i_mmap_lock. The
+         * lock is used to avoid list corruption from multiple unmapping
+         * of the same page since we are using page->lru.
+         */
         LIST_HEAD(page_list);
 
         WARN_ON(!is_vm_hugetlb_page(vma));