filemap: update offset check in filemap_fault()

With THP, current check of offset:

    VM_BUG_ON_PAGE(page->index != offset, page);

is no longer accurate. Update it to:

    VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);

Link: http://lkml.kernel.org/r/20190801184244.3169074-4-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index 0b30110..f4d2971 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2545,7 +2545,7 @@ retry_find:
                put_page(page);
                goto retry_find;
        }
-       VM_BUG_ON_PAGE(page->index != offset, page);
+       VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
 
        /*
         * We have a locked page in the page cache, now we need to check