diff --git a/mm/rmap.c b/mm/rmap.c index 09b08888120e115e0bc2a4680dea78ca24e223ef..66cb69c1c5dde0ed17e8a9f9b74f846b2bed2d19 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1252,6 +1252,17 @@ void page_add_file_rmap(struct page *page, bool compound) } if (!atomic_inc_and_test(compound_mapcount_ptr(page))) goto out; + + /* + * It is racy to ClearPageDoubleMap in page_remove_file_rmap(); + * but page lock is held by all page_add_file_rmap() compound + * callers, and SetPageDoubleMap below warns if !PageLocked: + * so here is a place that DoubleMap can be safely cleared. + */ + VM_WARN_ON_ONCE(!PageLocked(page)); + if (nr == nr_pages && PageDoubleMap(page)) + ClearPageDoubleMap(page); + if (PageSwapBacked(page)) __mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED, nr_pages);