Merge tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

[deliverable/linux.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 3461d97ecb30bfe18d1ed50729e5147aa2ad7e6d..da7a35d83de7edc4ed562caa5e1925194f2c7229 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -195,6 +195,30 @@ void __delete_from_page_cache(struct page *page, void *shadow,
        else
                cleancache_invalidate_page(mapping, page);
 
+       VM_BUG_ON_PAGE(page_mapped(page), page);
+       if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(page_mapped(page))) {
+               int mapcount;
+
+               pr_alert("BUG: Bad page cache in process %s  pfn:%05lx\n",
+                        current->comm, page_to_pfn(page));
+               dump_page(page, "still mapped when deleted");
+               dump_stack();
+               add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+
+               mapcount = page_mapcount(page);
+               if (mapping_exiting(mapping) &&
+                   page_count(page) >= mapcount + 2) {
+                       /*
+                        * All vmas have already been torn down, so it's
+                        * a good bet that actually the page is unmapped,
+                        * and we'd prefer not to leak it: if we're wrong,
+                        * some other bad page check should catch it later.
+                        */
+                       page_mapcount_reset(page);
+                       atomic_sub(mapcount, &page->_count);
+               }
+       }
+
        page_cache_tree_delete(mapping, page, shadow);
 
        page->mapping = NULL;
@@ -205,7 +229,6 @@ void __delete_from_page_cache(struct page *page, void *shadow,
                __dec_zone_page_state(page, NR_FILE_PAGES);
        if (PageSwapBacked(page))
                __dec_zone_page_state(page, NR_SHMEM);
-       VM_BUG_ON_PAGE(page_mapped(page), page);
 
        /*
         * At this point page must be either written or cleaned by truncate.