diff options
| -rw-r--r-- | mm/filemap.c | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 3461d97ecb30..da7a35d83de7 100644 --- 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. |