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-rw-r--r--mm/filemap.c25
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.