1 files changed, 30 insertions, 33 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index d2e6a79fe69d..8426434042f4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -152,25 +152,25 @@ static void filemap_unaccount_folio(struct address_space *mapping,
 
 	VM_BUG_ON_FOLIO(folio_mapped(folio), folio);
 	if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(folio_mapped(folio))) {
-		int mapcount;
-
 		pr_alert("BUG: Bad page cache in process %s  pfn:%05lx\n",
 			 current->comm, folio_pfn(folio));
 		dump_page(&folio->page, "still mapped when deleted");
 		dump_stack();
 		add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 
-		mapcount = page_mapcount(&folio->page);
-		if (mapping_exiting(mapping) &&
-		    folio_ref_count(folio) >= mapcount + 2) {
-			/*
-			 * All vmas have already been torn down, so it's
-			 * a good bet that actually the folio 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(&folio->page);
-			folio_ref_sub(folio, mapcount);
+		if (mapping_exiting(mapping) && !folio_test_large(folio)) {
+			int mapcount = page_mapcount(&folio->page);
+
+			if (folio_ref_count(folio) >= mapcount + 2) {
+				/*
+				 * All vmas have already been torn down, so it's
+				 * a good bet that actually the page is unmapped
+				 * and we'd rather not leak it: if we're wrong,
+				 * another bad page check should catch it later.
+				 */
+				page_mapcount_reset(&folio->page);
+				folio_ref_sub(folio, mapcount);
+			}
 		}
 	}
 
@@ -193,16 +193,20 @@ static void filemap_unaccount_folio(struct address_space *mapping,
 	/*
 	 * At this point folio must be either written or cleaned by
 	 * truncate.  Dirty folio here signals a bug and loss of
-	 * unwritten data.
+	 * unwritten data - on ordinary filesystems.
+	 *
+	 * But it's harmless on in-memory filesystems like tmpfs; and can
+	 * occur when a driver which did get_user_pages() sets page dirty
+	 * before putting it, while the inode is being finally evicted.
 	 *
-	 * This fixes dirty accounting after removing the folio entirely
+	 * Below fixes dirty accounting after removing the folio entirely
 	 * but leaves the dirty flag set: it has no effect for truncated
 	 * folio and anyway will be cleared before returning folio to
 	 * buddy allocator.
 	 */
-	if (WARN_ON_ONCE(folio_test_dirty(folio)))
-		folio_account_cleaned(folio, mapping,
-					inode_to_wb(mapping->host));
+	if (WARN_ON_ONCE(folio_test_dirty(folio) &&
+			 mapping_can_writeback(mapping)))
+		folio_account_cleaned(folio, inode_to_wb(mapping->host));
 }
 
 /*
@@ -1185,24 +1189,17 @@ static void folio_wake_bit(struct folio *folio, int bit_nr)
 	}
 
 	/*
-	 * It is possible for other pages to have collided on the waitqueue
-	 * hash, so in that case check for a page match. That prevents a long-
-	 * term waiter
+	 * It's possible to miss clearing waiters here, when we woke our page
+	 * waiters, but the hashed waitqueue has waiters for other pages on it.
+	 * That's okay, it's a rare case. The next waker will clear it.
 	 *
-	 * It is still possible to miss a case here, when we woke page waiters
-	 * and removed them from the waitqueue, but there are still other
-	 * page waiters.
+	 * Note that, depending on the page pool (buddy, hugetlb, ZONE_DEVICE,
+	 * other), the flag may be cleared in the course of freeing the page;
+	 * but that is not required for correctness.
 	 */
-	if (!waitqueue_active(q) || !key.page_match) {
+	if (!waitqueue_active(q) || !key.page_match)
 		folio_clear_waiters(folio);
-		/*
-		 * It's possible to miss clearing Waiters here, when we woke
-		 * our page waiters, but the hashed waitqueue has waiters for
-		 * other pages on it.
-		 *
-		 * That's okay, it's a rare case. The next waker will clear it.
-		 */
-	}
+
 	spin_unlock_irqrestore(&q->lock, flags);
 }