ANDROID: mm/filemap: Fix missing put_page() for speculative page fault

find_get_page() returns a page with increased refcount, assuming a page exists at the given index. Ensure this refcount is dropped on error. Bug: 253068137 Fixes: cd333a0 ("BACKPORT: FROMLIST: mm: implement speculative handling in filemap_fault()") Change-Id: Idc7b9e3f11f32a02bed4c6f4e11cec9200a5c790 Signed-off-by: Patrick Daly <[email protected]>
zainarbani · Oct 12, 2022 · 6232eec · 6232eec
1 parent 0555154
commit 6232eec
Showing 1 changed file with 7 additions and 2 deletions.
diff --git a/mm/filemap.c b/mm/filemap.c
@@ -3055,11 +3055,14 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 
 	if (vmf->flags & FAULT_FLAG_SPECULATIVE) {
 		page = find_get_page(mapping, offset);
-		if (unlikely(!page) || unlikely(PageReadahead(page)))
+		if (unlikely(!page))
 			return VM_FAULT_RETRY;
 
+		if (unlikely(PageReadahead(page)))
+			goto page_put;
+
 		if (!trylock_page(page))
-			return VM_FAULT_RETRY;
+			goto page_put;
 
 		if (unlikely(compound_head(page)->mapping != mapping))
 			goto page_unlock;
@@ -3091,6 +3094,8 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 		return VM_FAULT_LOCKED;
 page_unlock:
 		unlock_page(page);
+page_put:
+		put_page(page);
 		return VM_FAULT_RETRY;
 	}