[PATCH] mm: shmem: fix uninitialized variable use in me_pagecache_clean()

From: Arnd Bergmann
Date: Fri Oct 22 2021 - 02:47:56 EST


From: Arnd Bergmann <arnd@xxxxxxxx>

It appears that the has_extra_refcount() is now in the wrong place:

mm/memory-failure.c:892:6: error: variable 'extra_pins' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (!mapping) {
^~~~~~~~
mm/memory-failure.c:915:32: note: uninitialized use occurs here
if (has_extra_refcount(ps, p, extra_pins))
^~~~~~~~~~
mm/memory-failure.c:892:2: note: remove the 'if' if its condition is always false
if (!mapping) {
^~~~~~~~~~~~~~~
mm/memory-failure.c:879:6: error: variable 'extra_pins' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (PageAnon(p)) {
^~~~~~~~~~~
mm/memory-failure.c:915:32: note: uninitialized use occurs here
if (has_extra_refcount(ps, p, extra_pins))
^~~~~~~~~~
mm/memory-failure.c:879:2: note: remove the 'if' if its condition is always false
if (PageAnon(p)) {
^~~~~~~~~~~~~~~~~~
mm/memory-failure.c:871:17: note: initialize the variable 'extra_pins' to silence this warning
bool extra_pins;
^
= 0

In both of those cases, we already set an error code and don't
need to override that one.

Fixes: d882a43a0011 ("mm: shmem: don't truncate page if memory failure happens")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
This is caused by a commit im -mm, so the commit ID is not stable.
If the fix is correct, I'd suggest folding it into the original
change
---
mm/memory-failure.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 3b04f0361a58..e8c38e27b753 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -909,12 +909,12 @@ static int me_pagecache_clean(struct page_state *ps, struct page *p)
* Open: to take i_rwsem or not for this? Right now we don't.
*/
ret = truncate_error_page(p, page_to_pfn(p), mapping);
-out:
- unlock_page(p);
-
if (has_extra_refcount(ps, p, extra_pins))
ret = MF_FAILED;

+out:
+ unlock_page(p);
+
return ret;
}

--
2.29.2