path: root/mm
diff options
authorMinchan Kim <>2017-02-24 14:59:59 -0800
committerLinus Torvalds <>2017-02-24 17:46:56 -0800
commitdd8416c47715cf324c9a16f13273f9fda87acfed (patch)
treecc5242e75522222820fc691368dc9357b20ae50c /mm
parent9a8b300f2f7812ebf4630b8b40499da38b38e882 (diff)
mm: do not access page->mapping directly on page_endio
With rw_page, page_endio is used for completing IO on a page and it propagates write error to the address space if the IO fails. The problem is it accesses page->mapping directly which might be okay for file-backed pages but it shouldn't for anonymous page. Otherwise, it can corrupt one of field from anon_vma under us and system goes panic randomly. swap_writepage bdev_writepage ops->rw_page I encountered the BUG during developing new zram feature and it was really hard to figure it out because it made random crash, somtime mmap_sem lockdep, sometime other places where places never related to zram/zsmalloc, and not reproducible with some configuration. When I consider how that bug is subtle and people do fast-swap test with brd, it's worth to add stable mark, I think. Fixes: dd6bd0d9c7db ("swap: use bdev_read_page() / bdev_write_page()") Signed-off-by: Minchan Kim <> Acked-by: Michal Hocko <> Cc: Matthew Wilcox <> Cc: <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm')
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 2ba46f4..1944c63 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1008,9 +1008,12 @@ void page_endio(struct page *page, bool is_write, int err)
} else {
if (err) {
+ struct address_space *mapping;
- if (page->mapping)
- mapping_set_error(page->mapping, err);
+ mapping = page_mapping(page);
+ if (mapping)
+ mapping_set_error(mapping, err);