This is a note to let you know that I've just added the patch titled
mm: do not access page->mapping directly on page_endio
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-do-not-access-page-mapping-directly-on-page_endio.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dd8416c47715cf324c9a16f13273f9fda87acfed Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@xxxxxxxxxx>
Date: Fri, 24 Feb 2017 14:59:59 -0800
Subject: mm: do not access page->mapping directly on page_endio
From: Minchan Kim <minchan@xxxxxxxxxx>
commit dd8416c47715cf324c9a16f13273f9fda87acfed upstream.
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 <minchan@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -865,9 +865,12 @@ void page_endio(struct page *page, int r
unlock_page(page);
} else { /* rw == WRITE */
if (err) {
+ struct address_space *mapping;
+
SetPageError(page);
- if (page->mapping)
- mapping_set_error(page->mapping, err);
+ mapping = page_mapping(page);
+ if (mapping)
+ mapping_set_error(mapping, err);
}
end_page_writeback(page);
}
Patches currently in stable-queue which might be from minchan@xxxxxxxxxx are
queue-4.4/mm-vmpressure-fix-sending-wrong-events-on-underflow.patch
queue-4.4/mm-do-not-access-page-mapping-directly-on-page_endio.patch