On Fri 24-02-17 08:26:09, Minchan Kim wrote: [...] > >From 9efb87a873db67a9e6ebf44fdabf7d05fe4b4e21 Mon Sep 17 00:00:00 2001 > From: Minchan Kim <[email protected]> > Date: Fri, 4 Nov 2016 09:12:39 +0900 > Subject: [PATCH v2] 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()") > Cc: Michal Hocko <[email protected]> > Cc: Matthew Wilcox <[email protected]> > Cc: <[email protected]> > Signed-off-by: Minchan Kim <[email protected]>
Acked-by: Michal Hocko <[email protected]> Thanks for the chagelog update > --- > * from v1 > * add more detailed description with Fix tag - Michal > > mm/filemap.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 2ba46f410c7c..1944c631e3e6 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1008,9 +1008,12 @@ void page_endio(struct page *page, bool is_write, int > err) > unlock_page(page); > } else { > 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); > } > -- > 2.7.4 -- Michal Hocko SUSE Labs
