| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 134/142] dax: Check page->mapping isnt NULL | Date | Fri, 14 Dec 2018 13:00:19 +0100 |
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4.19-stable review patch. If anyone has any objections, please let me know.
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From: Matthew Wilcox <willy@infradead.org>
commit c93db7bb6ef3251e0ea48ade311d3e9942748e1c upstream.
If we race with inode destroy, it's possible for page->mapping to be NULL before we even enter this routine, as well as after having slept waiting for the dax entry to become unlocked.
Fixes: c2a7d2a11552 ("filesystem-dax: Introduce dax_lock_mapping_entry()") Cc: <stable@vger.kernel.org> Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/dax.c +++ b/fs/dax.c @@ -423,7 +423,7 @@ bool dax_lock_mapping_entry(struct page for (;;) { mapping = READ_ONCE(page->mapping); - if (!dax_mapping(mapping)) + if (!mapping || !dax_mapping(mapping)) break; /*
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