Re: [PATCH 1/2] dax: Check page->mapping isn't NULL

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(a)vger.kernel.org Reported-by: Jan Kara <jack(a)suse.cz&gt; Signed-off-by: Matthew Wilcox <willy(a)infradead.org&gt;

--- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 9bcce89ea18e..e69fc231833b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -365,7 +365,7 @@ bool dax_lock_mapping_entry(struct page *page) struct address_space *mapping = READ_ONCE(page->mapping); locked = false; - if (!dax_mapping(mapping)) + if (!mapping || !dax_mapping(mapping)) break; /* -- 2.19.1