[PATCH] mm: validate inode in mapping_set_error

[Minchan Kim]

The swap address_space doesn't have host. Thus, it makes kernel crash once
swap write meets error. Fix it.

[1] 735e4ae5ba28, vfs: track per-sb writeback errors and report them to syncfs
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 include/linux/pagemap.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 17ba0fe59290..9cf540447e73 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -55,7 +55,8 @@ static inline void mapping_set_error(struct address_space *mapping, int error)
 	__filemap_set_wb_err(mapping, error);
 
 	/* Record it in superblock */
-	errseq_set(&mapping->host->i_sb->s_wb_err, error);
+	if (mapping->host)
+		errseq_set(&mapping->host->i_sb->s_wb_err, error);
 
 	/* Record it in flags for now, for legacy callers */
 	if (error == -ENOSPC)
-- 
2.28.0.1011.ga647a8990f-goog