[PATCH AUTOSEL for 4.9 33/55] xfs: fortify xfs_alloc_buftarg error handling

[Sasha Levin]

From: Michal Hocko <mhocko@xxxxxxxx>

[ Upstream commit d210a9874b8f6166579408131cb74495caff1958 ]

percpu_counter_init failure path doesn't clean up &btp->bt_lru list.
Call list_lru_destroy in that error path. Similarly register_shrinker
error path is not handled.

While it is unlikely to trigger these error path, it is not impossible
especially the later might fail with large NUMAs.  Let's handle the
failure to make the code more robust.

Noticed-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 fs/xfs/xfs_buf.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index eca7baecc9f0..3f45d9867e10 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1785,22 +1785,27 @@ xfs_alloc_buftarg(
 	btp->bt_bdi = blk_get_backing_dev_info(bdev);
 
 	if (xfs_setsize_buftarg_early(btp, bdev))
-		goto error;
+		goto error_free;
 
 	if (list_lru_init(&btp->bt_lru))
-		goto error;
+		goto error_free;
 
 	if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
-		goto error;
+		goto error_lru;
 
 	btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
 	btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
 	btp->bt_shrinker.seeks = DEFAULT_SEEKS;
 	btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
-	register_shrinker(&btp->bt_shrinker);
+	if (register_shrinker(&btp->bt_shrinker))
+		goto error_pcpu;
 	return btp;
 
-error:
+error_pcpu:
+	percpu_counter_destroy(&btp->bt_io_count);
+error_lru:
+	list_lru_destroy(&btp->bt_lru);
+error_free:
 	kmem_free(btp);
 	return NULL;
 }
-- 
2.11.0