[PATCH] mbcache: fix to detect failure of register_shrinker

From: Chao Yu <redacted>

register_shrinker in mb_cache_create may fail due to no memory. This
patch fixes to do the check of return value of register_shrinker and
handle the error case, otherwise mb_cache_create may return with no
error, but losing the inner shrinker.

Signed-off-by: Chao Yu <redacted>
---
 fs/mbcache.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/mbcache.c b/fs/mbcache.c
index eccda3a..c5bd19f 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c

@@ -366,7 +366,11 @@ struct mb_cache *mb_cache_create(int bucket_bits)
 	cache->c_shrink.count_objects = mb_cache_count;
 	cache->c_shrink.scan_objects = mb_cache_scan;
 	cache->c_shrink.seeks = DEFAULT_SEEKS;
-	register_shrinker(&cache->c_shrink);
+	if (register_shrinker(&cache->c_shrink)) {
+		kfree(cache->c_hash);
+		kfree(cache);
+		goto err_out;
+	}
 
 	INIT_WORK(&cache->c_shrink_work, mb_cache_shrink_worker);
 

-- 
2.7.2

On Mon 16-05-16 23:16:38, Chao Yu wrote:

From: Chao Yu <redacted>

register_shrinker in mb_cache_create may fail due to no memory. This
patch fixes to do the check of return value of register_shrinker and
handle the error case, otherwise mb_cache_create may return with no
error, but losing the inner shrinker.

Signed-off-by: Chao Yu <redacted>

Thanks for fixing this. The patch looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

-- 
Jan Kara [off-list ref]
SUSE Labs, CR

On Mon, May 16, 2016 at 11:16:38PM +0800, Chao Yu wrote:

From: Chao Yu <redacted>

register_shrinker in mb_cache_create may fail due to no memory. This
patch fixes to do the check of return value of register_shrinker and
handle the error case, otherwise mb_cache_create may return with no
error, but losing the inner shrinker.

Signed-off-by: Chao Yu <redacted>
Reviewed-by: Jan Kara <jack@suse.cz>

Applied, thanks.  (Apologies for the delay; this patch slipped through
the cracks.)

					- Ted

On 2016/7/6 4:16, Theodore Ts'o wrote:

On Mon, May 16, 2016 at 11:16:38PM +0800, Chao Yu wrote:

quoted

From: Chao Yu <redacted>

register_shrinker in mb_cache_create may fail due to no memory. This
patch fixes to do the check of return value of register_shrinker and
handle the error case, otherwise mb_cache_create may return with no
error, but losing the inner shrinker.

Signed-off-by: Chao Yu <redacted>
Reviewed-by: Jan Kara <jack@suse.cz>

Applied, thanks.  (Apologies for the delay; this patch slipped through
the cracks.)

Ping, didn't see it in mainline, is this patch still under testing now?

					- Ted

On Wed, Aug 31, 2016 at 11:31:17PM +0800, Chao Yu wrote:

On 2016/7/6 4:16, Theodore Ts'o wrote:

quoted

On Mon, May 16, 2016 at 11:16:38PM +0800, Chao Yu wrote:

quoted

From: Chao Yu <redacted>

register_shrinker in mb_cache_create may fail due to no memory. This
patch fixes to do the check of return value of register_shrinker and
handle the error case, otherwise mb_cache_create may return with no
error, but losing the inner shrinker.

Signed-off-by: Chao Yu <redacted>
Reviewed-by: Jan Kara <jack@suse.cz>

Applied, thanks.  (Apologies for the delay; this patch slipped through
the cracks.)

Ping, didn't see it in mainline, is this patch still under testing now?

I'm sorry, I'm not sure how it got dropped, but it's not in mainline
and I'm not sure how it got dropped from the ext4 tree.

It's now queued up in the dev tree.

Thanks for checking back,

						- Ted

On 2016/8/31 23:48, Theodore Ts'o wrote:

On Wed, Aug 31, 2016 at 11:31:17PM +0800, Chao Yu wrote:

quoted

On 2016/7/6 4:16, Theodore Ts'o wrote:

quoted

On Mon, May 16, 2016 at 11:16:38PM +0800, Chao Yu wrote:

quoted

From: Chao Yu <redacted>

register_shrinker in mb_cache_create may fail due to no memory. This
patch fixes to do the check of return value of register_shrinker and
handle the error case, otherwise mb_cache_create may return with no
error, but losing the inner shrinker.

Signed-off-by: Chao Yu <redacted>
Reviewed-by: Jan Kara <jack@suse.cz>

Applied, thanks.  (Apologies for the delay; this patch slipped through
the cracks.)

Ping, didn't see it in mainline, is this patch still under testing now?

I'm sorry, I'm not sure how it got dropped, but it's not in mainline
and I'm not sure how it got dropped from the ext4 tree.

It's now queued up in the dev tree.

Thanks for checking back,

Thanks for merging! ;)

						- Ted