linux-kernel - [PATCH 3.4 001/107] Btrfs: use kmem_cache_free when freeing entry in inode cache

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Date:	Wed, 16 Mar 2016 16:04:55 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Filipe Manana <fdmanana@...e.com>,
	Chris Mason <clm@...com>, Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 001/107] Btrfs: use kmem_cache_free when freeing entry in inode cache

From: Filipe Manana <fdmanana@...e.com>

3.4.111-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit c3f4a1685bb87e59c886ee68f7967eae07d4dffa upstream.

The free space entries are allocated using kmem_cache_zalloc(),
through __btrfs_add_free_space(), therefore we should use
kmem_cache_free() and not kfree() to avoid any confusion and
any potential problem. Looking at the kfree() definition at
mm/slab.c it has the following comment:

  /*
   * (...)
   *
   * Don't free memory not originally allocated by kmalloc()
   * or you will run into trouble.
   */

So better be safe and use kmem_cache_free().

Signed-off-by: Filipe Manana <fdmanana@...e.com>
Reviewed-by: David Sterba <dsterba@...e.cz>
Signed-off-by: Chris Mason <clm@...com>
Signed-off-by: Zefan Li <lizefan@...wei.com>
---
 fs/btrfs/inode-map.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index b1a1c92..47abfd2 100644
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -283,7 +283,7 @@ void btrfs_unpin_free_ino(struct btrfs_root *root)
 		__btrfs_add_free_space(ctl, info->offset, count);
 free:
 		rb_erase(&info->offset_index, rbroot);
-		kfree(info);
+		kmem_cache_free(btrfs_free_space_cachep, info);
 	}
 }
 
-- 
1.9.1