Re: [PATCH] sysfs: fix namespace refcnt leak
From: Tejun Heo <tj@kernel.org>
Date: 2014-02-18 23:12:49
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Hey, On Mon, Feb 17, 2014 at 11:54:59AM +0800, Li Zefan wrote:
I think we have to fix kernfs in order to fix refcnt leak in sysfs and cgroupfs. This fix is for 3.14, but it creates conflicts for cgroup-next. ==================== As mount() and kill_sb() is not a one-to-one match, we shoudn't get ns refcnt unconditionally in sysfs_mount(), and instead we should get the refcnt only when kernfs_mount() allocated a new superblock.
Ugh... nasty :(
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@@ -132,6 +132,7 @@ const void *kernfs_super_ns(struct super_block *sb) * @flags: mount flags specified for the mount * @root: kernfs_root of the hierarchy being mounted * @ns: optional namespace tag of the mount + * @new: tell the caller if we allocated a new superblock
Maybe something like @new_sb_created is better?
struct super_block *sb; struct kernfs_super_info *info; int error; + *new_sb = false;
Can we make it optional so that users who don't care about it can ignore it?
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@@ -430,9 +431,9 @@ static inline int kernfs_rename(struct kernfs_node *kn, static inline struct dentry * kernfs_mount(struct file_system_type *fs_type, int flags, - struct kernfs_root *root) + struct kernfs_root *root, bool *new_sb) { - return kernfs_mount_ns(fs_type, flags, root, NULL); + return kernfs_mount_ns(fs_type, flags, root, NULL, new_sb);
And let kernfs_mount() just use NULL for the parameter? Thanks. -- tejun