diff options
| author | Li Zefan <lizf@cn.fujitsu.com> | 2009-01-29 14:25:21 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-29 18:04:45 -0800 |
| commit | 1404f06565ee89e0ce04d4a5859c00b0e3a0dc8d (patch) | |
| tree | e2f294ed420461e0032e03143f06634b883dc06e | |
| parent | 945048ca36173315afa2f0c53bed21ba01a588c1 (diff) | |
| download | lwn-1404f06565ee89e0ce04d4a5859c00b0e3a0dc8d.tar.gz lwn-1404f06565ee89e0ce04d4a5859c00b0e3a0dc8d.zip | |
cgroups: fix lock inconsistency in cgroup_clone()
I fixed a bug in cgroup_clone() in Linus' tree in commit 7b574b7
("cgroups: fix a race between cgroup_clone and umount") without noticing
there was a cleanup patch in -mm tree that should be rebased (now commit
104cbd5, "cgroups: use task_lock() for access tsk->cgroups safe in
cgroup_clone()"), thus resulted in lock inconsistency.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/cgroup.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2ae7cb47dbfa..0066092de19a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2993,20 +2993,21 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, mutex_unlock(&cgroup_mutex); return 0; } - task_lock(tsk); - cg = tsk->cgroups; - parent = task_cgroup(tsk, subsys->subsys_id); /* Pin the hierarchy */ - if (!atomic_inc_not_zero(&parent->root->sb->s_active)) { + if (!atomic_inc_not_zero(&root->sb->s_active)) { /* We race with the final deactivate_super() */ mutex_unlock(&cgroup_mutex); return 0; } /* Keep the cgroup alive */ + task_lock(tsk); + parent = task_cgroup(tsk, subsys->subsys_id); + cg = tsk->cgroups; get_css_set(cg); task_unlock(tsk); + mutex_unlock(&cgroup_mutex); /* Now do the VFS work to create a cgroup */ @@ -3045,7 +3046,7 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, mutex_unlock(&inode->i_mutex); put_css_set(cg); - deactivate_super(parent->root->sb); + deactivate_super(root->sb); /* The cgroup is still accessible in the VFS, but * we're not going to try to rmdir() it at this * point. */ @@ -3071,7 +3072,7 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, mutex_lock(&cgroup_mutex); put_css_set(cg); mutex_unlock(&cgroup_mutex); - deactivate_super(parent->root->sb); + deactivate_super(root->sb); return ret; } |