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Commit e8604cb4 authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

cgroup: fix spurious lockdep warning in cgroup_exit() 



cgroup_exit() is called in fork and exit path. If it's called in the
failure path during fork, PF_EXITING isn't set, and then lockdep will
complain.

Fix this by removing cgroup_exit() in that failure path. cgroup_fork()
does nothing that needs cleanup.

Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 01a97140

kernel/cgroup.c

+1 −2
Original line number Diff line number Diff line
@@ -4431,8 +4431,7 @@ void cgroup_post_fork(struct task_struct *child) 
 * notify_on_release(), then leave the task attached to the root cgroup in

 * each hierarchy for the remainder of its exit.  No need to bother with

 * init_css_set refcnting.  init_css_set never goes away and we can't race

 * with migration path - either PF_EXITING is visible to migration path or

 * @tsk never got on the tasklist.

 * with migration path - PF_EXITING is visible to migration path.

 */

void cgroup_exit(struct task_struct *tsk, int run_callbacks)

{

kernel/fork.c

+2 −3
Original line number Diff line number Diff line
@@ -1271,7 +1271,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	if (IS_ERR(p->mempolicy)) {

		retval = PTR_ERR(p->mempolicy);

		p->mempolicy = NULL;

		goto bad_fork_cleanup_cgroup;

		goto bad_fork_cleanup_threadgroup_lock;

	}

	mpol_fix_fork_child_flag(p);

#endif
@@ -1524,11 +1524,10 @@ bad_fork_cleanup_policy: 
	perf_event_free_task(p);

#ifdef CONFIG_NUMA

	mpol_put(p->mempolicy);

bad_fork_cleanup_cgroup:

bad_fork_cleanup_threadgroup_lock:

#endif

	if (clone_flags & CLONE_THREAD)

		threadgroup_change_end(current);

	cgroup_exit(p, 0);

	delayacct_tsk_free(p);

	module_put(task_thread_info(p)->exec_domain->module);

bad_fork_cleanup_count: