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Commit 748e7fc2 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-4.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fixes from Tejun Heo:
 "Two fixes for cgroup.

   - There still was a hole in enforcing cpuset rules, fixed by Li.

   - The recent switch to global percpu_rwseom for threadgroup locking
     revealed a couple issues in how percpu_rwsem is implemented and
     used by cgroup.  Balbir found that the read locking section was too
     wide unnecessarily including operations which can often depend on
     IOs.  With percpu_rwsem updates (coming through a different tree)
     and reduction of read locking section, all the reported locking
     latency issues, including the android one, are resolved.

  It looks like we can keep global percpu_rwsem locking for now.  If
  there actually are cases which can't be resolved, we can go back to
  more complex per-signal_struct locking"

* 'for-4.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: reduce read locked section of cgroup_threadgroup_rwsem during fork
  cpuset: make sure new tasks conform to the current config of the cpuset
parents e4e98c46 568ac888

kernel/cpuset.c

+15 −0
Original line number Diff line number Diff line
@@ -2069,6 +2069,20 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css) 
	mutex_unlock(&cpuset_mutex);

}



/*

 * Make sure the new task conform to the current state of its parent,

 * which could have been changed by cpuset just after it inherits the

 * state from the parent and before it sits on the cgroup's task list.

 */

void cpuset_fork(struct task_struct *task)

{

	if (task_css_is_root(task, cpuset_cgrp_id))

		return;



	set_cpus_allowed_ptr(task, &current->cpus_allowed);

	task->mems_allowed = current->mems_allowed;

}



struct cgroup_subsys cpuset_cgrp_subsys = {

	.css_alloc	= cpuset_css_alloc,

	.css_online	= cpuset_css_online,
@@ -2079,6 +2093,7 @@ struct cgroup_subsys cpuset_cgrp_subsys = { 
	.attach		= cpuset_attach,

	.post_attach	= cpuset_post_attach,

	.bind		= cpuset_bind,

	.fork		= cpuset_fork,

	.legacy_cftypes	= files,

	.early_init	= true,

};

kernel/fork.c

+2 −2
Original line number Diff line number Diff line
@@ -1404,7 +1404,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	p->real_start_time = ktime_get_boot_ns();

	p->io_context = NULL;

	p->audit_context = NULL;

	threadgroup_change_begin(current);

	cgroup_fork(p);

#ifdef CONFIG_NUMA

	p->mempolicy = mpol_dup(p->mempolicy);
@@ -1556,6 +1555,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	INIT_LIST_HEAD(&p->thread_group);

	p->task_works = NULL;



	threadgroup_change_begin(current);

	/*

	 * Ensure that the cgroup subsystem policies allow the new process to be

	 * forked. It should be noted the the new process's css_set can be changed
@@ -1656,6 +1656,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
bad_fork_cancel_cgroup:

	cgroup_cancel_fork(p);

bad_fork_free_pid:

	threadgroup_change_end(current);

	if (pid != &init_struct_pid)

		free_pid(pid);

bad_fork_cleanup_thread:
@@ -1688,7 +1689,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	mpol_put(p->mempolicy);

bad_fork_cleanup_threadgroup_lock:

#endif

	threadgroup_change_end(current);

	delayacct_tsk_free(p);

bad_fork_cleanup_count:

	atomic_dec(&p->cred->user->processes);