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Commit 2855987d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fixes from Tejun Heo:
 "Fixes for three issues.

   - cgroup destruction path could swamp system_wq possibly leading to
     deadlock.  This actually seems to happen in the wild with memcg
     because memcg destruction path adds nested dependency on system_wq.

     Resolved by isolating cgroup destruction work items on its
     dedicated workqueue.

   - Possible locking context deadlock through seqcount reported by
     lockdep

   - Memory leak under certain conditions"

* 'for-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: fix cgroup_subsys_state leak for seq_files
  cpuset: Fix memory allocator deadlock
  cgroup: use a dedicated workqueue for cgroup destruction
parents b8495995 e605b365

kernel/cgroup.c

+31 −4
Original line number Diff line number Diff line
@@ -89,6 +89,14 @@ static DEFINE_MUTEX(cgroup_mutex); 


static DEFINE_MUTEX(cgroup_root_mutex);



/*

 * cgroup destruction makes heavy use of work items and there can be a lot

 * of concurrent destructions.  Use a separate workqueue so that cgroup

 * destruction work items don't end up filling up max_active of system_wq

 * which may lead to deadlock.

 */

static struct workqueue_struct *cgroup_destroy_wq;



/*

 * Generate an array of cgroup subsystem pointers. At boot time, this is

 * populated with the built in subsystems, and modular subsystems are
@@ -191,6 +199,7 @@ static void cgroup_destroy_css_killed(struct cgroup *cgrp); 
static int cgroup_destroy_locked(struct cgroup *cgrp);

static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],

			      bool is_add);

static int cgroup_file_release(struct inode *inode, struct file *file);



/**

 * cgroup_css - obtain a cgroup's css for the specified subsystem
@@ -871,7 +880,7 @@ static void cgroup_free_rcu(struct rcu_head *head) 
	struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head);



	INIT_WORK(&cgrp->destroy_work, cgroup_free_fn);

	schedule_work(&cgrp->destroy_work);

	queue_work(cgroup_destroy_wq, &cgrp->destroy_work);

}



static void cgroup_diput(struct dentry *dentry, struct inode *inode)
@@ -2421,7 +2430,7 @@ static const struct file_operations cgroup_seqfile_operations = { 
	.read = seq_read,

	.write = cgroup_file_write,

	.llseek = seq_lseek,

	.release = single_release,

	.release = cgroup_file_release,

};



static int cgroup_file_open(struct inode *inode, struct file *file)
@@ -2482,6 +2491,8 @@ static int cgroup_file_release(struct inode *inode, struct file *file) 
		ret = cft->release(inode, file);

	if (css->ss)

		css_put(css);

	if (file->f_op == &cgroup_seqfile_operations)

		single_release(inode, file);

	return ret;

}
@@ -4249,7 +4260,7 @@ static void css_free_rcu_fn(struct rcu_head *rcu_head) 
	 * css_put().  dput() requires process context which we don't have.

	 */

	INIT_WORK(&css->destroy_work, css_free_work_fn);

	schedule_work(&css->destroy_work);

	queue_work(cgroup_destroy_wq, &css->destroy_work);

}



static void css_release(struct percpu_ref *ref)
@@ -4539,7 +4550,7 @@ static void css_killed_ref_fn(struct percpu_ref *ref) 
		container_of(ref, struct cgroup_subsys_state, refcnt);



	INIT_WORK(&css->destroy_work, css_killed_work_fn);

	schedule_work(&css->destroy_work);

	queue_work(cgroup_destroy_wq, &css->destroy_work);

}



/**
@@ -5063,6 +5074,22 @@ int __init cgroup_init(void) 
	return err;

}



static int __init cgroup_wq_init(void)

{

	/*

	 * There isn't much point in executing destruction path in

	 * parallel.  Good chunk is serialized with cgroup_mutex anyway.

	 * Use 1 for @max_active.

	 *

	 * We would prefer to do this in cgroup_init() above, but that

	 * is called before init_workqueues(): so leave this until after.

	 */

	cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);

	BUG_ON(!cgroup_destroy_wq);

	return 0;

}

core_initcall(cgroup_wq_init);



/*

 * proc_cgroup_show()

 *  - Print task's cgroup paths into seq_file, one line for each hierarchy

kernel/cpuset.c

+6 −2
Original line number Diff line number Diff line
@@ -1033,8 +1033,10 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk, 
	need_loop = task_has_mempolicy(tsk) ||

			!nodes_intersects(*newmems, tsk->mems_allowed);



	if (need_loop)

	if (need_loop) {

		local_irq_disable();

		write_seqcount_begin(&tsk->mems_allowed_seq);

	}



	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);

	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
@@ -1042,8 +1044,10 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk, 
	mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);

	tsk->mems_allowed = *newmems;



	if (need_loop)

	if (need_loop) {

		write_seqcount_end(&tsk->mems_allowed_seq);

		local_irq_enable();

	}



	task_unlock(tsk);

}