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

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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
This commit is contained in:
Linus Torvalds 2013-11-29 09:47:06 -08:00
commit 2855987d13
2 changed files with 37 additions and 6 deletions
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35
kernel/cgroup.c
View File

@ -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 @@ out:
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

8
kernel/cpuset.c
View File

@ -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);
}