[BUGFIX] cgroup: create a workqueue for cgroup
From: Daisuke Nishimura
Date: Fri Sep 30 2011 - 04:00:14 EST
In commit:f90d4118, cpuset_wq, a separate workqueue for cpuset, was introduced
to avoid a dead lock against cgroup_mutex between async_rebuild_sched_domains()
and cgroup_tasks_write().
But check_for_release() has a similar problem:
check_for_release()
schedule_work(release_agent_work)
cgroup_release_agent()
mutex_lock(&cgroup_mutex)
And I actually see a lockup which seems to be caused by this problem
on 2.6.32-131.0.15.el6.x86_64.
[59161.355412] INFO: task events/2:37 blocked for more than 120 seconds.
[59161.358404] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59161.361472] events/2 D 0000000000000002 0 37 2 0x00000000
[59161.364460] ffff88007db51d10 0000000000000046 0000000000000086 0000000000000003
[59161.377729] 0000000000000001 000000004da0228a ffff88007db51cc0 7fffffffffffffff
[59161.390090] ffff88007db4a6b8 ffff88007db51fd8 000000000000f598 ffff88007db4a6b8
[59161.413749] Call Trace:
[59161.415084] [<ffffffff814dc84e>] __mutex_lock_slowpath+0x13e/0x180
[59161.417861] [<ffffffff814dc6eb>] mutex_lock+0x2b/0x50
[59161.420013] [<ffffffff810bcfb1>] cgroup_release_agent+0x101/0x240
[59161.422701] [<ffffffff8108e44e>] ? prepare_to_wait+0x4e/0x80
[59161.425164] [<ffffffff810bceb0>] ? cgroup_release_agent+0x0/0x240
[59161.427878] [<ffffffff81088830>] worker_thread+0x170/0x2a0
[59161.430428] [<ffffffff8108e160>] ? autoremove_wake_function+0x0/0x40
[59161.435173] [<ffffffff810886c0>] ? worker_thread+0x0/0x2a0
[59161.439267] [<ffffffff8108ddf6>] kthread+0x96/0xa0
[59161.441864] [<ffffffff8100c1ca>] child_rip+0xa/0x20
[59161.444076] [<ffffffff8108dd60>] ? kthread+0x0/0xa0
[59161.448333] [<ffffffff8100c1c0>] ? child_rip+0x0/0x20
...
[59161.728561] INFO: task move_task:14311 blocked for more than 120 seconds.
[59161.733614] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59161.740374] move_task D 0000000000000000 0 14311 7337 0x00000080
[59161.749131] ffff8800c8bbf968 0000000000000082 0000000000000000 ffff8800c8bbf92c
[59161.758975] ffff8800c8bbf8e8 ffff88007fc24100 ffff880028315f80 00000001037f9572
[59161.764257] ffff8800c8868678 ffff8800c8bbffd8 000000000000f598 ffff8800c8868678
[59161.773686] Call Trace:
[59161.775375] [<ffffffff814dc065>] schedule_timeout+0x215/0x2e0
[59161.781194] [<ffffffff814dbce3>] wait_for_common+0x123/0x180
[59161.786500] [<ffffffff8105dc60>] ? default_wake_function+0x0/0x20
[59161.791399] [<ffffffff81124180>] ? lru_add_drain_per_cpu+0x0/0x10
[59161.798017] [<ffffffff814dbdfd>] wait_for_completion+0x1d/0x20
[59161.801644] [<ffffffff81089227>] flush_work+0x77/0xc0
[59161.816983] [<ffffffff81088cb0>] ? wq_barrier_func+0x0/0x20
[59161.819407] [<ffffffff810893a3>] schedule_on_each_cpu+0x133/0x180
[59161.822816] [<ffffffff81123855>] lru_add_drain_all+0x15/0x20
[59161.825066] [<ffffffff8115f6fe>] migrate_prep+0xe/0x20
[59161.827263] [<ffffffff8115252b>] do_migrate_pages+0x2b/0x210
[59161.829802] [<ffffffff81151f45>] ? mpol_rebind_task+0x15/0x20
[59161.832249] [<ffffffff810bfcab>] ? cpuset_change_task_nodemask+0xdb/0x160
[59161.835240] [<ffffffff810c1198>] cpuset_migrate_mm+0x78/0xa0
[59161.838663] [<ffffffff810c25e7>] cpuset_attach+0x197/0x1d0
[59161.844383] [<ffffffff810be87e>] cgroup_attach_task+0x21e/0x660
[59161.849009] [<ffffffff810be520>] ? cgroup_file_open+0x0/0x140
[59161.854371] [<ffffffff8116fbcf>] ? __dentry_open+0x23f/0x360
[59161.857754] [<ffffffff814dc6de>] ? mutex_lock+0x1e/0x50
[59161.863157] [<ffffffff810bf00c>] cgroup_tasks_write+0x5c/0xf0
[59161.868148] [<ffffffff810bc01a>] cgroup_file_write+0x2ba/0x320
[59161.873288] [<ffffffff811910b0>] ? mntput_no_expire+0x30/0x110
[59161.876954] [<ffffffff81172718>] vfs_write+0xb8/0x1a0
[59161.881499] [<ffffffff810d1b62>] ? audit_syscall_entry+0x272/0x2a0
[59161.890183] [<ffffffff81173151>] sys_write+0x51/0x90
[59161.893340] [<ffffffff8100b172>] system_call_fastpath+0x16/0x1b
This patch fixes this problem by creating cgroup_wq, and making both
async_rebuild_domains() and check_for_release() use it.
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
---
include/linux/cgroup.h | 3 +++
init/main.c | 1 +
kernel/cgroup.c | 21 ++++++++++++++++++++-
kernel/cpuset.c | 13 +------------
4 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index da7e4bc..87bf979 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -27,6 +27,8 @@ struct css_id;
extern int cgroup_init_early(void);
extern int cgroup_init(void);
+extern void cgroup_wq_init(void);
+extern void queue_cgroup_work(struct work_struct *work);
extern void cgroup_lock(void);
extern int cgroup_lock_is_held(void);
extern bool cgroup_lock_live_group(struct cgroup *cgrp);
@@ -631,6 +633,7 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id);
static inline int cgroup_init_early(void) { return 0; }
static inline int cgroup_init(void) { return 0; }
+static inline void cgroup_wq_init(void) {}
static inline void cgroup_fork(struct task_struct *p) {}
static inline void cgroup_fork_callbacks(struct task_struct *p) {}
static inline void cgroup_post_fork(struct task_struct *p) {}
diff --git a/init/main.c b/init/main.c
index 2a9b88a..38907e4 100644
--- a/init/main.c
+++ b/init/main.c
@@ -727,6 +727,7 @@ static void __init do_initcalls(void)
*/
static void __init do_basic_setup(void)
{
+ cgroup_wq_init();
cpuset_init_smp();
usermodehelper_init();
shmem_init();
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1d2b6ce..6e81b14 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4371,6 +4371,25 @@ out:
return err;
}
+/**
+ * cgroup_wq_init - initialize cgroup_wq
+ *
+ * cgroup_wq is a workqueue for cgroup related tasks.
+ * Using kevent workqueue may cause deadlock when memory_migrate of cpuset
+ * is set. So we create a separate workqueue thread for cgroup.
+ */
+static struct workqueue_struct *cgroup_wq;
+void __init cgroup_wq_init(void)
+{
+ cgroup_wq = create_singlethread_workqueue("cgroup");
+ BUG_ON(!cgroup_wq);
+}
+
+void queue_cgroup_work(struct work_struct *work)
+{
+ queue_work(cgroup_wq, work);
+}
+
/*
* proc_cgroup_show()
* - Print task's cgroup paths into seq_file, one line for each hierarchy
@@ -4679,7 +4698,7 @@ static void check_for_release(struct cgroup *cgrp)
}
spin_unlock(&release_list_lock);
if (need_schedule_work)
- schedule_work(&release_agent_work);
+ queue_cgroup_work(&release_agent_work);
}
}
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 10131fd..fc63341 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -61,14 +61,6 @@
#include <linux/cgroup.h>
/*
- * Workqueue for cpuset related tasks.
- *
- * Using kevent workqueue may cause deadlock when memory_migrate
- * is set. So we create a separate workqueue thread for cpuset.
- */
-static struct workqueue_struct *cpuset_wq;
-
-/*
* Tracks how many cpusets are currently defined in system.
* When there is only one cpuset (the root cpuset) we can
* short circuit some hooks.
@@ -767,7 +759,7 @@ static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
*/
static void async_rebuild_sched_domains(void)
{
- queue_work(cpuset_wq, &rebuild_sched_domains_work);
+ queue_cgroup_work(&rebuild_sched_domains_work);
}
/*
@@ -2157,9 +2149,6 @@ void __init cpuset_init_smp(void)
top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
hotplug_memory_notifier(cpuset_track_online_nodes, 10);
-
- cpuset_wq = create_singlethread_workqueue("cpuset");
- BUG_ON(!cpuset_wq);
}
/**
--
1.7.1
--
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