mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-01-10 07:10:27 +00:00
memcg: don't register hotcpu notifier from ->css_alloc()
Commit 648bb56d076b ("cgroup: lock cgroup_mutex in cgroup_init_subsys()") made cgroup_init_subsys() grab cgroup_mutex before invoking ->css_alloc() for the root css. Because memcg registers hotcpu notifier from ->css_alloc() for the root css, this introduced circular locking dependency between cgroup_mutex and cpu hotplug. Fix it by moving hotcpu notifier registration to a subsys initcall. ====================================================== [ INFO: possible circular locking dependency detected ] 3.7.0-rc4-work+ #42 Not tainted ------------------------------------------------------- bash/645 is trying to acquire lock: (cgroup_mutex){+.+.+.}, at: [<ffffffff8110c5b7>] cgroup_lock+0x17/0x20 but task is already holding lock: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff8109300f>] cpu_hotplug_begin+0x2f/0x60 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (cpu_hotplug.lock){+.+.+.}: lock_acquire+0x97/0x1e0 mutex_lock_nested+0x61/0x3b0 get_online_cpus+0x3c/0x60 rebuild_sched_domains_locked+0x1b/0x70 cpuset_write_resmask+0x298/0x2c0 cgroup_file_write+0x1ef/0x300 vfs_write+0xa8/0x160 sys_write+0x52/0xa0 system_call_fastpath+0x16/0x1b -> #0 (cgroup_mutex){+.+.+.}: __lock_acquire+0x14ce/0x1d20 lock_acquire+0x97/0x1e0 mutex_lock_nested+0x61/0x3b0 cgroup_lock+0x17/0x20 cpuset_handle_hotplug+0x1b/0x560 cpuset_update_active_cpus+0xe/0x10 cpuset_cpu_inactive+0x47/0x50 notifier_call_chain+0x66/0x150 __raw_notifier_call_chain+0xe/0x10 __cpu_notify+0x20/0x40 _cpu_down+0x7e/0x2f0 cpu_down+0x36/0x50 store_online+0x5d/0xe0 dev_attr_store+0x18/0x30 sysfs_write_file+0xe0/0x150 vfs_write+0xa8/0x160 sys_write+0x52/0xa0 system_call_fastpath+0x16/0x1b other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(cpu_hotplug.lock); lock(cgroup_mutex); lock(cpu_hotplug.lock); lock(cgroup_mutex); *** DEADLOCK *** 5 locks held by bash/645: #0: (&buffer->mutex){+.+.+.}, at: [<ffffffff8123bab8>] sysfs_write_file+0x48/0x150 #1: (s_active#42){.+.+.+}, at: [<ffffffff8123bb38>] sysfs_write_file+0xc8/0x150 #2: (x86_cpu_hotplug_driver_mutex){+.+...}, at: [<ffffffff81079277>] cpu_hotplug_driver_lock+0x1 +7/0x20 #3: (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff81093157>] cpu_maps_update_begin+0x17/0x20 #4: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff8109300f>] cpu_hotplug_begin+0x2f/0x60 stack backtrace: Pid: 645, comm: bash Not tainted 3.7.0-rc4-work+ #42 Call Trace: print_circular_bug+0x28e/0x29f __lock_acquire+0x14ce/0x1d20 lock_acquire+0x97/0x1e0 mutex_lock_nested+0x61/0x3b0 cgroup_lock+0x17/0x20 cpuset_handle_hotplug+0x1b/0x560 cpuset_update_active_cpus+0xe/0x10 cpuset_cpu_inactive+0x47/0x50 notifier_call_chain+0x66/0x150 __raw_notifier_call_chain+0xe/0x10 __cpu_notify+0x20/0x40 _cpu_down+0x7e/0x2f0 cpu_down+0x36/0x50 store_online+0x5d/0xe0 dev_attr_store+0x18/0x30 sysfs_write_file+0xe0/0x150 vfs_write+0xa8/0x160 sys_write+0x52/0xa0 system_call_fastpath+0x16/0x1b Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
495e9d8460
commit
154b454eda
@ -6090,7 +6090,6 @@ mem_cgroup_css_alloc(struct cgroup *cont)
|
||||
&per_cpu(memcg_stock, cpu);
|
||||
INIT_WORK(&stock->work, drain_local_stock);
|
||||
}
|
||||
hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
|
||||
} else {
|
||||
parent = mem_cgroup_from_cont(cont->parent);
|
||||
memcg->use_hierarchy = parent->use_hierarchy;
|
||||
@ -6756,6 +6755,19 @@ struct cgroup_subsys mem_cgroup_subsys = {
|
||||
.use_id = 1,
|
||||
};
|
||||
|
||||
/*
|
||||
* The rest of init is performed during ->css_alloc() for root css which
|
||||
* happens before initcalls. hotcpu_notifier() can't be done together as
|
||||
* it would introduce circular locking by adding cgroup_lock -> cpu hotplug
|
||||
* dependency. Do it from a subsys_initcall().
|
||||
*/
|
||||
static int __init mem_cgroup_init(void)
|
||||
{
|
||||
hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
|
||||
return 0;
|
||||
}
|
||||
subsys_initcall(mem_cgroup_init);
|
||||
|
||||
#ifdef CONFIG_MEMCG_SWAP
|
||||
static int __init enable_swap_account(char *s)
|
||||
{
|
||||
|
Loading…
x
Reference in New Issue
Block a user