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Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code [message #11475 is a reply to message #11473]

Sun, 25 March 2007 04:45

Paul Jackson
Messages: 157
Registered: February 2006

Senior Member

vatsa wrote:
> Now consider:

Nice work - thanks. Yes, both an extra cpuset count and a negative
cpuset count are bad news, opening the door to the usual catastrophes.

Would you like the honor of submitting the patch to add a task_lock
to cpuset_exit()? If you do, be sure to fix, or at least remove,
the cpuset_exit comment lines:

* We don't need to task_lock() this reference to tsk->cpuset,
* because tsk is already marked PF_EXITING, so attach_task() won't
* mess with it, or task is a failed fork, never visible to attach_task.

I guess that taking task_lock() in cpuset_exit() should not be a serious
performance issue. It's taking a spinlock that is in the current
exiting tasks task struct, so it should be a cache hot memory line and
a rarely contested lock.

And I guess I've not see this race in real life, as one side of it has
to execute quite a bit of code in the task exit path, from when it sets
PF_EXITING until it gets into the cpuset_exit() call, while the other side
does the three lines:

if (tsk->flags & PF_EXITING) ...
atomic_inc(&cs->count);
rcu_assign_pointer(tsk->cpuset, cs);

So, in real life, this would be a difficult race to trigger.

Thanks for finding this.

--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@sgi.com> 1.925.600.0401

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[Message index]

		[PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Mon, 12 February 2007 08:15
		[PATCH 2/7] containers (V7): Cpusets hooked into containers By: Paul Menage on Mon, 12 February 2007 08:15
		Re: [PATCH 2/7] containers (V7): Cpusets hooked into containers By: Paul Menage on Thu, 15 February 2007 20:49
		Re: [PATCH 2/7] containers (V7): Cpusets hooked into containers By: serue on Thu, 15 February 2007 20:35
		Re: [PATCH 2/7] containers (V7): Cpusets hooked into containers By: Srivatsa Vaddagiri on Wed, 07 March 2007 14:34
		Re: [PATCH 2/7] containers (V7): Cpusets hooked into containers By: Paul Menage on Wed, 07 March 2007 16:01
		Re: [ckrm-tech] [PATCH 2/7] containers (V7): Cpusets hooked into containers By: Srivatsa Vaddagiri on Wed, 07 March 2007 16:24
		Re: [ckrm-tech] [PATCH 2/7] containers (V7): Cpusets hooked into containers By: Paul Menage on Wed, 07 March 2007 16:31
		Re: [PATCH 2/7] containers (V7): Cpusets hooked into containers By: Srivatsa Vaddagiri on Wed, 07 March 2007 14:52
		Re: [PATCH 2/7] containers (V7): Cpusets hooked into containers By: Paul Menage on Wed, 07 March 2007 16:12
		[PATCH 4/7] containers (V7): Simple CPU accounting container subsystem By: Paul Menage on Mon, 12 February 2007 08:15
		[PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: Paul Menage on Mon, 12 February 2007 08:15
		Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: Srivatsa Vaddagiri on Sat, 24 March 2007 04:58
		Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: serue on Mon, 26 March 2007 21:55
		Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: Srivatsa Vaddagiri on Sat, 24 March 2007 16:23
		Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: serue on Mon, 26 March 2007 21:57
		Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: Srivatsa Vaddagiri on Wed, 28 March 2007 14:55
		Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: Srivatsa Vaddagiri on Sat, 31 March 2007 02:47
		Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem By: serue on Mon, 02 April 2007 14:09
		[PATCH 6/7] containers (V7): BeanCounters over generic process containers By: Paul Menage on Mon, 12 February 2007 08:15
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: Srivatsa Vaddagiri on Mon, 12 February 2007 15:34
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: Paul Menage on Mon, 12 February 2007 18:49
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: xemul on Tue, 13 February 2007 08:52
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: Paul Menage on Tue, 13 February 2007 09:03
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: xemul on Tue, 13 February 2007 09:18
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: Paul Menage on Tue, 13 February 2007 09:37
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: xemul on Tue, 13 February 2007 09:49
		Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers By: Paul Menage on Thu, 15 February 2007 00:47
		[PATCH 5/7] containers (V7): Resource Groups over generic containers By: Paul Menage on Mon, 12 February 2007 08:15
		[PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Menage on Mon, 12 February 2007 08:15
		Re: [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Menage on Mon, 12 February 2007 19:26
		Re: [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Menage on Mon, 12 February 2007 19:46
		Re: [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Tue, 13 February 2007 05:48
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Tue, 13 February 2007 08:16
		Re: [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Wed, 07 March 2007 12:21
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Wed, 07 March 2007 14:06
		Re: [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Menage on Wed, 07 March 2007 20:50
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Thu, 08 March 2007 10:31
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Menage on Thu, 08 March 2007 10:40
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Jackson on Sun, 11 March 2007 19:38
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Mon, 12 March 2007 14:19
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Thu, 22 March 2007 09:56
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Thu, 22 March 2007 10:20
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Sat, 24 March 2007 14:58
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Jackson on Sat, 24 March 2007 19:25
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Sun, 25 March 2007 00:38
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Jackson on Sun, 25 March 2007 01:41
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Sun, 25 March 2007 02:21
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Sun, 25 March 2007 04:16
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Jackson on Sun, 25 March 2007 05:43
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Sun, 25 March 2007 08:14
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Jackson on Sun, 25 March 2007 04:45
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Srivatsa Vaddagiri on Sun, 25 March 2007 04:57
		Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code By: Paul Jackson on Sun, 25 March 2007 04:59
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Jackson on Mon, 12 February 2007 09:18
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Mon, 12 February 2007 09:32
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Jackson on Mon, 12 February 2007 09:52
		[PATCH 3/7] containers (V7): Add generic multi-subsystem API to containers By: Paul Menage on Mon, 12 February 2007 08:15
		Re: [PATCH 3/7] containers (V7): Add generic multi-subsystem API to containers By: Paul Menage on Mon, 12 February 2007 18:31
		Re: [PATCH 3/7] containers (V7): Add generic multi-subsystem API to containers By: Cedric Le Goater on Mon, 12 February 2007 15:56
		Re: [PATCH 3/7] containers (V7): Add generic multi-subsystem API to containers By: Balbir Singh on Wed, 14 February 2007 08:49
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Mon, 12 February 2007 23:15
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Sam Vilain on Tue, 13 February 2007 00:30
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: ebiederm on Tue, 20 February 2007 17:34
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Mon, 12 February 2007 23:18
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: serue on Mon, 12 February 2007 22:47
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Sam Vilain on Mon, 12 February 2007 22:38
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Tue, 20 February 2007 17:55
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: ebiederm on Tue, 20 February 2007 19:29
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Tue, 20 February 2007 22:47
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: serue on Tue, 20 February 2007 23:32
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Sam Vilain on Tue, 20 February 2007 23:08
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Sam Vilain on Tue, 20 February 2007 21:58
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Tue, 20 February 2007 22:19
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Sam Vilain on Tue, 20 February 2007 22:58
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Tue, 20 February 2007 23:28
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: Paul Menage on Tue, 20 February 2007 23:36
		Re: [PATCH 0/7] containers (V7): Generic Process Containers By: serue on Tue, 20 February 2007 23:37

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