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Re: [ckrm-tech] [PATCH 1/7] containers (V7): Generic container system abstracted from cpusets code [message #11478 is a reply to message #11474]

Sun, 25 March 2007 05:43

Paul Jackson
Messages: 157
Registered: February 2006

Senior Member

vatsa wrote:
> Not just this, continuing further we have more trouble:
>
> ------------------------------------------------------------ --------
> CPU0 (attach_task T1 to CS2) CPU1 (T1 is exiting)
> ------------------------------------------------------------ --------
>
> synchronize_rcu()
> atomic_dec(&CS1->count);
> [CS1->count = 0]
>
> if atomic_dec_and_test(&oldcs->count))
> [CS1->count = -1]
> ...
> 2nd race is tricky. We probably need to do this to avoid it:
>
> task_lock(tsk);
>
> /* Check if tsk->cpuset is still same. We may have raced with
> * cpuset_exit changing tsk->cpuset again under our feet.
> */
> if (tsk->cpuset == cs && atomic_dec_and_test(&oldcs->count)) {

I'm unsure here, but this 'tsk->cpuset == cs' test feels fragile to me.

How about a bit earlier in attach_task(), right at the point we overwrite the
victim tasks cpuset pointer, we decrement the count on the old cpuset, and if
it went to zero, remember that we'll need to release it, once we've dropped
some locks:

static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf)
{
...
struct cpuset *oldcs;
struct cpuset *oldcs_tobe_released;

...

task_lock(tsk);
oldcs = tsk->cpuset;
...
if (tsk->flags & PF_EXITING) {
...
}
atomic_inc(&cs->count);
rcu_assign_pointer(tsk->cpuset, cs);
oldcs_tobe_released = NULL;
if (atomic_dec_and_test(&oldcs->count))
oldcs_tobe_released = oldcs;
task_unlock(tsk);

...
put_task_struct(tsk);
synchronize_rcu();
if (oldcs_tobe_released)
check_for_release(oldcs_tobe_released, ppathbuf);
return 0;
}

--
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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