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From: Peter Zijlstra <peterz@infradead.org>
To: Mathias Krause <minipli@grsecurity.net>
Cc: "Vincent Guittot" <vincent.guittot@linaro.org>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Benjamin Segall" <bsegall@google.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Juri Lelli" <juri.lelli@redhat.com>,
	"Dietmar Eggemann" <dietmar.eggemann@arm.com>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	"Mel Gorman" <mgorman@suse.de>,
	"Daniel Bristot de Oliveira" <bristot@redhat.com>,
	"Valentin Schneider" <Valentin.Schneider@arm.com>,
	linux-kernel@vger.kernel.org, "Odin Ugedal" <odin@uged.al>,
	"Kevin Tanguy" <kevin.tanguy@corp.ovh.com>,
	"Brad Spengler" <spender@grsecurity.net>
Subject: Re: [PATCH] sched/fair: Prevent dead task groups from regaining cfs_rq's
Date: Fri, 5 Nov 2021 18:27:55 +0100	[thread overview]
Message-ID: <YYVpm7LRWMZMzxId@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <a113044b-b5b6-8bc1-864b-c817535889ff@grsecurity.net>

On Fri, Nov 05, 2021 at 06:14:33PM +0100, Mathias Krause wrote:
> Am 05.11.21 um 17:58 schrieb Peter Zijlstra:
> > On Fri, Nov 05, 2021 at 05:29:14PM +0100, Mathias Krause wrote:
> >>> Looks like it needs to be the kfree_rcu() one in this case. I'll prepare
> >>> a patch.
> >>
> >> Testing the below patch right now. Looking good so far. Will prepare a
> >> proper patch later, if we all can agree that this covers all cases.
> >>
> >> But the basic idea is to defer the kfree()'s to after the next RCU GP,
> >> which also means we need to free the tg object itself later. Slightly
> >> ugly. :/
> > 
> > Can't we add an rcu_head to struct task_group and simply call_rcu() the
> > thing with a free function?
> 
> There is already one and this patch makes use of it for the second RCU
> GP requirement. Basically, the patch is doing what you request, no? See
> the new free_fair_sched_group().

For some reason I thought you still did kfree_rcu(), I suppose reading
is hard. I'll give it another go after dinner.

  reply	other threads:[~2021-11-05 17:28 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-11 17:22 [PATCH] sched/fair: Use rq->lock when checking cfs_rq list presence Michal Koutný
2021-10-11 19:12 ` Odin Ugedal
2021-10-12 18:32   ` Tao Zhou
2021-10-13 18:52     ` Odin Ugedal
2021-10-13 14:39   ` Michal Koutný
2021-10-13 18:45     ` Odin Ugedal
2021-10-13  7:57 ` Vincent Guittot
2021-10-13 14:26   ` Michal Koutný
2021-11-02 16:02     ` task_group unthrottling and removal race (was Re: [PATCH] sched/fair: Use rq->lock when checking cfs_rq list) presence Michal Koutný
2021-11-02 20:20       ` Odin Ugedal
2021-11-03  9:51       ` Mathias Krause
2021-11-03 10:51         ` Mathias Krause
2021-11-03 11:10           ` Michal Koutný
2021-11-03 14:16             ` Mathias Krause
2021-11-03 19:06               ` [PATCH] sched/fair: Prevent dead task groups from regaining cfs_rq's Mathias Krause
2021-11-03 22:03                 ` Benjamin Segall
2021-11-04  8:50                   ` Vincent Guittot
2021-11-04 15:13                     ` Mathias Krause
2021-11-04 16:49                       ` Vincent Guittot
2021-11-04 17:37                         ` Mathias Krause
2021-11-05 14:25                           ` Vincent Guittot
2021-11-05 14:44                             ` Mathias Krause
2021-11-05 16:29                               ` Mathias Krause
2021-11-05 16:58                                 ` Peter Zijlstra
2021-11-05 17:14                                   ` Mathias Krause
2021-11-05 17:27                                     ` Peter Zijlstra [this message]
2021-11-05 17:40                                       ` Mathias Krause
2021-11-06 10:48                                 ` Peter Zijlstra
2021-11-08 10:27                                   ` Mathias Krause
2021-11-08 11:40                                     ` Peter Zijlstra
2021-11-08 15:06                                       ` Mathias Krause
2021-11-10 15:14                                         ` Vincent Guittot
2021-11-09 18:47                                       ` Michal Koutný
2021-11-10 15:17                                         ` Vincent Guittot
2021-11-04 20:46                       ` Benjamin Segall
2021-11-04 18:49                 ` Michal Koutný
2021-11-05 14:55                   ` Mathias Krause
2021-11-05 14:58                 ` Peter Zijlstra

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