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From: Juri Lelli <juri.lelli@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@redhat.com, rostedt@goodmis.org, tj@kernel.org,
	linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it,
	claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it,
	bristot@redhat.com, mathieu.poirier@linaro.org,
	lizefan@huawei.com, cgroups@vger.kernel.org,
	Prateek Sood <prsood@codeaurora.org>
Subject: Re: [PATCH v8 6/8] cgroup/cpuset: Change cpuset_rwsem and hotplug lock order
Date: Mon, 1 Jul 2019 08:52:33 +0200	[thread overview]
Message-ID: <20190701065233.GA26005@localhost.localdomain> (raw)
In-Reply-To: <20190628130308.GU3419@hirez.programming.kicks-ass.net>

Hi,

On 28/06/19 15:03, Peter Zijlstra wrote:
> On Fri, Jun 28, 2019 at 10:06:16AM +0200, Juri Lelli wrote:
> > cpuset_rwsem is going to be acquired from sched_setscheduler() with a
> > following patch. There are however paths (e.g., spawn_ksoftirqd) in
> > which sched_scheduler() is eventually called while holding hotplug lock;
> > this creates a dependecy between hotplug lock (to be always acquired
> > first) and cpuset_rwsem (to be always acquired after hotplug lock).
> > 
> > Fix paths which currently take the two locks in the wrong order (after
> > a following patch is applied).
> > Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> 
> This all reminds me of this:
> 
>   https://lkml.kernel.org/r/1510755615-25906-1-git-send-email-prsood@codeaurora.org
> 
> Which sadly got reverted again. If we do this now (I've always been a
> proponent), then we can make that rebuild synchronous again, which
> should also help here IIRC.

Why was that reverted? Perf regression of some type?

Thanks,

Juri

  reply	other threads:[~2019-07-01  6:52 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-28  8:06 [PATCH v8 0/8] sched/deadline: fix cpusets bandwidth accounting Juri Lelli
2019-06-28  8:06 ` [PATCH v8 1/8] sched/topology: Adding function partition_sched_domains_locked() Juri Lelli
2019-06-28  8:06 ` [PATCH v8 2/8] sched/core: Streamlining calls to task_rq_unlock() Juri Lelli
2019-06-28  8:06 ` [PATCH v8 3/8] cpuset: Rebuild root domain deadline accounting information Juri Lelli
2019-06-28  8:06 ` [PATCH v8 4/8] sched/deadline: Fix bandwidth accounting at all levels after offline migration Juri Lelli
2019-06-28  8:06 ` [PATCH v8 5/8] cgroup/cpuset: convert cpuset_mutex to percpu_rwsem Juri Lelli
2019-06-28 12:45   ` Peter Zijlstra
2019-06-28 14:31     ` Juri Lelli
2019-06-28  8:06 ` [PATCH v8 6/8] cgroup/cpuset: Change cpuset_rwsem and hotplug lock order Juri Lelli
2019-06-28 13:03   ` Peter Zijlstra
2019-07-01  6:52     ` Juri Lelli [this message]
2019-07-01  8:27       ` Peter Zijlstra
2019-07-01 14:51         ` Tejun Heo
2019-07-04  8:49           ` Juri Lelli
2019-07-12 14:04             ` Juri Lelli
2019-07-16 15:36               ` Tejun Heo
2019-06-28  8:06 ` [PATCH v8 7/8] sched/core: Prevent race condition between cpuset and __sched_setscheduler() Juri Lelli
2019-07-01 19:11   ` Peter Zijlstra
2019-07-02  7:01     ` Juri Lelli
2019-06-28  8:06 ` [PATCH v8 8/8] rcu/tree: Setschedule gp ktread to SCHED_FIFO outside of atomic region Juri Lelli
2019-07-01 19:13   ` Peter Zijlstra
2019-07-02  7:01     ` Juri Lelli

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