From: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
To: Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Juri Lelli <juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Vincent Guittot
<vincent.guittot-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
Dietmar Eggemann <dietmar.eggemann-5wv7dgnIgG8@public.gmane.org>,
Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>,
Ben Segall <bsegall-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Mel Gorman <mgorman-l3A5Bk7waGM@public.gmane.org>,
Daniel Bristot de Oliveira
<bristot-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Valentin Schneider
<vschneid-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
Will Deacon <will-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Linus Torvalds
<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Subject: Re: [PATCH v5 1/3] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity()
Date: Wed, 17 Aug 2022 10:28:50 +0200 [thread overview]
Message-ID: <YvymwlTkdsVDtmRB@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220816192734.67115-2-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
On Tue, Aug 16, 2022 at 03:27:32PM -0400, Waiman Long wrote:
> This will be some changes in behavior for arm64 systems with asymmetric
> CPUs in some corner cases. For instance, if sched_setaffinity()
> has never been called and there is a cpuset change before
> relax_compatible_cpus_allowed_ptr() is called, its subsequent call will
> follow what the cpuset allows but not what the previous cpu affinity
> setting allows.
That's arguably a correctness fix, no? That is, the save/restore should
not have been allowed to revert to an earlier cpuset state.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <vschneid@redhat.com>,
Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Will Deacon <will@kernel.org>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v5 1/3] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity()
Date: Wed, 17 Aug 2022 10:28:50 +0200 [thread overview]
Message-ID: <YvymwlTkdsVDtmRB@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220816192734.67115-2-longman@redhat.com>
On Tue, Aug 16, 2022 at 03:27:32PM -0400, Waiman Long wrote:
> This will be some changes in behavior for arm64 systems with asymmetric
> CPUs in some corner cases. For instance, if sched_setaffinity()
> has never been called and there is a cpuset change before
> relax_compatible_cpus_allowed_ptr() is called, its subsequent call will
> follow what the cpuset allows but not what the previous cpu affinity
> setting allows.
That's arguably a correctness fix, no? That is, the save/restore should
not have been allowed to revert to an earlier cpuset state.
next prev parent reply other threads:[~2022-08-17 8:28 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 19:27 [PATCH v5 0/3] sched, cgroup/cpuset: Keep user set cpus affinity Waiman Long
2022-08-16 19:27 ` Waiman Long
[not found] ` <20220816192734.67115-1-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-08-16 19:27 ` [PATCH v5 1/3] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() Waiman Long
2022-08-16 19:27 ` Waiman Long
2022-08-17 8:41 ` Peter Zijlstra
[not found] ` <Yvyp02LLIQQPs5d6-IIpfhp3q70z/8w/KjCw3T+5/BudmfyzbbVWyRVo5IupeoWH0uzbU5w@public.gmane.org>
2022-08-18 15:31 ` Waiman Long
2022-08-18 15:31 ` Waiman Long
[not found] ` <20220816192734.67115-2-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-08-17 8:28 ` Peter Zijlstra [this message]
2022-08-17 8:28 ` Peter Zijlstra
[not found] ` <YvymwlTkdsVDtmRB-IIpfhp3q70z/8w/KjCw3T+5/BudmfyzbbVWyRVo5IupeoWH0uzbU5w@public.gmane.org>
2022-08-18 14:37 ` Waiman Long
2022-08-18 14:37 ` Waiman Long
2022-08-17 8:46 ` Peter Zijlstra
2022-08-17 8:46 ` Peter Zijlstra
2022-08-16 19:27 ` [PATCH v5 2/3] sched: Provide copy_user_cpus_mask() to copy out user mask Waiman Long
2022-08-16 19:27 ` Waiman Long
2022-08-16 19:27 ` [PATCH v5 3/3] cgroup/cpuset: Keep user set cpus affinity Waiman Long
2022-08-16 19:27 ` Waiman Long
[not found] ` <20220816192734.67115-4-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-08-16 20:15 ` Tejun Heo
2022-08-16 20:15 ` Tejun Heo
[not found] ` <Yvv66EWygCwHUCqy-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-08-16 22:11 ` Waiman Long
2022-08-16 22:11 ` Waiman Long
[not found] ` <c10e4f69-9951-6c38-6e28-fafcaec00d89-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-08-16 22:19 ` Tejun Heo
2022-08-16 22:19 ` Tejun Heo
[not found] ` <YvwX24GXadKQNp6V-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-08-17 0:13 ` Waiman Long
2022-08-17 0:13 ` Waiman Long
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