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>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Lai Jiangshan <jiangshanlai@gmail.com>
Subject: Re: [PATCH v10 4/5] sched: Handle set_cpus_allowed_ptr(), sched_setaffinity() & other races
Date: Fri, 7 Oct 2022 14:47:19 +0200 [thread overview]
Message-ID: <Y0Af1zT1QQrMo8hf@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20220922180041.1768141-5-longman@redhat.com>
On Thu, Sep 22, 2022 at 02:00:40PM -0400, Waiman Long wrote:
> Racing is possible between set_cpus_allowed_ptr() and sched_setaffinity()
> or between multiple sched_setaffinity() calls from different
> CPUs. To resolve these race conditions, we need to update both
> user_cpus_ptr and cpus_mask in a single lock critical section instead
> of separated ones. This requires moving the user_cpus_ptr update
> to set_cpus_allowed_common() by putting the user_mask into a new
> affinity_context structure and using it to pass information around
> various functions.
>
> This patch also changes the handling of the race between the
> sched_setaffinity() call and the changing of cpumask of the current
> cpuset. In case the new mask conflicts with newly updated cpuset,
> the cpus_mask will be reset to the cpuset cpumask and an error value
> of -EINVAL will be returned. If a previous user_cpus_ptr value exists,
> it will be swapped back in and the new_mask will be further restricted
> to what is allowed in the cpumask pointed to by the old user_cpus_ptr.
>
> The potential race between sched_setaffinity() and a fork/clone()
> syscall calling dup_user_cpus_ptr() is also being handled.
This is still arse-backwards... You're still fixing races you've
introduced earlier in the series.
Since I don't think telling you again is going to help; I've done it for
you :/ How's this then?
https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=sched/affinity
next prev parent reply other threads:[~2022-10-07 12:47 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 18:00 [PATCH v10 0/5] sched: Persistent user requested affinity Waiman Long
2022-09-22 18:00 ` [PATCH v10 1/5] sched: Add __releases annotations to affine_move_task() Waiman Long
2022-10-28 6:42 ` [tip: sched/core] " tip-bot2 for Waiman Long
2022-09-22 18:00 ` [PATCH v10 2/5] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() Waiman Long
2022-10-28 6:42 ` [tip: sched/core] sched: Always preserve the user requested cpumask tip-bot2 for Waiman Long
2023-01-17 16:08 ` [PATCH v10 2/5] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() Will Deacon
2023-01-17 18:13 ` Waiman Long
2023-01-20 17:59 ` Will Deacon
2023-01-20 18:10 ` Waiman Long
2023-01-26 12:52 ` Linux kernel regression tracking (#adding)
2023-02-10 17:15 ` Linux kernel regression tracking (#update)
2023-01-27 18:36 ` Peter Zijlstra
2023-01-27 19:09 ` Waiman Long
2022-09-22 18:00 ` [PATCH v10 3/5] sched: Enforce user requested affinity Waiman Long
2022-10-07 10:01 ` Peter Zijlstra
2022-10-07 14:57 ` Waiman Long
2022-10-07 15:23 ` Waiman Long
2022-10-28 6:42 ` [tip: sched/core] " tip-bot2 for Waiman Long
2022-09-22 18:00 ` [PATCH v10 4/5] sched: Handle set_cpus_allowed_ptr(), sched_setaffinity() & other races Waiman Long
2022-10-07 12:47 ` Peter Zijlstra [this message]
2022-10-07 18:59 ` Waiman Long
2022-10-28 6:42 ` [tip: sched/core] sched: Introduce affinity_context tip-bot2 for Waiman Long
2022-09-22 18:00 ` [PATCH v10 5/5] sched: Always clear user_cpus_ptr in do_set_cpus_allowed() Waiman Long
2022-10-28 6:42 ` [tip: sched/core] " tip-bot2 for Waiman Long
2022-10-06 21:31 ` [PATCH v10 0/5] sched: Persistent user requested affinity Waiman Long
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