From: Steven Rostedt <rostedt@goodmis.org>
To: tip-bot for Peter Zijlstra <tipbot@zytor.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, guro@fb.com,
peterz@infradead.org, hpa@zytor.com, dave@stgolabs.net,
tim.c.chen@linux.intel.com, rostedt@goodmis.org, ast@kernel.org,
torvalds@linux-foundation.org, longman@redhat.com,
will.deacon@arm.com, huang.ying.caritas@gmail.com,
daniel@iogearbox.net, tglx@linutronix.de,
linux-tip-commits@vger.kernel.org
Subject: Re: [tip:sched/core] trace: Fix preempt_enable_no_resched() abuse
Date: Mon, 29 Apr 2019 09:31:17 -0400 [thread overview]
Message-ID: <20190429093117.23760399@gandalf.local.home> (raw)
In-Reply-To: <tip-e8bd5814989b994cf1b0cb179e1c777e40c0f02c@git.kernel.org>
On Sun, 28 Apr 2019 23:39:03 -0700
tip-bot for Peter Zijlstra <tipbot@zytor.com> wrote:
> Commit-ID: e8bd5814989b994cf1b0cb179e1c777e40c0f02c
> Gitweb: https://git.kernel.org/tip/e8bd5814989b994cf1b0cb179e1c777e40c0f02c
> Author: Peter Zijlstra <peterz@infradead.org>
> AuthorDate: Tue, 23 Apr 2019 22:03:18 +0200
> Committer: Ingo Molnar <mingo@kernel.org>
> CommitDate: Mon, 29 Apr 2019 08:27:09 +0200
>
> trace: Fix preempt_enable_no_resched() abuse
Hi Ingo,
I already sent this fix to Linus, and it's been pulled in to his tree.
Commit: d6097c9e4454adf1f8f2c9547c2fa6060d55d952
-- Steve
>
> Unless there is a call into schedule() in the immediate
> (deterministic) future, one must not use preempt_enable_no_resched().
> It can cause a preemption to go missing and thereby cause arbitrary
> delays, breaking the PREEMPT=y invariant.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Roman Gushchin <guro@fb.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Tim Chen <tim.c.chen@linux.intel.com>
> Cc: Waiman Long <longman@redhat.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: huang ying <huang.ying.caritas@gmail.com>
> Fixes: 2c2d7329d8af ("tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()")
> Link: https://lkml.kernel.org/r/20190423200318.GY14281@hirez.programming.kicks-ass.net
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> ---
> kernel/trace/ring_buffer.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 41b6f96e5366..4ee8d8aa3d0f 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -762,7 +762,7 @@ u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
>
> preempt_disable_notrace();
> time = rb_time_stamp(buffer);
> - preempt_enable_no_resched_notrace();
> + preempt_enable_notrace();
>
> return time;
> }
next prev parent reply other threads:[~2019-04-29 13:31 UTC|newest]
Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-13 17:22 [PATCH v4 00/16] locking/rwsem: Rwsem rearchitecture part 2 Waiman Long
2019-04-13 17:22 ` [PATCH v4 01/16] locking/rwsem: Prevent unneeded warning during locking selftest Waiman Long
2019-04-18 8:04 ` [tip:locking/core] " tip-bot for Waiman Long
2019-04-13 17:22 ` [PATCH v4 02/16] locking/rwsem: Make owner available even if !CONFIG_RWSEM_SPIN_ON_OWNER Waiman Long
2019-04-13 17:22 ` [PATCH v4 03/16] locking/rwsem: Remove rwsem_wake() wakeup optimization Waiman Long
2019-04-13 17:22 ` [PATCH v4 04/16] locking/rwsem: Implement a new locking scheme Waiman Long
2019-04-16 13:22 ` Peter Zijlstra
2019-04-16 13:32 ` Waiman Long
2019-04-16 14:18 ` Peter Zijlstra
2019-04-16 14:42 ` Peter Zijlstra
2019-04-13 17:22 ` [PATCH v4 05/16] locking/rwsem: Merge rwsem.h and rwsem-xadd.c into rwsem.c Waiman Long
2019-04-13 17:22 ` [PATCH v4 06/16] locking/rwsem: Code cleanup after files merging Waiman Long
2019-04-16 16:01 ` Peter Zijlstra
2019-04-16 16:17 ` Peter Zijlstra
2019-04-16 19:45 ` Waiman Long
2019-04-13 17:22 ` [PATCH v4 07/16] locking/rwsem: Implement lock handoff to prevent lock starvation Waiman Long
2019-04-16 14:12 ` Peter Zijlstra
2019-04-16 20:26 ` Waiman Long
2019-04-16 21:07 ` Waiman Long
2019-04-17 7:13 ` Peter Zijlstra
2019-04-17 16:22 ` Waiman Long
2019-04-16 15:49 ` Peter Zijlstra
2019-04-16 16:15 ` Peter Zijlstra
2019-04-16 18:41 ` Waiman Long
2019-04-16 18:16 ` Waiman Long
2019-04-16 18:32 ` Peter Zijlstra
2019-04-17 7:35 ` Peter Zijlstra
2019-04-17 16:35 ` Waiman Long
2019-04-17 8:05 ` Peter Zijlstra
2019-04-17 16:39 ` Waiman Long
2019-04-18 8:22 ` Peter Zijlstra
2019-04-17 8:17 ` Peter Zijlstra
2019-04-13 17:22 ` [PATCH v4 08/16] locking/rwsem: Make rwsem_spin_on_owner() return owner state Waiman Long
2019-04-17 9:00 ` Peter Zijlstra
2019-04-17 16:42 ` Waiman Long
2019-04-17 10:19 ` Peter Zijlstra
2019-04-17 16:53 ` Waiman Long
2019-04-17 12:41 ` Peter Zijlstra
2019-04-17 12:47 ` Peter Zijlstra
2019-04-17 18:29 ` Waiman Long
2019-04-18 8:39 ` Peter Zijlstra
2019-04-17 13:00 ` Peter Zijlstra
2019-04-17 18:50 ` Waiman Long
2019-04-13 17:22 ` [PATCH v4 09/16] locking/rwsem: Ensure an RT task will not spin on reader Waiman Long
2019-04-17 13:18 ` Peter Zijlstra
2019-04-17 18:47 ` Waiman Long
2019-04-18 8:52 ` Peter Zijlstra
2019-04-18 13:27 ` Waiman Long
2019-04-13 17:22 ` [PATCH v4 10/16] locking/rwsem: Wake up almost all readers in wait queue Waiman Long
2019-04-16 16:50 ` Davidlohr Bueso
2019-04-16 17:37 ` Waiman Long
2019-04-17 13:39 ` Peter Zijlstra
2019-04-17 17:16 ` Waiman Long
2019-04-13 17:22 ` [PATCH v4 11/16] locking/rwsem: Enable readers spinning on writer Waiman Long
2019-04-17 13:56 ` Peter Zijlstra
2019-04-17 17:34 ` Waiman Long
2019-04-18 8:57 ` Peter Zijlstra
2019-04-18 14:35 ` Waiman Long
2019-04-17 13:58 ` Peter Zijlstra
2019-04-17 17:45 ` Waiman Long
2019-04-18 9:00 ` Peter Zijlstra
2019-04-18 13:40 ` Waiman Long
2019-04-17 14:05 ` Peter Zijlstra
2019-04-17 17:51 ` Waiman Long
2019-04-18 9:11 ` Peter Zijlstra
2019-04-18 14:37 ` Waiman Long
2019-04-13 17:22 ` [PATCH v4 12/16] locking/rwsem: Enable time-based spinning on reader-owned rwsem Waiman Long
2019-04-18 13:06 ` Peter Zijlstra
2019-04-18 15:15 ` Waiman Long
2019-04-19 7:56 ` Peter Zijlstra
2019-04-19 14:33 ` Waiman Long
2019-04-19 15:36 ` Waiman Long
2019-04-13 17:22 ` [PATCH v4 13/16] locking/rwsem: Add more rwsem owner access helpers Waiman Long
2019-04-13 17:22 ` [PATCH v4 14/16] locking/rwsem: Guard against making count negative Waiman Long
2019-04-18 13:51 ` Peter Zijlstra
2019-04-18 14:08 ` Waiman Long
2019-04-18 14:30 ` Peter Zijlstra
2019-04-18 14:40 ` Peter Zijlstra
2019-04-18 14:54 ` Waiman Long
2019-04-19 10:26 ` Peter Zijlstra
2019-04-19 12:02 ` Peter Zijlstra
2019-04-19 13:03 ` Peter Zijlstra
2019-04-19 13:15 ` Peter Zijlstra
2019-04-19 19:39 ` Waiman Long
2019-04-21 21:07 ` Waiman Long
2019-04-23 14:17 ` Peter Zijlstra
2019-04-23 14:31 ` Waiman Long
2019-04-23 16:27 ` Linus Torvalds
2019-04-23 19:12 ` Waiman Long
2019-04-23 19:34 ` Peter Zijlstra
2019-04-23 19:41 ` Waiman Long
2019-04-23 19:55 ` [PATCH] bpf: Fix preempt_enable_no_resched() abuse Peter Zijlstra
2019-04-23 20:03 ` [PATCH] trace: " Peter Zijlstra
2019-04-23 23:58 ` Steven Rostedt
2019-04-29 6:39 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2019-04-29 13:31 ` Steven Rostedt [this message]
2019-04-29 14:08 ` Ingo Molnar
2019-04-23 20:27 ` [PATCH] bpf: " Linus Torvalds
2019-04-23 20:35 ` Peter Zijlstra
2019-04-23 20:45 ` Linus Torvalds
2019-04-24 13:19 ` Peter Zijlstra
2019-04-25 21:23 ` Alexei Starovoitov
2019-04-26 7:14 ` Peter Zijlstra
2019-04-24 7:09 ` [PATCH v4 14/16] locking/rwsem: Guard against making count negative Peter Zijlstra
2019-04-24 16:49 ` Waiman Long
2019-04-24 17:01 ` Peter Zijlstra
2019-04-24 17:10 ` Waiman Long
2019-04-24 17:56 ` Linus Torvalds
2019-04-13 17:22 ` [PATCH v4 15/16] locking/rwsem: Merge owner into count on x86-64 Waiman Long
2019-04-18 14:28 ` Peter Zijlstra
2019-04-18 14:40 ` Waiman Long
2019-04-13 17:22 ` [PATCH v4 16/16] locking/rwsem: Remove redundant computation of writer lock word Waiman Long
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