From: Peter Zijlstra <peterz@infradead.org>
To: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Gilad Ben Yossef <giladb@ezchip.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Christoph Lameter <cl@linux.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Andy Lutomirski <luto@amacapital.net>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v12 07/13] task_isolation: add debug boot flag
Date: Wed, 18 May 2016 19:06:47 +0200 [thread overview]
Message-ID: <20160518170647.GL3193@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <684587d7-3653-7570-215f-37d3e9e786bc@mellanox.com>
On Wed, May 18, 2016 at 12:35:19PM -0400, Chris Metcalf wrote:
> On 5/18/2016 9:56 AM, Peter Zijlstra wrote:
> >On Tue, Apr 05, 2016 at 01:38:36PM -0400, Chris Metcalf wrote:
> >>+#ifdef CONFIG_TASK_ISOLATION
> >>+void task_isolation_debug(int cpu)
> >>+{
> >>+ struct task_struct *p;
> >>+
> >>+ if (!task_isolation_possible(cpu))
> >>+ return;
> >>+
> >>+ rcu_read_lock();
> >>+ p = cpu_curr(cpu);
> >>+ get_task_struct(p);
> >>+ rcu_read_unlock();
> >>+ task_isolation_debug_task(cpu, p);
> >>+ put_task_struct(p);
> >
> >This is still broken...
>
> I don't know how or why, though. :-) Can you give me a better idiom?
> This looks to my eye just like how it's done for something like
> sched_setaffinity() by one task on another task, and I would have
> assumed the risks there of the other task evaporating part way
> through would be the same as the risks here.
Because rcu_read_lock() does not stop the task pointed to by
cpu_curr(cpu) from disappearing on you entirely.
See also the discussion around:
lkml.kernel.org/r/20160518170218.GY3192@twins.programming.kicks-ass.net
next prev parent reply other threads:[~2016-05-18 17:07 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-05 17:38 [PATCH v12 00/13] support "task_isolation" mode Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 01/13] vmstat: add quiet_vmstat_sync function Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 02/13] vmstat: add vmstat_idle function Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 03/13] lru_add_drain_all: factor out lru_add_drain_needed Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 04/13] task_isolation: add initial support Chris Metcalf
2016-05-18 13:34 ` Peter Zijlstra
2016-05-18 16:34 ` Chris Metcalf
2016-05-18 17:09 ` Peter Zijlstra
2016-04-05 17:38 ` [PATCH v12 05/13] task_isolation: support CONFIG_TASK_ISOLATION_ALL Chris Metcalf
2016-05-18 13:35 ` Peter Zijlstra
2016-05-18 16:34 ` Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 06/13] task_isolation: support PR_TASK_ISOLATION_STRICT mode Chris Metcalf
2016-05-18 13:44 ` Peter Zijlstra
2016-05-18 16:34 ` Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 07/13] task_isolation: add debug boot flag Chris Metcalf
2016-05-18 13:56 ` Peter Zijlstra
2016-05-18 16:36 ` Chris Metcalf
[not found] ` <684587d7-3653-7570-215f-37d3e9e786bc@mellanox.com>
2016-05-18 17:06 ` Peter Zijlstra [this message]
2016-05-19 15:12 ` Chris Metcalf
[not found] ` <b22cf841-9555-fff3-435b-646c4fd95bdc@mellanox.com>
2016-05-19 17:54 ` Peter Zijlstra
2016-05-19 18:05 ` Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 08/13] task_isolation: add PR_TASK_ISOLATION_ONE_SHOT flag Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 09/13] arm, tile: turn off timer tick for oneshot_stopped state Chris Metcalf
2016-04-07 16:58 ` Daniel Lezcano
2016-04-05 17:38 ` [PATCH v12 10/13] arch/x86: enable task isolation functionality Chris Metcalf
2016-05-18 16:23 ` Peter Zijlstra
2016-05-18 16:35 ` Chris Metcalf
2016-05-18 17:10 ` Peter Zijlstra
2016-04-05 17:38 ` [PATCH v12 11/13] arch/tile: " Chris Metcalf
2016-04-05 17:38 ` [PATCH v12 12/13] arm64: factor work_pending state machine to C Chris Metcalf
2016-07-08 15:43 ` [PATCH]: " Chris Metcalf
2016-07-08 15:49 ` Will Deacon
2016-07-08 16:11 ` Chris Metcalf
2016-07-11 11:42 ` Will Deacon
2016-07-11 12:19 ` Mark Rutland
2016-07-29 18:16 ` Chris Metcalf
2016-08-09 10:21 ` Will Deacon
2016-04-05 17:38 ` [PATCH v12 13/13] arch/arm64: enable task isolation functionality Chris Metcalf
2016-05-12 18:26 ` [PATCH v12 00/13] support "task_isolation" mode Chris Metcalf
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