linux-kernel - Re: [PATCH v12 06/13] task_isolation: support PR_TASK_ISOLATION

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Date:	Wed, 18 May 2016 12:34:59 -0400
From:	Chris Metcalf <cmetcalf@...lanox.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Gilad Ben Yossef <giladb@...hip.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>, Tejun Heo <tj@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Andy Lutomirski <luto@...capital.net>,
	<linux-doc@...r.kernel.org>, <linux-api@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v12 06/13] task_isolation: support
 PR_TASK_ISOLATION_STRICT mode

On 5/18/2016 9:44 AM, Peter Zijlstra wrote:
> On Tue, Apr 05, 2016 at 01:38:35PM -0400, Chris Metcalf wrote:
>> +void task_isolation_interrupt(struct task_struct *task, const char *buf)
>> +{
>> +	siginfo_t info = {};
>> +	int sig;
>> +
>> +	pr_warn("%s/%d: task_isolation strict mode violated by %s\n",
>> +		task->comm, task->pid, buf);
>> +
> So the function name suggests this is called for interrupts, except its
> purpose is to deliver a signal.

Fair point.  I'll name it task_isolation_deliver_signal() in the next patch series.

> Now, in case of exceptions the violation isn't necessarily _by_ the task
> itself. You might want to change that to report the exception
> type/number instead of the affected task.

Well, we do report whatever exception information we have.  For example
a page fault exception will report the address or whatever other info is
handy; it's easy to tune since it's just a vsnprintf of some varargs from the
architecture layer.

For things like IPIs or TLB invalidations or whatever, the code currently just
reports "interrupt"; I could arrange to pass down more informative varargs
from the caller for that as well.  Let me look into it.

-- 
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com