linux-kernel - Re: [PATCH v13 00/12] support "task

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Date:	Mon, 18 Jul 2016 15:11:42 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Chris Metcalf <cmetcalf@...lanox.com>
Cc:	Gilad Ben Yossef <giladb@...lanox.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.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>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Linux API <linux-api@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v13 00/12] support "task_isolation" mode

On Thu, Jul 14, 2016 at 2:22 PM, Chris Metcalf <cmetcalf@...lanox.com> wrote:
> On 7/14/2016 5:03 PM, Andy Lutomirski wrote:
>>
>> On Thu, Jul 14, 2016 at 1:48 PM, Chris Metcalf <cmetcalf@...lanox.com>
>> wrote:
>>>
>>> Here is a respin of the task-isolation patch set.  This primarily
>>> reflects feedback from Frederic and Peter Z.
>>
>> I still think this is the wrong approach, at least at this point.  The
>> first step should be to instrument things if necessary and fix the
>> obvious cases where the kernel gets entered asynchronously.
>
>
> Note, however, that the task_isolation_debug mode is a very convenient
> way of discovering what is going on when things do go wrong for task
> isolation.
>
>> Only once
>> there's a credible reason to believe it can work well should any form
>> of strictness be applied.
>
>
> I'm not sure what criteria you need for this, though.  Certainly we've been
> shipping our version of task isolation to customers since 2008, and there
> are quite a few customer applications in production that are working well.
> I'd argue that's a credible reason.
>
>> As an example, enough vmalloc/vfree activity will eventually cause
>> flush_tlb_kernel_range to be called and *boom*, there goes your shiny
>> production dataplane application.
>
>
> Well, that's actually a refinement that I did not inflict on this patch
> series.

Submit it separately, perhaps?

The "kill the process if it goofs" think while there are known goofs
in the kernel, apparently with patches written but unsent, seems
questionable.