linux-kernel - Re: [PATCH] x86: Remove WARN_ON(in_nmi()) from vmalloc

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Message-ID: <20131018115451.GM31306@linux.vnet.ibm.com>
Date:	Fri, 18 Oct 2013 04:54:51 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"Wang, Xiaoming" <xiaoming.wang@...el.com>,
	"Li, Zhuangzhi" <zhuangzhi.li@...el.com>,
	"Liu, Chuansheng" <chuansheng.liu@...el.com>
Subject: Re: [PATCH] x86: Remove WARN_ON(in_nmi()) from vmalloc_fault

On Wed, Oct 16, 2013 at 03:57:30PM -0400, Steven Rostedt wrote:
> On Wed, 16 Oct 2013 12:36:32 -0700
> "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> wrote:
> 
> 
> > > Ah but we have an in_interrupt() check in context_tracking_user_enter() that protects
> > > us against that.
> > 
> > Here you are relying on the exception being treated as an interrupt,
> > correct?
> 
> I don't think so. It's relying on nmi_enter() also makes in_interrupt()
> return true.

Got it, never mind!

							Thanx, Paul

> Like I said before. An NMI interrupting userspace should be no
> different than an interrupt interrupting userspace. They both can
> trigger vmalloc faults, and we should be able to deal with it.
> 
> -- Steve
> 

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