linux-kernel - Re: [PATCH] mm: fix up a spurious page fault whenever it happens

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Message-ID: <51C340DE.30806@meduna.org>
Date:	Thu, 20 Jun 2013 19:50:22 +0200
From:	Stanislav Meduna <stano@...una.org>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	"linux-rt-users@...r.kernel.org" <linux-rt-users@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Hai Huang <hhuang@...hat.com>
Subject: Re: [PATCH] mm: fix up a spurious page fault whenever it happens

On 19.06.2013 10:06, Peter Zijlstra wrote:

>> On 19.06.2013 07:20, Linus Torvalds wrote:
>>> There's the fast_tlb race that Peter fixed in commit 29eb77825cc7
>>> ("arch, mm: Remove tlb_fast_mode()"). I'm not seeing how it would
>>> cause infinite TLB faults, but it definitely causes potentially
>>> incoherent TLB contents. And afaik it only happens with
>>> CONFIG_PREEMPT, and on UP systems. Which sounds like it might match
>>> your setup...

> The easiest way to test for your system is to ensure tlb_fast_mode()
> return an unconditional 0.

Nope. Got the faults also with tlb_fast_mode() returning 0, this time
after ~10 hours. So there still has to be something...

Regards
-- 
                                        Stano


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