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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 19 Jun 2013 10:06:56 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Stanislav Meduna <stano@...una.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 Wed, Jun 19, 2013 at 09:36:39AM +0200, Stanislav Meduna wrote:
> On 19.06.2013 07:20, Linus Torvalds wrote:
> 
> >> No crash in 2 days running with preempt none...
> > 
> > Is this UP?
> 
> Yes it is.
> 
> > 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...
> 
> Oh, thank you for the pointer, this indeed looks interesting.
> 
> Unfortunately the patch massively does not apply to 3.4 which
> I am using and I know too little what all is involved here
> to backport it. I will test it when (if) it gets to the 3.4(-rt)
> (or when I find some spare time to play with the newer kernel
> on that system).

The easiest way to test for your system is to ensure tlb_fast_mode()
return an unconditional 0.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/