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

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Message-ID: <519D12A5.6090804@meduna.org>
Date:	Wed, 22 May 2013 20:47:01 +0200
From:	Stanislav Meduna <stano@...una.org>
To:	Rik van Riel <riel@...hat.com>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	Linus Torvalds <torvalds@...ux-foundation.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>,
	"H. Peter Anvin" <hpa@...or.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 22.05.2013 20:35, Rik van Riel wrote:

> I'm stumped.
> 
> If the Geode knows how to flush single TLB entries, it
> should do that when flush_tlb_page is called.
> 
> If it does not know, it should throw an invalid instruction
> exception, and not quietly complete the instruction without
> doing anything.

Could it be that the problem is not stale TLB, but a page directory
that is somehow invalid, e.g. belonging to the previous modprobe
(or whatever) instead of the running process?

My patch does load_cr3(next->pgd); so it explicitely loads something
there.

> In other words, make the code look like this, for testing:
>
> static inline void __native_flush_tlb_single(unsigned long addr)
> {
>         __flush_tlb();
> }

Yup, will try it.

Thanks
-- 
                                           Stano

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