linux-kernel - Re: [PATCH]x86: flush tlb if PGD entry is changed in i386 PAE mode

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Message-ID: <1300414748.2337.137.camel@sli10-conroe>
Date:	Fri, 18 Mar 2011 10:19:08 +0800
From:	Shaohua Li <shaohua.li@...el.com>
To:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	lkml <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
	Rik van Riel <riel@...hat.com>,
	"y-goto@...fujitsu.com" <y-goto@...fujitsu.com>,
	"Mallick, Asit K" <asit.k.mallick@...el.com>
Subject: Re: [PATCH]x86: flush tlb if PGD entry is changed in i386 PAE mode

On Wed, 2011-03-16 at 21:03 +0800, Rik van Riel wrote:
> On 03/15/2011 11:37 PM, Shaohua Li wrote:
> > According to intel CPU manual, every time PGD entry is changed in i386 PAE mode,
> > we need do a full TLB flush. Current code follows this and there is comment
> > for this too in the code. But current code misses the multi-threaded case. A
> > changed page table might be used by several CPUs, every such CPU should flush
> > TLB.
> > Usually this isn't a problem, because we prepopulate all PGD entries at process
> > fork. But when the process does munmap and follows new mmap, this issue will be
> > triggered. When it happens, some CPUs will keep doing page fault.
> >
> > See: http://marc.info/?l=linux-kernel&m=129915020508238&w=2
> >
> > Reported-by: Yasunori Goto<y-goto@...fujitsu.com>
> > Signed-off-by: Shaohua Li<shaohua.li@...el.com>
> > Tested-by: Yasunori Goto<y-goto@...fujitsu.com>
> 
> Reviewed-by: Rik van Riel <riel@...hat.com>
Ingo & akpm,
can you pick this one?

Thanks,
Shaohua

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