linux-kernel - Re: [RFC PATCH 0/6] TLB flush multiple pages with a single IPI v3

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Message-ID: <20150424151652.GC2449@suse.de>
Date:	Fri, 24 Apr 2015 16:16:52 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	Linux-MM <linux-mm@...ck.org>, Rik van Riel <riel@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Minchan Kim <minchan@...nel.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 0/6] TLB flush multiple pages with a single IPI v3

On Fri, Apr 24, 2015 at 04:46:22PM +0200, Vlastimil Babka wrote:
> On 04/21/2015 12:41 PM, Mel Gorman wrote:
> >Changelog since V2
> >o Ensure TLBs are flushed before pages are freed		(mel)
> 
> I admit not reading all the patches thoroughly, but doesn't this
> change of ordering mean that you no longer need the architectural
> guarantee discussed in patch 2?

No. If we unmap a page to write it to disk then we cannot allow a CPU to
write to the physical page being written through a cached entry.

-- 
Mel Gorman
SUSE Labs
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