linux-kernel - Re: [PATCH 1/2] mmap.2: clarify MAP

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Message-ID: <573314ED.4090704@infradead.org>
Date:	Wed, 11 May 2016 13:18:05 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Michal Hocko <miso@...p22.suse.cz>,
	Michael Kerrisk <mtk.manpages@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux API <linux-api@...r.kernel.org>, linux-mm@...ck.org,
	Michal Hocko <mhocko@...e.cz>
Subject: Re: [PATCH 1/2] mmap.2: clarify MAP_LOCKED semantic



On 05/11/2016 01:07 PM, Peter Zijlstra wrote:
> On 05/13/2015 04:38 PM, Michal Hocko wrote:
>>
>> This patch makes the semantic of MAP_LOCKED explicit and suggest using
>> mmap + mlock as the only way to guarantee no later major page faults.
>>
>
> URGH, this really blows chunks. It basically means MAP_LOCKED is 
> pointless cruft and we might as well remove it.
>
> Why not fix it proper?

OK; after having been pointed at this discussion, it seems I reacted rather
too hasty in that I didn't read all the previous threads.

 From that it appears fixing this proper is indeed rather hard, and we 
should
indeed consider MAP_LOCKED broken. At which point I would've worded the
manpage update stronger, but alas.

Sorry for the noise.