linux-kernel - Re: [RFC PATCH] ARM: mm: disable kmap_high

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]

Message-ID: <alpine.LFD.2.03.1303051642110.28820@syhkavp.arg>
Date:	Tue, 5 Mar 2013 17:36:12 +0800 (HKT)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
cc:	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] ARM: mm: disable kmap_high_get() for SMP

On Mon, 4 Mar 2013, Joonsoo Kim wrote:

> With SMP and enabling kmap_high_get(), it makes users of kmap_atomic()
> sequential ordered, because kmap_high_get() use global kmap_lock().
> It is not welcome situation, so turn off this optimization for SMP.

I'm not sure I understand the problem.

The lock taken by kmap_high_get() is released right away before that 
function returns and therefore this is not actually serializing 
anything.


Nicolas
--
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/