linux-kernel - Re: CMA alignment question

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] [day] [month] [year] [list]

Message-ID: <xa1td290ikax.fsf@mina86.com>
Date:	Thu, 06 Nov 2014 13:29:42 +0100
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Weijie Yang <weijie.yang.kh@...il.com>
Cc:	Gregory Fong <gregory.0xf0@...il.com>, linux-mm@...ck.org,
	Laura Abbott <lauraa@...eaurora.org>, iamjoonsoo.kim@....com,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Brian Norris <computersforpeace@...il.com>
Subject: Re: CMA alignment question

On Thu, Nov 06 2014, Weijie Yang <weijie.yang.kh@...il.com> wrote:
> I agree the current code doesn't handle this issue properly.
> However, I prefer to add specific usage to CMA interface rather than
> modify the cma code, Because the latter hide the issue and could waste
> memory.

cma_alloc should handle whatever alignment caller uses.  Sure, if CMA
area has smaller alignment this may lead to wasted memory, but so can
allocation with small alignment followed by allocation with big
alignment.

If you're saying that platform should try to get the CMA area aligned
such that no alignment offset happens I agree.  If you're saying that
cma_alloc should fail (to properly align) an allocation request,
I disagree.

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
--
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/