linux-kernel - Re: slab: setup allocators earlier in the boot sequence

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: <1244815370.7172.169.camel@pasglop>
Date:	Sat, 13 Jun 2009 00:02:50 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, mingo@...e.hu,
	akpm@...ux-foundation.org, npiggin@...e.de
Subject: Re: slab: setup allocators earlier in the boot sequence

On Fri, 2009-06-12 at 16:54 +0300, Pekka Enberg wrote:
> Hi Christoph,
> 
> On Fri, 2009-06-12 at 09:49 -0400, Christoph Lameter wrote:
> > Best thing to do is to recognize the fact that we are still in early boot
> > in the allocators. Derived allocators (such as slab and vmalloc) mask bits
> > using GFP_RECLAIM_MASK and when doing allocations through the page
> > allocator. You could make GFP_RECLAIM_MASK a variable. During boot
> > __GFP_WAIT would not be set in GFP_RECLAIM_MASK.
> 
> Ben's patch does something like that and I have patches that do that
> floating around too.
> 
> The problem here is that it's not enough that we make GFP_RECLAIM_MASK a
> variable. There are various _debugging checks_ that happen much earlier
> than that. We need to mask out those too which adds overhead to
> kmalloc() fastpath, for example.

Hrm... I though I stuck my masking before the lockdep tests but maybe I
missed some...

Again, I'm not saying my patch is the best way to solve it. My point is
more that the callers shouldn't have to bother. (And thus the WARN_ON
isn't right :-)

Cheers,
Ben.


--
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/