linux-kernel - Re: [PATCH 1/3] swiotlb: Warn on allocation failure in swiotlb_alloc

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: <20141203102652.GL3156@suse.de>
Date:	Wed, 3 Dec 2014 11:26:52 +0100
From:	Joerg Roedel <jroedel@...e.de>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Joerg Roedel <joro@...tes.org>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] swiotlb: Warn on allocation failure in
 swiotlb_alloc_coherent

On Tue, Dec 02, 2014 at 01:46:15PM -0500, Konrad Rzeszutek Wilk wrote:
> On Tue, Dec 02, 2014 at 03:41:22PM +0100, Joerg Roedel wrote:
> > On Mon, Dec 01, 2014 at 03:28:03PM -0500, Konrad Rzeszutek Wilk wrote:
> > > On Fri, Nov 28, 2014 at 12:29:07PM +0100, Joerg Roedel wrote:
> > > > From: Joerg Roedel <jroedel@...e.de>
> > > > 
> > > > Print a warning when all allocation tries have been failed
> > > > and the function is about to return NULL. This prepares for
> > > > calling the function with __GFP_NOWARN to suppress
> > > > allocation failure warnings before all fall-backs have
> > > > failed.
> > > 
> > > This can be quite noisy. Especially the dump-stack.
> > 
> > Well, this is as noisy as the dump_stack()s from the page-allocator when
> > the first allocation try fails. The goal of the first two patches in
> 
> Right, on the first allocation. Subsequent allocations won't be so noisy
> in the page-allocator (I think?).

>From the code in mm/page_alloc.c (function warn_alloc_failed) it doesn't
look like a one-time warning. The dmesg I have seen from a failing
kernel also shows a lot of these messages.

So having the warning at the end of swiotlb_alloc_coherent won't be any
more noisy than the (removed) warnings from the page allocator.


	Joerg

--
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/