From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752925AbbAZLtt (ORCPT ); Mon, 26 Jan 2015 06:49:49 -0500 Received: from 8bytes.org ([81.169.241.247]:45922 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbbAZLtr (ORCPT ); Mon, 26 Jan 2015 06:49:47 -0500 Date: Mon, 26 Jan 2015 12:49:45 +0100 From: Joerg Roedel To: Borislav Petkov Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Konrad Rzeszutek Wilk , x86@kernel.org, linux-kernel@vger.kernel.org, Joerg Roedel Subject: Re: [PATCH 1/3] swiotlb: Warn on allocation failure in swiotlb_alloc_coherent Message-ID: <20150126114945.GD30345@8bytes.org> References: <1420555874-11506-1-git-send-email-joro@8bytes.org> <1420555874-11506-2-git-send-email-joro@8bytes.org> <20150123170425.GI22635@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150123170425.GI22635@pd.tnic> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 23, 2015 at 06:04:25PM +0100, Borislav Petkov wrote: > On Tue, Jan 06, 2015 at 03:51:12PM +0100, Joerg Roedel wrote: > > + > > +err_warn: > > + pr_warn("swiotlb: coherent allocation failed for device %s size=%zu\n", > > + dev_name(hwdev), size); > > + dump_stack(); > > Are we really sure we want to be that noisy about it? What happens if > that fails, we can't do DMA anymore or should we free some precious DMA > memory, as a compromise? Hmm, I don't think there is a way to request drivers to free DMA memory. What this patch does is to keep the same noisiness as before, just not from the page allocator but from the very end of the DMA allocation process, when everything failed. We can of course discuss whether this is too noisy and put some kind of ratelimit around. Joerg