linux-kernel - Re: DMA-API: cacheline tracking ENOMEM, dma-debug disabled due to nouveau ?

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]

Date:   Thu, 15 Aug 2019 15:35:54 +0200
From:   Christoph Hellwig <hch@....de>
To:     Corentin Labbe <clabbe.montjoie@...il.com>, bskeggs@...hat.com,
        airlied@...ux.ie, hch@....de, m.szyprowski@...sung.com,
        robin.murphy@....com, dri-devel@...ts.freedesktop.org,
        nouveau@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org
Subject: Re: DMA-API: cacheline tracking ENOMEM, dma-debug disabled due to
 nouveau ?

On Wed, Aug 14, 2019 at 07:49:27PM +0200, Daniel Vetter wrote:
> On Wed, Aug 14, 2019 at 04:50:33PM +0200, Corentin Labbe wrote:
> > Hello
> > 
> > Since lot of release (at least since 4.19), I hit the following error message:
> > DMA-API: cacheline tracking ENOMEM, dma-debug disabled
> > 
> > After hitting that, I try to check who is creating so many DMA mapping and see:
> > cat /sys/kernel/debug/dma-api/dump | cut -d' ' -f2 | sort | uniq -c
> >       6 ahci
> >     257 e1000e
> >       6 ehci-pci
> >    5891 nouveau
> >      24 uhci_hcd
> > 
> > Does nouveau having this high number of DMA mapping is normal ?
> 
> Yeah seems perfectly fine for a gpu.

That is a lot and apparently overwhelm the dma-debug tracking.  Robin
rewrote this code in Linux 4.21 to work a little better, so I'm curious
why this might have changes in 4.19, as dma-debug did not change at
all there.