From: Catalin Marinas <catalin.marinas@arm.com>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Qian Cai <cai@lca.pw>,
f.fainelli@gmail.com, mbrugger@suse.com, marc.zyngier@arm.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, Rob Herring <robh+dt@kernel.org>,
linux-rpi-kernel@lists.infradead.org, m.szyprowski@samsung.com,
Robin Murphy <Robin.Murphy@arm.com>,
phill@raspberrypi.org, will@kernel.org,
Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org, wahrenst@gmx.net
Subject: Re: [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32
Date: Thu, 31 Oct 2019 15:51:45 +0000 [thread overview]
Message-ID: <20191031155145.GF39590@arrakis.emea.arm.com> (raw)
In-Reply-To: <1956a2c8f4911b2a7e2ba3c53506c0f06efb93f8.camel@suse.de>
(sorry, I've been away last week and only now caught up with emails)
On Tue, Oct 22, 2019 at 01:23:32PM +0200, Nicolas Saenz Julienne wrote:
> On Mon, 2019-10-21 at 16:36 -0400, Qian Cai wrote:
> > I managed to get more information here,
> >
> > [ 0.000000] cma: dma_contiguous_reserve(limit c0000000)
> > [ 0.000000] cma: dma_contiguous_reserve: reserving 64 MiB for global area
> > [ 0.000000] cma: cma_declare_contiguous(size 0x0000000004000000, base
> > 0x0000000000000000, limit 0x00000000c0000000 alignment 0x0000000000000000)
> > [ 0.000000] cma: Failed to reserve 512 MiB
> >
> > Full dmesg:
> >
> > https://cailca.github.io/files/dmesg.txt
>
> OK I got it, reproduced it too.
>
> Here are the relevant logs:
>
> [ 0.000000] DMA [mem 0x00000000802f0000-0x00000000bfffffff]
> [ 0.000000] DMA32 [mem 0x00000000c0000000-0x00000000ffffffff]
> [ 0.000000] Normal [mem 0x0000000100000000-0x00000097fcffffff]
>
> As you can see ZONE_DMA spans from 0x00000000802f0000-0x00000000bfffffff which
> is slightly smaller than 1GB.
>
> [ 0.000000] crashkernel reserved: 0x000000009fe00000 - 0x00000000bfe00000 (512 MB)
>
> Here crashkernel reserved 512M in ZONE_DMA.
>
> [ 0.000000] cma: Failed to reserve 512 MiB
>
> CMA tried to allocate 512M in ZONE_DMA which fails as there is no enough space.
> Makes sense.
>
> A fix could be moving crashkernel reservations after CMA and then if unable to
> fit in ZONE_DMA try ZONE_DMA32 before bailing out. Maybe it's a little over the
> top, yet although most devices will be fine with ZONE_DMA32, the RPi4 needs
> crashkernel to be reserved in ZONE_DMA.
Does RPi4 need CMA in ZONE_DMA? If not, I'd rather reserve the CMA from
ZONE_DMA32.
Even if you moved the crash kernel, someone else might complain that
they had 2GB of CMA and it no longer works.
--
Catalin
next prev parent reply other threads:[~2019-10-31 15:51 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 18:25 [PATCH v6 0/4] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-09-11 18:25 ` [PATCH v6 1/4] arm64: mm: use arm64_dma_phys_limit instead of calling max_zone_dma_phys() Nicolas Saenz Julienne
2019-09-11 18:25 ` [PATCH v6 2/4] arm64: rename variables used to calculate ZONE_DMA32's size Nicolas Saenz Julienne
2019-09-11 18:25 ` [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32 Nicolas Saenz Julienne
2019-10-21 14:15 ` Qian Cai
2019-10-21 14:34 ` Nicolas Saenz Julienne
2019-10-21 14:46 ` Qian Cai
2019-10-21 17:01 ` Nicolas Saenz Julienne
2019-10-21 17:25 ` Qian Cai
2019-10-21 17:55 ` Nicolas Saenz Julienne
2019-10-21 20:36 ` Qian Cai
2019-10-22 11:23 ` Nicolas Saenz Julienne
2019-10-23 7:11 ` Matthias Brugger
2019-10-31 15:51 ` Catalin Marinas [this message]
2019-10-31 16:04 ` Nicolas Saenz Julienne
2019-10-31 18:02 ` Catalin Marinas
2019-10-31 18:11 ` Nicolas Saenz Julienne
2019-10-31 18:13 ` Catalin Marinas
2019-12-03 5:08 ` John Stultz
2019-12-03 5:38 ` John Stultz
2019-12-03 6:03 ` John Stultz
2019-12-03 10:12 ` Will Deacon
2019-12-03 11:19 ` Catalin Marinas
2019-09-11 18:25 ` [PATCH v6 4/4] mm: refresh ZONE_DMA and ZONE_DMA32 comments in 'enum zone_type' Nicolas Saenz Julienne
2019-10-01 16:05 ` [PATCH v6 0/4] Raspberry Pi 4 DMA addressing support Catalin Marinas
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