From: Catalin Marinas <catalin.marinas@arm.com> To: Will Deacon <will@kernel.org> Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, Amit Pundir <amit.pundir@linaro.org>, Florian Fainelli <f.fainelli@gmail.com>, mbrugger@suse.com, Marc Zyngier <marc.zyngier@arm.com>, lkml <linux-kernel@vger.kernel.org>, Bjorn Andersson <bjorn.andersson@linaro.org>, linux-mm <linux-mm@kvack.org>, Rob Herring <robh+dt@kernel.org>, John Stultz <john.stultz@linaro.org>, wahrenst@gmx.net, Nicolas Dechense <nicolas.dechesne@linaro.org>, Marek Szyprowski <m.szyprowski@samsung.com>, Robin Murphy <robin.murphy@arm.com>, Christoph Hellwig <hch@lst.de>, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>, linux-rpi-kernel@lists.infradead.org Subject: Re: [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32 Date: Tue, 3 Dec 2019 11:19:00 +0000 Message-ID: <20191203111900.GA23522@arrakis.emea.arm.com> (raw) In-Reply-To: <20191203101249.GC6815@willie-the-truck> On Tue, Dec 03, 2019 at 10:12:50AM +0000, Will Deacon wrote: > On Mon, Dec 02, 2019 at 10:03:17PM -0800, John Stultz wrote: > > Ok, narrowing it down further, it seems its the following bit from the > > patch: > > > > > @@ -201,13 +212,18 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > > > struct memblock_region *reg; > > > unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES]; > > > unsigned long max_dma32 = min; > > > + unsigned long max_dma = min; > > > > > > memset(zone_size, 0, sizeof(zone_size)); > > > > > > - /* 4GB maximum for 32-bit only capable devices */ > > > +#ifdef CONFIG_ZONE_DMA > > > + max_dma = PFN_DOWN(arm64_dma_phys_limit); > > > + zone_size[ZONE_DMA] = max_dma - min; > > > + max_dma32 = max_dma; > > > +#endif > > > #ifdef CONFIG_ZONE_DMA32 > > > max_dma32 = PFN_DOWN(arm64_dma32_phys_limit); > > > - zone_size[ZONE_DMA32] = max_dma32 - min; > > > + zone_size[ZONE_DMA32] = max_dma32 - max_dma; > > > #endif > > > zone_size[ZONE_NORMAL] = max - max_dma32; > > > > > > @@ -219,11 +235,17 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > > > > > > if (start >= max) > > > continue; > > > - > > > +#ifdef CONFIG_ZONE_DMA > > > + if (start < max_dma) { > > > + unsigned long dma_end = min_not_zero(end, max_dma); > > > + zhole_size[ZONE_DMA] -= dma_end - start; > > > + } > > > +#endif > > > #ifdef CONFIG_ZONE_DMA32 > > > if (start < max_dma32) { > > > - unsigned long dma_end = min(end, max_dma32); > > > - zhole_size[ZONE_DMA32] -= dma_end - start; > > > + unsigned long dma32_end = min(end, max_dma32); > > > + unsigned long dma32_start = max(start, max_dma); > > > + zhole_size[ZONE_DMA32] -= dma32_end - dma32_start; > > > } > > > #endif > > > if (end > max_dma32) { > > > > The zhole_sizes end up being: > > zhole_size: DMA: 67671, DMA32: 1145664 NORMAL: 0 > > > > This seems to be due to dma32_start being calculated as 786432 each > > time - I'm guessing that's the max_dma value. > > Where dma32_end is around 548800, but changes each iteration (so we > > end up subtracting a negative value each pass, growing the size). [...] > Anyway, I've had a go at fixing it below but it's 100% untested. I think > the issue is that your SoC has memblocks contained entirely within the > ZONE_DMA region and we don't cater for that at all when processing the > ZONE_DMA32 region. This seems to be issue, the SoC memory contained withing ZONE_DMA. I managed to reproduce it under KVM/Qemu by reducing the amount of memory given to the guest. You'd also need NUMA disabled to hit this code path. Your proposed change fixes it but I'll send a tested-by on the full patch when it hits the list. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply index 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 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 [this message] 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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