Messages in this thread | | | Date | Tue, 15 Dec 2009 18:23:08 +0900 | Subject | Re: bisected crash due to "x86: Move swiotlb initialization before dma32_free_bootmem" | From | FUJITA Tomonori <> |
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On Tue, 15 Dec 2009 01:11:05 -0800 Yinghai Lu <yinghai@kernel.org> wrote:
> FUJITA Tomonori wrote: > > On Mon, 14 Dec 2009 23:47:07 -0800 > > Roland Dreier <rdreier@cisco.com> wrote: > > > >> I have a big box (64 threads, 256GB memory) that is crashing early in > >> boot as below. I bisected it down to f4780ca0 ("x86: Move swiotlb > >> initialization before dma32_free_bootmem"); reverting just this commit > >> from the latest git (3ea6b3d0 is what I tested) fixes things. > > > > Ah, really sorry about that. > > > > > >> I haven't tried to debug this yet, but I guess on such a huge box there > >> is not enough memory below 4GB for swiotlb if we don't free the > > > > Yeah, Yinghai also hit this (his box has more memory than yours). > > > > > >> stuff allocated earlier? I don't know why that would be, since the > >> bootmem is grabbing 512MB and I have pretty close to 4GB below 4GB. > >> Anyway, I'm going to go to bed soon, but if you need more information or > >> have anything you want me to try, I will do it tomorrow morning. > > > > http://www.kernel.org/pub/linux/kernel/people/tomo/misc/0001-x86-two-stage-swiotlb-initialization.patch > > > > It makes the swiotlb initialization into two stages. I don't like it > > much since I like to avoid complicating the initialization. > > > > dma32_reserve_bootmem() allocates 128MB for broken GART IOMMU but I > > think 64MB should be enough since broken GART IOMMU allocates > > 64MB. The following simple patch might work too because swiotlb uses > > 64MB. > > > > With coming huge memory boxes, we might need to work on ZONE_DMA32 > > shortage issue anyway (sparse-vmemmap, anything else)? > > maybe just revert f4780ca0... for now
As I wrote, I think that the following patch works.
http://www.kernel.org/pub/linux/kernel/people/tomo/misc/0001-x86-two-stage-swiotlb-initialization.patch
There are a few people who hit this. How many people use a box with over 256GB memory?
And you can work around this with "dma32_size" kernel boot option.
> actually dma32_free_bootmem will also make sure it will give some buffer to pci_swiotlb_init...
But unlike broken GART BIOS, swiotlb doesn't set the goal. swiotlb had been fine without dma32_reserve_bootmem(). We use more DMA32_ZONE than we did though.
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