Messages in this thread |  | | Date | Tue, 5 Feb 2013 14:31:05 +0100 | From | Joerg Roedel <> | Subject | Re: IO_PAGE_FAULTs on unity mapped regions during amd_iommu_init() in Linux 3.4 |
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Hi Shuah,
On Fri, Feb 01, 2013 at 11:31:59AM -0700, Shuah Khan wrote: > Yes, 3.7 has the same window of opportunity for this race condition, > however I couldn't figure out why it doesn't happen on 3.7. On 3.7 the > window between amd_iommu_init_hardware() and amd_iommu_init_dma_ops() > might actually be wider than the window in 3.4.
I think this is highly timing related. IOMMU initialization may have been moved by a few milliseconds between the kernel versions which might cause the warnings to appear or disappear. I don't think it has much value to dive deeper into the differences between the initialization sequences.
As somethimes with such issues there is a simple and a more complex fix for that. I'll try to come up with a simple fix for the next merge window and implement the clean and more complex one for the next one.
Joerg
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