Messages in this thread | | | From | Sheng Yang <> | Subject | Re: Crash in intel_iommu_assign_device | Date | Tue, 2 Nov 2010 14:52:19 +0800 |
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On Monday 01 November 2010 19:41:21 Jan Kiszka wrote: > Hi Sheng, > > I'm not claiming to understand the details, but this looks like use > (dereference of pte via dma_pte_addr) after release (free_pgtable_page > of dmar_domain->pgd aka pte) to me: > > static int intel_iommu_attach_device(struct iommu_domain *domain, > struct device *dev) > { > [...] > pte = dmar_domain->pgd; > if (dma_pte_present(pte)) { > free_pgtable_page(dmar_domain->pgd); > dmar_domain->pgd = (struct dma_pte *) > phys_to_virt(dma_pte_addr(pte)); > } > > At least it crashes here right on pte->val access. Swap both lines?
I think code is right.
The comment above indicate the case: the code want to decrease the level of page table. Mostly it is a 4 level page table, and the code would turn it into 3 levels pagetable. What the code did is just get the first entry of the old pagetable level 4, then free the level 4 pagetable's page, and make the pagetable to a level 3 pagetable.
Seems it make no sense to swap the lines...
-- regards Yang, Sheng
> > Jan
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