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    intel-iommu: Free old page tables before creating superpage · 6491d4d0
    Woodhouse, David 提交于
    The dma_pte_free_pagetable() function will only free a page table page
    if it is asked to free the *entire* 2MiB range that it covers. So if a
    page table page was used for one or more small mappings, it's likely to
    end up still present in the page tables... but with no valid PTEs.
    
    This was fine when we'd only be repopulating it with 4KiB PTEs anyway
    but the same virtual address range can end up being reused for a
    *large-page* mapping. And in that case were were trying to insert the
    large page into the second-level page table, and getting a complaint
    from the sanity check in __domain_mapping() because there was already a
    corresponding entry. This was *relatively* harmless; it led to a memory
    leak of the old page table page, but no other ill-effects.
    
    Fix it by calling dma_pte_clear_range (hopefully redundant) and
    dma_pte_free_pagetable() before setting up the new large page.
    Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
    Tested-by: NRavi Murty <Ravi.Murty@intel.com>
    Tested-by: NSudeep Dutt <sudeep.dutt@intel.com>
    Cc: stable@kernel.org [3.0+]
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    6491d4d0
intel-iommu.c 106.8 KB