[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH]: Better checking in range_straddles_page_boundary
On 22/10/08 10:05, "Chris Lalancette" <clalance@xxxxxxxxxx> wrote: > Attached is a simple patch to slightly rework the logic in > range_straddles_page_boundary(). The reason for this is to avoid a crash we > are > seeing on 32-bit dom0. Basically, the contiguous_bitmap is allocated based on > max_low_pfn. However, the swiotlb code can be passed a request (in > swiotlb_map_sg) that is > 1 page (I've seen 2 pages), and is also a page > (sg->page) > max_low_pfn. If this combination happens, then you get a fatal > page fault when doing the test_bit(pfn, contiguous_bitmap). For that reason, > rework the logic in range_straddles_page_boundary so that if it gets a request > > > 1 page, and it's above max_low_pfn, then we force the splitting of the > request. > In our testing, this seems to fix the issue. How about we just get rid of the contiguous_bitmap? We might as well if you are going to push that check after calling check_pages_physically_contiguous(), since no extent which is acceptable to contiguous_bitmap should fail on check_pages_physically_contiguous(). I think I kept contiguous_bitmap only as a fast check before calling that slower function. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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