[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] grant table interface addition?
>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 03.11.08 13:55 >>> >On 3/11/08 12:13, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote: > >> While looking in more detail into how all this fits together, I realized that >> there appears to be a race condition in blktap: Since fast_flush_area() >> and dispatch_rw_block_io() call create_lookup_pte_addr() without holding >> mm->mmap_sem, there's nothing preventing the just verified (or >> created) page table structures to go away again before >> HYPERVISOR_grant_table_op() is able to finish (or even begin) its job. >> Am I missing something here? > >So, for example, it could be munmap()ed under those functions' feet? Or the >process could die? Looks like you could be right, although I've never looked >closely at the blktap kernel driver. Process death is probably not a concern, but munmap() of the region in question or (potentially, maybe not in current kernels) even a nearby one is. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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