[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] GNTTABOP_unmap_grant_ref
Mark & All, Short version: If a domU driver provides an application with a mapping to a shared page, where in the driver should the corresponding GNTTABOP_unmap_grant_ref call reside to avoid a domain crash? Long version: I'm trying fix my code running in a domU to avoid Xen calling domain_crash() in mm.c line 615. This occurs when a domain "implicitly unmaps a granted PTE". The somewhat abridged version of events: 1) Remote domU shares a page 2) app in local domU calls mmap() 3) driver mmap code calls GNTTAB_map_grant_ref() and returns the mapping to the app 4) app accesses the shared page without problem 5) app is done, calls munmap() 6) Xen kills the domain in mm.c line 615. I have not yet found a way to make the GNTTABOP_unmap_grant_ref() call in time to avoid the crash. The driver release() function is too late and there's no hook in struct file_operations to handle unmap explicitly. Mark Williamson's blktap driver is calling GNTTAB_unmap_grant_ref, but it's unclear to me if the same unmap()'ing problem exists there too. Any help is much appreciated. -steve _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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