[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Kernel bug from 3.0 (was phy disks and vifs timing out in DomU)
On 26/08/11 15:44, Konrad Rzeszutek Wilk wrote: > > So while I am still looking at the hypervisor code to figure out why > it would give me [when trying to map a grant page]: > > (XEN) mm.c:3846:d0 Could not find L1 PTE for address fbb42000 It is failing in guest_map_l1e() because the page for the vmalloc'd virtual address PTEs is not present. The test that fails is: (l2e_get_flags(l2e) & (_PAGE_PRESENT | _PAGE_PSE)) != _PAGE_PRESENT I think this is because the GNTTABOP_map_grant_ref hypercall is done when task->active_mm != &init_mm and alloc_vm_area() only adds PTEs into init_mm so when Xen looks in the page tables it doesn't find the entries because they're not there yet. Putting a call to vmalloc_sync_all() after create_vm_area() and before the hypercall makes it work for me. Classic Xen kernels used to have such a call. This presumably works on some systems/configuration and not others depending on what else is using vmalloc(). i.e., if another kernel thread (?) calls vmalloc() etc. then there will be a page for vmalloc area PTEs and it will work. I'll try and post a patch tomorrow. Thanks to Ian Campbell for pointing me in the right direction. David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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