[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
On Tue, Jul 28, 2015 at 10:10 AM, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote: > On 07/28/2015 01:07 PM, Andy Lutomirski wrote: >> >> On Tue, Jul 28, 2015 at 9:30 AM, Andrew Cooper >> <andrew.cooper3@xxxxxxxxxx> wrote: >>> >>> I suspect that the set_ldt(NULL, 0) call hasn't reached Xen before >>> xen_free_ldt() is attempting to nab back the pages which Xen still has >>> mapped as an LDT. >>> >> I just instrumented it with yet more LSL instructions. I'm pretty >> sure that set_ldt really is clearing at least LDT entry zero. >> Nonetheless the free_ldt call still oopses. >> > > Yes, I added some instrumentation to the hypervisor and we definitely set > LDT to NULL before failing. > > -boris Looking at map_ldt_shadow_page: what keeps shadow_ldt_mapcnt from getting incremented once on each CPU at the same time if both CPUs fault in the same shadow LDT page at the same time? Similarly, what keeps both CPUs from calling get_page_type at the same time and therefore losing track of the page type reference count? I don't see why vmalloc or vm_unmap_aliases would have anything to do with this, though. --Andy -- Andy Lutomirski AMA Capital Management, LLC _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |