Dan Magenheimer
2010-Mar-27 16:29 UTC
[Xen-devel] Strange vcpu count on forced domain crash
This is likely not a bug, but I know there''s been some work in hotplug CPU support lately, so I thought I''d report this on the chance that it is a bug: For benchmarking purposes (to stop a guest immediately and leave it in a crashed state), I use: # echo c > /proc/sysrq-trigger in the (PV) guest. I''ve noticed that when I do this on a vcpus==2 PV guest, the "xm list" then shows it as vcpus==1, while xentop continues to report it as vcpus==2. When this happens, I often get a flurry of Xen messages from memory.c and/or page_alloc.c, of the type: (XEN) page_alloc.c:1083:d6 Over-allocation for domain 6: 131073 > 131072 (XEN) memory.c:132:d6 Could not allocate order=0 extent: id=6 memflags=0 (0 of 5 12) though at other times I''ve also seen a bunch of: (XEN) mm.c:3798:d3 Bad donate 0000000000067a90: ed=ffff830069140000(3), sd=00000 00000000000, caf=8000000000000001, taf=0000000000000000 and once a crash with: (XEN) mm.c:2363:d0 Bad type (saw 7400000001000000 != exp 1000000000000000) for m fn 7af88 (pfn c78) (XEN) mm.c:867:d0 Attempt to create linear p.t. with write perms (XEN) mm.c:1329:d0 Failure in alloc_l2_table: entry 64 (XEN) mm.c:2116:d0 Error while validating mfn 70326 (pfn 56d9) for type 20000000 00000000: caf=8000000000000003 taf=2000000000000001 (XEN) mm.c:1439:d0 Failure in alloc_l3_table: entry 0 (XEN) mm.c:2116:d0 Error while validating mfn 74f0f (pfn a2f0) for type 30000000 00000000: caf=8000000000000003 taf=3000000000000001 (XEN) mm.c:2731:d0 Error while pinning mfn 74f0f For awhile, since I was doing tmem testing, I thought this was a tmem problem, but I just reproduced it (the first mm.c error message anyway) with tmem disabled, though the PV guest IS doing self-ballooning. I''m not sure if this behavior was the same in previous Xen releases or if this is new behavior. I''ve only seen any of this after running a test for many hours... I tried reproducing it with a shorter similar test but without luck. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel