[Xen-devel] Dom0 crash with old style AMD NUMA detection

[Andre Przywara <andre.przywara@xxxxxxx>]

Hi,

we see Dom0 crashes due to the kernel detecting the NUMA topology not by 
ACPI, but directly from the northbridge (CONFIG_AMD_NUMA).
This will detect the actual NUMA config of the physical machine, but 
will crash about the mismatch with Dom0's virtual memory. Variation of 
the theme: Dom0 sees what it's not supposed to see.
This happens with the said config option enabled and on a machine where 
this scanning is still enabled (K8 and Fam10h, not Bulldozer class)
We have this dump then:
[    0.000000] NUMA: Warning: node ids are out of bound, from=-1 to=-1
distance=10
[    0.000000] Scanning NUMA topology in Northbridge 24
[    0.000000] Number of physical nodes 4
[    0.000000] Node 0 MemBase 0000000000000000 Limit 0000000040000000
[    0.000000] Node 1 MemBase 0000000040000000 Limit 0000000138000000
[    0.000000] Node 2 MemBase 0000000138000000 Limit 00000001f8000000
[    0.000000] Node 3 MemBase 00000001f8000000 Limit 0000000238000000
[    0.000000] Initmem setup node 0 0000000000000000-0000000040000000
[    0.000000]   NODE_DATA [000000003ffd9000 - 000000003fffffff]
[    0.000000] Initmem setup node 1 0000000040000000-0000000138000000
[    0.000000]   NODE_DATA [0000000137fd9000 - 0000000137ffffff]
[    0.000000] Initmem setup node 2 0000000138000000-00000001f8000000
[    0.000000]   NODE_DATA [00000001f095e000 - 00000001f0984fff]
[    0.000000] Initmem setup node 3 00000001f8000000-0000000238000000
[    0.000000] Cannot find 159744 bytes in node 3
[    0.000000] BUG: unable to handle kernel NULL pointer dereference at 
(null)
[    0.000000] IP: [<ffffffff81d220e6>] __alloc_bootmem_node+0x43/0x96
[    0.000000] PGD 0
[    0.000000] Oops: 0000 [#1] SMP
[    0.000000] CPU 0
[    0.000000] Modules linked in:
[    0.000000]
[    0.000000] Pid: 0, comm: swapper Not tainted 3.3.6 #1 AMD Dinar/Dinar
[    0.000000] RIP: e030:[<ffffffff81d220e6>]  [<ffffffff81d220e6>] 
__alloc_bootmem_node+0x43/0x96
[    0.000000] RSP: e02b:ffffffff81c01de8  EFLAGS: 00010046
[    0.000000] RAX: 0000000000000000 RBX: 00000000000000c0 RCX: 
0000000000000000
[    0.000000] RDX: 0000000000000040 RSI: 00000000000000c0 RDI: 
0000000000000000
[    0.000000] RBP: ffffffff81c01e08 R08: 0000000000000000 R09: 
0000000000000000
[    0.000000] R10: 0000000000098000 R11: 0000000000000000 R12: 
0000000000000000
[    0.000000] R13: 0000000000000000 R14: 0000000000000040 R15: 
0000000000000003
[    0.000000] FS:  0000000000000000(0000) GS:ffffffff81ced000(0000) 
knlGS:0000000000000000
[    0.000000] CS:  e033 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.000000] CR2: 0000000000000000 CR3: 0000000001c05000 CR4: 
0000000000000660
[    0.000000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
0000000000000000
[    0.000000] DR3: 0000000000000000 DR6: 0000000000000000 DR7: 
0000000000000000
[    0.000000] Process swapper (pid: 0, threadinfo ffffffff81c00000, 
task ffffffff81c0d020)
[    0.000000] Stack:
[    0.000000]  00000000000000c0 0000000000000003 0000000000000000 
000000000000003f
[    0.000000]  ffffffff81c01e68 ffffffff81d23024 0000000000400000 
0000000000000002
[    0.000000]  0000000000080000 ffff8801f055e000 ffff8801f055e1f8 
0000000000000000
[    0.000000] Call Trace:
[    0.000000]  [<ffffffff81d23024>] 
sparse_early_usemaps_alloc_node+0x64/0x178
[    0.000000]  [<ffffffff81d23348>] sparse_init+0xe4/0x25a
[    0.000000]  [<ffffffff81d16840>] paging_init+0x13/0x22
[    0.000000]  [<ffffffff81d07fbb>] setup_arch+0x9c6/0xa9b
[    0.000000]  [<ffffffff81683954>] ? printk+0x3c/0x3e
[    0.000000]  [<ffffffff81d01a38>] start_kernel+0xe5/0x468
[    0.000000]  [<ffffffff81d012cf>] x86_64_start_reservations+0xba/0xc1
[    0.000000]  [<ffffffff81007153>] ? xen_setup_runstate_info+0x2c/0x36
[    0.000000]  [<ffffffff81d050ee>] xen_start_kernel+0x565/0x56c
[    0.000000] Code: 79 bc 3e ff 85 c0 74 23 80 3d 19 e9 21 00 00 75 59 
be 2a
01 00 00 48 c7 c7 d0 55 a8 81 e8 b6 dc 31 ff c6 05 ff e8 21 00 01 eb 3f 
<41> 8b
bc 24 60 60 02 00 49 83 c8 ff 4c 89 e9 4c 89 f2 48 89 de
[    0.000000] RIP  [<ffffffff81d220e6>] __alloc_bootmem_node+0x43/0x96
[    0.000000]  RSP <ffffffff81c01de8>
[    0.000000] CR2: 0000000000000000
[    0.000000] ---[ end trace a7919e7f17c0a725 ]---
[    0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
(XEN) Domain 0 crashed: 'noreboot' set - not rebooting.



The obvious solution would be to explicitly deny northbridge scanning 
when running as Dom0, though I am not sure how to implement this without 
upsetting the other kernel folks about "that crappy Xen thing" again ;-)
Could someone propose a fix for this (I am OoO for the next two weeks).

Regards,
Andre.

--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany


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