On 06/20/2014 04:29 PM, Borislav Petkov wrote:
On Fri, Jun 20, 2014 at 04:16:50PM -0400, Boris Ostrovsky wrote:
Sorry, mce_device_create().
We can't call it in the notifier until mcheck_init_device() has been
successfully executed (we need subsys_system_register(&mce_subsys)). I don't
know whether we can call subsys_system_register() in mcheck_init() -- it is
quite early in the boot.
I don't think it matters: we want to add only this oneliner to
mcheck_init():
__register_hotcpu_notifier(&mce_cpu_notifier);
and remove it from mcheck_init_device(), nothing else. And we don't need
the synchronization even because we're BSP only then.
I mean, we won't be able to offline CPUs that early anyway - thus
call mce_device_create() in the notifier callback - as we don't have
userspace to do "echo 0 > ..."
The rest of the code remains and mcheck_init_device() executes when it
does. Unless I'm missing something, of course...
We are getting CPU_ONLINE notifier for ASPs during boot:
[ 14.489595] cpu 1 spinlock event irq 48
[ 14.502908] BUG: unable to handle kernel NULL pointer dereference at
0000000000000060
[ 14.527373] IP: [<ffffffff8144deec>] bus_add_device+0xfc/0x1e0
[ 14.545859] PGD 0
[ 14.552380] Oops: 0000 [#1] SMP
[ 14.562711] Modules linked in:
[ 14.572494] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
3.16.0-rc1-pmu-dom0 #195
[ 14.595307] Hardware name: Intel Corporation Shark Bay Client
platform/Flathead Creek Crb, BIOS HSWLPTU1.86C.0109.R03.1301282055
01/28/2013
[ 14.634718] task: ffff88022f5a0000 ti: ffff88022f53c000 task.ti:
ffff88022f53c000
[ 14.658364] RIP: e030:[<ffffffff8144deec>] [<ffffffff8144deec>]
bus_add_device+0xfc/0x1e0
[ 14.684457] RSP: e02b:ffff88022f53fc68 EFLAGS: 00010246
[ 14.701310] RAX: 0000000000000000 RBX: ffff88023d411810 RCX:
00000000d7c6bb9d
[ 14.723875] RDX: ffff88023d402a60 RSI: ffff88023d411810 RDI:
ffff88023d411810
[ 14.746427] RBP: ffff88022f53fc98 R08: 0000000000000000 R09:
0000000000000000
[ 14.768962] R10: ffffffff8133bbc0 R11: ffffea0008bd9600 R12:
ffff88023d411800
[ 14.791522] R13: ffffffff81c284b8 R14: ffffffff81c284a0 R15:
0000000000000000
[ 14.814087] FS: 0000000000000000(0000) GS:ffff88023da00000(0000)
knlGS:0000000000000000
[ 14.839632] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 14.857845] CR2: 0000000000000060 CR3: 0000000001c10000 CR4:
0000000000042660
[ 14.880413] Stack:
[ 14.886913] ffff88023d411800 ffff88023d411800 0000000000000000
0000000000000000
[ 14.910293] ffff88023d411810 0000000000000000 ffff88022f53fcf8
ffffffff8144be3f
[ 14.933692] 00000000fffffffb 0000000000000000 ffff88022f53fcd8
ffffffff81459c85
[ 14.957075] Call Trace:
[ 14.964971] [<ffffffff8144be3f>] device_add+0x43f/0x5e0
[ 14.981809] [<ffffffff81459c85>] ? pm_runtime_init+0xe5/0xf0
[ 15.000014] [<ffffffff8144c1be>] device_register+0x1e/0x30
[ 15.017697] [<ffffffff8103b04c>] mce_device_create+0x7c/0x1c0
[ 15.036168] [<ffffffff8103b2a8>] mce_cpu_callback+0x118/0x140
[ 15.054636] [<ffffffff810abb3d>] notifier_call_chain+0x4d/0x70
[ 15.073371] [<ffffffff810abc4e>] __raw_notifier_call_chain+0xe/0x10
[ 15.093466] [<ffffffff81085460>] __cpu_notify+0x20/0x40
[ 15.110321] [<ffffffff81085495>] cpu_notify+0x15/0x20
[ 15.126613] [<ffffffff81085767>] _cpu_up+0x107/0x160
[ 15.142649] [<ffffffff81085819>] cpu_up+0x59/0x80
[ 15.157870] [<ffffffff81d46fdf>] smp_init+0x60/0x8c
[ 15.173620] [<ffffffff81d2616a>] kernel_init_freeable+0xfa/0x20d
[ 15.192908] [<ffffffff8100332e>] ? xen_end_context_switch+0x1e/0x30
[ 15.213023] [<ffffffff816aecf0>] ? rest_init+0x80/0x80
[ 15.229592] [<ffffffff816aecfe>] kernel_init+0xe/0xf0
[ 15.245904] [<ffffffff816c0ebc>] ret_from_fork+0x7c/0xb0
[ 15.263034] [<ffffffff816aecf0>] ? rest_init+0x80/0x80
[ 15.279607] Code: d2 ff ff 85 c0 41 89 c7 0f 85 88 00 00 00 49 8b 54
24 50 48 85 d2 0f 84 93 00 00 00 49 8b 86 90 00 00 00 49 8d 5c 24 10 48
89 de <48> 8b 78 60 48 83 c7 18 e8 c7 00 e0 ff 85 c0 41 89 c7 74 10 4c
[ 15.338846] RIP [<ffffffff8144deec>] bus_add_device+0xfc/0x1e0
[ 15.357605] RSP <ffff88022f53fc68>
[ 15.368729] CR2: 0000000000000060
[ 15.379338] ---[ end trace d288f65f5999f472 ]---
[ 15.394005] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x00000009
-boris
Oh, not quite. We probably should remove the
__unregister_hotcpu_notifier(&mce_cpu_notifier);
from the error path too, as you suggest.
When you do, please hold that down in the commit message so that it is
clear what we're doing.
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