2014-04-29 19:27 GMT+08:00 Petr Tesarik <ptesarik@xxxxxxx>:
It will show an incorrect register dump, but the backtrace continues.
For example:
Hi Petr,
The back trace looks good.
How did you know the register dump is incorrect?
At least the value of RSP saved in NMI stack seemed to be good,
RSP: ffff880232b2ff18
Recently, I'm working on a core file analysis, and found crash tool couldn't give the correct NMI back trace.
But I can find right stack trace by using IST pointer.
I'm wondering whether your patch could work for my cases.
May I can try your fix after it is ready.
PID: 0 TASK: ffff880232b2c440 CPU: 7 COMMAND: "kworker/0:1"
#0 [ffff88023fdc7e40] crash_nmi_callback at ffffffff8102428f
#1 [ffff88023fdc7e50] notifier_call_chain at ffffffff81461ec7
#2 [ffff88023fdc7e80] __atomic_notifier_call_chain at ffffffff81461f0d
#3 [ffff88023fdc7e90] notify_die at ffffffff81461f5d
#4 [ffff88023fdc7ec0] default_do_nmi at ffffffff8145f3a7
#5 [ffff88023fdc7ee0] do_nmi at ffffffff8145f5d8
#6 [ffff88023fdc7ef0] restart_nmi at ffffffff8145eb2d
[exception RIP: mwait_idle+423]
RIP: ffffffff8100b217 RSP: ffff880232b2ff18 RFLAGS: 00000246
RAX: 0000000000000010 RBX: 0000000000000010 RCX: 0000000000000246
RDX: ffff880232b2ff18 RSI: 0000000000000018 RDI: 0000000000000001
RBP: ffffffff8100b217 R8: ffffffff8100b217 R9: 0000000000000018
R10: ffff880232b2ff18 R11: 0000000000000246 R12: ffffffffffffffff
R13: ffffffff81d36108 R14: ffff880232b2ffd8 R15: 0000000000000000
ORIG_RAX: 0000000000000000 CS: 0010 SS: 0018
--- <NMI exception stack> ---
#7 [ffff880232b2ff18] mwait_idle at ffffffff8100b217
#8 [ffff880232b2ff30] cpu_idle at ffffffff81002126
If there is a nested NMI, reading the code suggests crash may loop again to the NMI stack, but I don't have a sample dump file ATM.
Petr T
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Oliver Yang
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