[linux-next, x86_64] no backtrace after "printk/nmi: generic solution for safe printk in NMI"
From: Sergey Senozhatsky
Date: Thu Feb 25 2016 - 04:45:13 EST
seem that commit b927968830676373caf4241e80d8b447133f84b2
Author: Petr Mladek <pmladek@xxxxxxxx>
Date: Thu Feb 25 13:00:35 2016 +1100
printk/nmi: generic solution for safe printk in NMI
printk() takes some locks and could not be used a safe way in NMI context.
The chance of a deadlock is real especially when printing stacks from all
CPUs. This particular problem has been addressed on x86 by the commit
a9edc8809328 ("x86/nmi: Perform a safe NMI stack trace on all CPUs").
The patchset brings two big advantages. First, it makes the NMI
backtraces safe on all architectures for free. Second, it makes all NMI
messages almost safe on all architectures (the temporary buffer is
limited. We still should keep the number of messages in NMI context at
makes my x86_64 boxen unhappy, I see no CPU backtraces and no panic messages
on HARDLOCKUPs (CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE=1).
does it work for you?