On Wed 2018-05-23 11:01:07, Sergey Senozhatsky wrote: > On (05/22/18 17:43), Steven Rostedt wrote: > > > CPU0 CPU1 CPU2 > > > > > > printk() > > > vprintk_emit() > > > spin_lock(&logbuf_lock) > > > > > > trigger_all_cpu_backtrace() > > > raise() > > > > > > nmi_enter() > > > printk_nmi_enter() > > > if (this_cpu_read(printk_context) > > > & PRINTK_SAFE_CONTEXT_MASK) > > > // false > > > else > > > // looks safe to use printk_deferred() > > > this_cpu_or(printk_context, > > > PRINTK_NMI_DEFERRED_CONTEXT_MASK); > > > > > > nmi_cpu_backtrace() > > > arch_spin_lock(&lock); > > > > What branch is this based on, because I can't find the > > "arch_spin_lock()" you are talking about here. > > This arch_spin_lock() is in lib/nmi_backtrace.c > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/nmi_backtrace.c?h=v4.17-rc6#n94 JFYI, I have pushed the patch into printk.git, for-4.18 branch, see https://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk.git/commit/?h=for-4.18&id=42f139d887cbb2c396dd61f4f13d4facfde5739e Best Regards, Petr
