It might take ages until users see messages from NMI context. They cannot be flushed to the console because the operation involves taking and releasing a bunch of locks. Everything gets fixed by the followup printk in normal context but it is not predictable.
The same problem has printk_sched() and this patch reuses the existing solution. There is no special printk() variant for NMI context. Hence the IRQ work need to get queued from vprintk_emit(). Signed-off-by: Petr Mladek <[email protected]> --- kernel/printk/printk.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index bf2abdda5869..c2ae9ff388ae 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1554,9 +1554,6 @@ int printk_deferred(const char *fmt, ...) va_start(args, fmt); r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); va_end(args); - - __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); - irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); preempt_enable(); return r; @@ -1880,7 +1877,10 @@ asmlinkage int vprintk_emit(int facility, int level, * If called from the scheduler or NMI context, we can not get console * without a possible deadlock. */ - if (!in_sched && !in_nmi()) { + if (in_sched || in_nmi()) { + __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); + irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); + } else { lockdep_off(); /* * Disable preemption to avoid being preempted while holding -- 1.8.5.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
