Re: [PATCH] kernel/watchdog: flush all printk nmi buffers when hardlockup detected

[Sergey Senozhatsky]

On (20/02/10 12:48), Konstantin Khlebnikov wrote:
> 
> In NMI context printk() could save messages into per-cpu buffers and
> schedule flush by irq_work when IRQ are unblocked. This means message
> about hardlockup appears in kernel log only when/if lockup is gone.
> 
> Comment in irq_work_queue_on() states that remote IPI aren't NMI safe
> thus printk() cannot schedule flush work to another cpu.
> 
> This patch adds simple atomic counter of detected hardlockups and
> flushes all per-cpu printk buffers in context softlockup watchdog
> at any other cpu when it sees changes of this counter.

Petr, could you remind me, why do we do PRINTK_NMI_DIRECT_CONTEXT_MASK
only from ftrace?

	-ss