Offload printing of printk_deferred() messages from IRQ context to a schedulable printing kthread, when possible (the same way we do it in vprintk_emit()). Otherwise, console_unlock() can force the printing CPU to spend unbound amount of time flushing kernel messages from IRQ context.
Signed-off-by: Sergey Senozhatsky <[email protected]> --- kernel/printk/printk.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index ab6b3b2a68c6..1927b5cb5cbe 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2741,8 +2741,16 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work) * If trylock fails, someone else is doing the printing. * PRINTK_PENDING_OUTPUT bit is cleared by console_unlock(). */ - if (console_trylock()) - console_unlock(); + if (printk_kthread_enabled()) { + wake_up_process(printk_kthread); + } else { + /* + * If trylock fails, someone else is doing the + * printing + */ + if (console_trylock()) + console_unlock(); + } } if (test_and_clear_bit(PRINTK_PENDING_WAKEUP, &printk_pending)) -- 2.12.2
