4.18.y build failure

The following commit in 4.18.y causes the build to fail: 79764192e1c4 ("printk/nmi: Prevent deadlock when accessing the main log buffer in NMI")

with: | kernel/printk/printk_safe.o: In function `vprintk_func': | printk_safe.c:(.text+0x51b): undefined reference to `vprintk_store' | printk_safe.c:(.text+0x52f): undefined reference to `defer_console_output'

Picking up these from mainline seems to do the trick: a338f84dc196 ("printk: Create helper function to queue deferred console handling") ba552399954d ("printk: Split the code for storing a message into the log buffer")

Thanks, Dan