We need to switch to emergency printk mode in kernel_kexec(). One kernel_kexec() branch calls kernel_restart_prepare(), which updates `system_state', however, the other one, when user requested to ->preserve_context, does not and we are lacking the information in printk about kexec being executed. Register a syscore notifier so printk will be notified by syscore_suspend().
Signed-off-by: Sergey Senozhatsky <[email protected]> --- kernel/printk/printk.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 5b2b97ee3440..4e5233a265cb 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -51,6 +51,7 @@ #include <linux/kthread.h> #include <linux/smpboot.h> #include <linux/suspend.h> +#include <linux/syscore_ops.h> #include <linux/uaccess.h> #include <asm/sections.h> @@ -2970,6 +2971,22 @@ static struct notifier_block printk_pm_nb = { .notifier_call = printk_pm_notify, }; +static int printk_pm_syscore_suspend(void) +{ + printk_emergency_begin(); + return 0; +} + +static void printk_pm_syscore_resume(void) +{ + printk_emergency_end(); +} + +static struct syscore_ops printk_pm_syscore_ops = { + .suspend = printk_pm_syscore_suspend, + .resume = printk_pm_syscore_resume, +}; + static void printk_kthread_func(unsigned int cpu) { while (1) { @@ -3027,6 +3044,7 @@ static int __init init_printk_kthreads(void) return -EINVAL; } + register_syscore_ops(&printk_pm_syscore_ops); return 0; } late_initcall(init_printk_kthreads); -- 2.13.0
