Commit 5f339c46f153 for kernel

commit 5f339c46f153184570f16c8e789c9709b14cbe8b
Author: John Ogness <john.ogness@linutronix.de>
Date:   Fri Oct 16 11:00:34 2026 +0206

    printk: Postpone kthread startup

    There have been various bug reports related to SMP systems hanging
    on boot. The reports vary but seem to have some overlap with regard
    to missed IPI's during SMP setup. The reports also show that
    reverting NBCON console usage allows the bugs to disappear.

    The NBCON kthreads for console printing are started very early
    during boot using early_initcall(). Since these kthreads are
    asynchronously enabling/disabling interrupts during early boot, they
    may be interfering with early SMP setup on some hardware platforms.

    Starting the console printing kthreads later has shown to avoid the
    hanging on systems that could previously reproduce the issue.

    Postpone kthread starting until after all arch initcalls have
    completed.

    Reported-by: Derek Barbosa <debarbos@redhat.com>
    Closes: https://lore.kernel.org/linux-rt-users/arPmYPbFLf2EldIl@debarbos-thinkpadt14gen5.rmtusma.csb
    Fixes: 76f258bf3f2a ("printk: nbcon: Introduce printer kthreads")
    Signed-off-by: John Ogness <john.ogness@linutronix.de>
    Tested-by: Derek Barbosa <debarbos@redhat.com>
    Link: https://patch.msgid.link/20261016085441.857695-1-john.ogness@linutronix.de
    Signed-off-by: Petr Mladek <pmladek@suse.com>

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6d3d18a50da7..bc3b9f6e404b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3862,7 +3862,7 @@ static int __init printk_set_kthreads_ready(void)

 	return 0;
 }
-early_initcall(printk_set_kthreads_ready);
+subsys_initcall(printk_set_kthreads_ready);
 #endif /* CONFIG_PRINTK */

 static int __read_mostly keep_bootcon;