5.4-stable review patch. If anyone has any objections, please let me know.
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From: John Ogness john.ogness@linutronix.de
[ Upstream commit d988d9a9b9d180bfd5c1d353b3b176cb90d6861b ]
If the kernel crashes in a context where printk() calls always defer printing (such as in NMI or inside a printk_safe section) then the final panic messages will be deferred to irq_work. But if irq_work is not available, the messages will not get printed unless explicitly flushed. The result is that the final "end Kernel panic" banner does not get printed.
Add one final flush after the last printk() call to make sure the final panic messages make it out as well.
Signed-off-by: John Ogness john.ogness@linutronix.de Reviewed-by: Petr Mladek pmladek@suse.com Link: https://lore.kernel.org/r/20240207134103.1357162-14-john.ogness@linutronix.d... Signed-off-by: Petr Mladek pmladek@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/panic.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/kernel/panic.c b/kernel/panic.c index cef79466f9417..5559a6e4c4579 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -404,6 +404,14 @@ void panic(const char *fmt, ...)
/* Do not scroll important messages printed above */ suppress_printk = 1; + + /* + * The final messages may not have been printed if in a context that + * defers printing (such as NMI) and irq_work is not available. + * Explicitly flush the kernel log buffer one last time. + */ + console_flush_on_panic(CONSOLE_FLUSH_PENDING); + local_irq_enable(); for (i = 0; ; i += PANIC_TIMER_STEP) { touch_softlockup_watchdog();