[PATCH] x86/nmi: ratelimit unknown nmi logs

From: Olof Johansson <olof@lixom.net>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Olof Johansson <olof@lixom.net>
Subject: [PATCH] x86/nmi: ratelimit unknown nmi logs
Date: Tue, 19 Feb 2019 17:48:36 -0800	[thread overview]
Message-ID: <20190220014836.20510-1-olof@lixom.net> (raw)

Getting notified of unknown NMIs is obviously important, but getting
notified on every single one, especially on larger systems with slow
(serial) console causes more harm than good when it's a known noisy
non-relevant event.

So, let's ratelimit to avoid locking up the system.

Signed-off-by: Olof Johansson <olof@lixom.net>
---
 arch/x86/kernel/nmi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 18bc9b51ac9b9..44050cbfee136 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -292,14 +292,14 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 
 	__this_cpu_add(nmi_stats.unknown, 1);
 
-	pr_emerg("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
+	pr_emerg_ratelimited("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
 		 reason, smp_processor_id());
 
-	pr_emerg("Do you have a strange power saving mode enabled?\n");
+	pr_emerg_ratelimited("Do you have a strange power saving mode enabled?\n");
 	if (unknown_nmi_panic || panic_on_unrecovered_nmi)
 		nmi_panic(regs, "NMI: Not continuing");
 
-	pr_emerg("Dazed and confused, but trying to continue\n");
+	pr_emerg_ratelimited("Dazed and confused, but trying to continue\n");
 }
 NOKPROBE_SYMBOL(unknown_nmi_error);
 
-- 
2.11.0

