Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Anssi Hannula <anssi.hannula@bitwise.fi>,
        Michael Kelley <mikelley@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 141/338] hv_balloon: rate-limit "Unhandled message" warning
Date:   Thu, 14 Apr 2022 15:10:44 +0200
Message-Id: <20220414110842.918803617@linuxfoundation.org>
In-Reply-To: <20220414110838.883074566@linuxfoundation.org>
References: <20220414110838.883074566@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Anssi Hannula <anssi.hannula@bitwise.fi>

[ Upstream commit 1d7286729aa616772be334eb908e11f527e1e291 ]

For a couple of times I have encountered a situation where

  hv_balloon: Unhandled message: type: 12447

is being flooded over 1 million times per second with various values,
filling the log and consuming cycles, making debugging difficult.

Add rate limiting to the message.

Most other Hyper-V drivers already have similar rate limiting in their
message callbacks.

The cause of the floods in my case was probably fixed by 96d9d1fa5cd5
("Drivers: hv: balloon: account for vmbus packet header in
max_pkt_size").

Fixes: 9aa8b50b2b3d ("Drivers: hv: Add Hyper-V balloon driver")
Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220222141400.98160-1-anssi.hannula@bitwise.fi
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hv/hv_balloon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index e5fc719a34e7..d442a8d2332e 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -1548,7 +1548,7 @@ static void balloon_onchannelcallback(void *context)
 			break;
 
 		default:
-			pr_warn("Unhandled message: type: %d\n", dm_hdr->type);
+			pr_warn_ratelimited("Unhandled message: type: %d\n", dm_hdr->type);
 
 		}
 	}
-- 
2.34.1