[PATCH 5.16 0566/1017] hv_balloon: rate-limit "Unhandled message" warning

Greg Kroah-Hartman
2022-04-05T09:51:47Z

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 f2d05bff4245..439f99b8b5de 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -1563,7 +1563,7 @@ 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