This is a note to let you know that I've just added the patch titled
SUNRPC: avoid soft lockup when transmitting UDP to reachable server.
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sunrpc-avoid-soft-lockup-when-transmitting-udp-to-re.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8a52df8787d24488be89dbaf6fbc5f8975833427
Author: NeilBrown <neilb@xxxxxxx>
Date: Wed Jun 19 11:05:13 2024 +1000
SUNRPC: avoid soft lockup when transmitting UDP to reachable server.
[ Upstream commit 6258cf25d5e3155c3219ab5a79b970eef7996356 ]
Prior to the commit identified below, call_transmit_status() would
handle -EPERM and other errors related to an unreachable server by
falling through to call_status() which added a 3-second delay and
handled the failure as a timeout.
Since that commit, call_transmit_status() falls through to
handle_bind(). For UDP this moves straight on to handle_connect() and
handle_transmit() so we immediately retransmit - and likely get the same
error.
This results in an indefinite loop in __rpc_execute() which triggers a
soft-lockup warning.
For the errors that indicate an unreachable server,
call_transmit_status() should fall back to call_status() as it did
before. This cannot cause the thundering herd that the previous patch
was avoiding, as the call_status() will insert a delay.
Fixes: ed7dc973bd91 ("SUNRPC: Prevent thundering herd when the socket is not connected")
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 2e08876bf8564..f689c7b0c304d 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -2236,12 +2236,13 @@ call_transmit_status(struct rpc_task *task)
task->tk_action = call_transmit;
task->tk_status = 0;
break;
- case -ECONNREFUSED:
case -EHOSTDOWN:
case -ENETDOWN:
case -EHOSTUNREACH:
case -ENETUNREACH:
case -EPERM:
+ break;
+ case -ECONNREFUSED:
if (RPC_IS_SOFTCONN(task)) {
if (!task->tk_msg.rpc_proc->p_proc)
trace_xprt_ping(task->tk_xprt,
