[PATCH 6.18 028/333] xprtrdma: Decrement re_receiving on the early exit paths

Greg Kroah-Hartman
2026-03-17T17:06:05Z

From: Eric Badger <ebadger@purestorage.com>

[ Upstream commit 7b6275c80a0c81c5f8943272292dfe67730ce849 ]

In the event that rpcrdma_post_recvs() fails to create a work request
(due to memory allocation failure, say) or otherwise exits early, we
should decrement ep->re_receiving before returning. Otherwise we will
hang in rpcrdma_xprt_drain() as re_receiving will never reach zero and
the completion will never be triggered.

On a system with high memory pressure, this can appear as the following
hung task:

INFO: task kworker/u385:17:8393 blocked for more than 122 seconds.
Tainted: G S E 6.19.0 #3
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u385:17 state:D stack:0 pid:8393 tgid:8393 ppid:2 task_flags:0x4248060 flags:0x00080000
Workqueue: xprtiod xprt_autoclose [sunrpc]
Call Trace:
<TASK>
__schedule+0x48b/0x18b0
? ib_post_send_mad+0x247/0xae0 [ib_core]
schedule+0x27/0xf0
schedule_timeout+0x104/0x110
__wait_for_common+0x98/0x180
? __pfx_schedule_timeout+0x10/0x10
wait_for_completion+0x24/0x40
rpcrdma_xprt_disconnect+0x444/0x460 [rpcrdma]
xprt_rdma_close+0x12/0x40 [rpcrdma]
xprt_autoclose+0x5f/0x120 [sunrpc]
process_one_work+0x191/0x3e0
worker_thread+0x2e3/0x420
? __pfx_worker_thread+0x10/0x10
kthread+0x10d/0x230
? __pfx_kthread+0x10/0x10
ret_from_fork+0x273/0x2b0
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30

Fixes: 15788d1d1077 ("xprtrdma: Do not refresh Receive Queue while it is draining")
Signed-off-by: Eric Badger <ebadger@purestorage.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sunrpc/xprtrdma/verbs.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 63262ef0c2e3a..8abbd9c4045a4 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1362,7 +1362,7 @@ void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed)
needed += RPCRDMA_MAX_RECV_BATCH;

if (atomic_inc_return(&ep->re_receiving) > 1)
- goto out;
+ goto out_dec;

/* fast path: all needed reps can be found on the free list */
wr = NULL;
@@ -1385,7 +1385,7 @@ void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed)
++count;
}
if (!wr)
- goto out;
+ goto out_dec;

rc = ib_post_recv(ep->re_id->qp, wr,
(const struct ib_recv_wr **)&bad_wr);
@@ -1400,9 +1400,10 @@ void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed)
--count;
}
}
+
+out_dec:
if (atomic_dec_return(&ep->re_receiving) > 0)
complete(&ep->re_done);
-
out:
trace_xprtrdma_post_recvs(r_xprt, count);
ep->re_receive_count += count;
--
2.51.0