In the Linux kernel, the following vulnerability has been resolved: xprtrdma: Decrement...

In the Linux kernel, the following vulnerability has been resolved:

xprtrdma: Decrement re_receiving on the early exit paths

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