On Sun, Jul 19, 2020 at 05:52 PM CEST, Lorenzo Bianconi wrote:
> Fix the following cpumap kthread hung. The issue is currently occurring
> when __cpu_map_load_bpf_program fails (e.g if the bpf prog has not
> BPF_XDP_CPUMAP as expected_attach_type)
>
> $./test_progs -n 101
> 101/1 cpumap_with_progs:OK
> 101 xdp_cpumap_attach:OK
> Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED
> [ 369.996478] INFO: task cpumap/0/map:7:205 blocked for more than 122 seconds.
> [ 369.998463] Not tainted 5.8.0-rc4-01472-ge57892f50a07 #212
> [ 370.000102] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 370.001918] cpumap/0/map:7 D 0 205 2 0x00004000
> [ 370.003228] Call Trace:
> [ 370.003930] __schedule+0x5c7/0xf50
> [ 370.004901] ? io_schedule_timeout+0xb0/0xb0
> [ 370.005934] ? static_obj+0x31/0x80
> [ 370.006788] ? mark_held_locks+0x24/0x90
> [ 370.007752] ? cpu_map_bpf_prog_run_xdp+0x6c0/0x6c0
> [ 370.008930] schedule+0x6f/0x160
> [ 370.009728] schedule_preempt_disabled+0x14/0x20
> [ 370.010829] kthread+0x17b/0x240
> [ 370.011433] ? kthread_create_worker_on_cpu+0xd0/0xd0
> [ 370.011944] ret_from_fork+0x1f/0x30
> [ 370.012348]
> Showing all locks held in the system:
> [ 370.013025] 1 lock held by khungtaskd/33:
> [ 370.013432] #0: ffffffff82b24720 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x28/0x1c3
>
> [ 370.014461] =============================================
>
> Fixes: 9216477449f3 ("bpf: cpumap: Add the possibility to attach an eBPF program to cpumap")
> Reported-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> ---
Tested-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Reviewed-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
