* [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung
@ 2020-07-19 15:52 Lorenzo Bianconi
2020-07-20 9:14 ` Jakub Sitnicki
2020-07-21 10:26 ` Jakub Sitnicki
0 siblings, 2 replies; 6+ messages in thread
From: Lorenzo Bianconi @ 2020-07-19 15:52 UTC (permalink / raw)
To: netdev, bpf; +Cc: davem, ast, brouer, daniel, lorenzo.bianconi, jakub, kuba
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@cloudflare.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
kernel/bpf/cpumap.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 4c95d0615ca2..f1c46529929b 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -453,24 +453,27 @@ __cpu_map_entry_alloc(struct bpf_cpumap_val *value, u32 cpu, int map_id)
rcpu->map_id = map_id;
rcpu->value.qsize = value->qsize;
+ if (fd > 0 && __cpu_map_load_bpf_program(rcpu, fd))
+ goto free_ptr_ring;
+
/* Setup kthread */
rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa,
"cpumap/%d/map:%d", cpu, map_id);
if (IS_ERR(rcpu->kthread))
- goto free_ptr_ring;
+ goto free_prog;
get_cpu_map_entry(rcpu); /* 1-refcnt for being in cmap->cpu_map[] */
get_cpu_map_entry(rcpu); /* 1-refcnt for kthread */
- if (fd > 0 && __cpu_map_load_bpf_program(rcpu, fd))
- goto free_ptr_ring;
-
/* Make sure kthread runs on a single CPU */
kthread_bind(rcpu->kthread, cpu);
wake_up_process(rcpu->kthread);
return rcpu;
+free_prog:
+ if (rcpu->prog)
+ bpf_prog_put(rcpu->prog);
free_ptr_ring:
ptr_ring_cleanup(rcpu->queue, NULL);
free_queue:
--
2.26.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung
2020-07-19 15:52 [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung Lorenzo Bianconi
@ 2020-07-20 9:14 ` Jakub Sitnicki
2020-07-20 15:45 ` David Ahern
2020-07-21 10:26 ` Jakub Sitnicki
1 sibling, 1 reply; 6+ messages in thread
From: Jakub Sitnicki @ 2020-07-20 9:14 UTC (permalink / raw)
To: Lorenzo Bianconi
Cc: netdev, bpf, davem, ast, brouer, daniel, lorenzo.bianconi, kuba
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@cloudflare.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
> kernel/bpf/cpumap.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
> index 4c95d0615ca2..f1c46529929b 100644
> --- a/kernel/bpf/cpumap.c
> +++ b/kernel/bpf/cpumap.c
> @@ -453,24 +453,27 @@ __cpu_map_entry_alloc(struct bpf_cpumap_val *value, u32 cpu, int map_id)
> rcpu->map_id = map_id;
> rcpu->value.qsize = value->qsize;
>
> + if (fd > 0 && __cpu_map_load_bpf_program(rcpu, fd))
> + goto free_ptr_ring;
> +
I realize it's a code move, but fd == 0 is a valid descriptor number.
The check is too strict, IMHO.
> /* Setup kthread */
> rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa,
> "cpumap/%d/map:%d", cpu, map_id);
> if (IS_ERR(rcpu->kthread))
> - goto free_ptr_ring;
> + goto free_prog;
>
> get_cpu_map_entry(rcpu); /* 1-refcnt for being in cmap->cpu_map[] */
> get_cpu_map_entry(rcpu); /* 1-refcnt for kthread */
>
> - if (fd > 0 && __cpu_map_load_bpf_program(rcpu, fd))
> - goto free_ptr_ring;
> -
> /* Make sure kthread runs on a single CPU */
> kthread_bind(rcpu->kthread, cpu);
> wake_up_process(rcpu->kthread);
>
> return rcpu;
>
> +free_prog:
> + if (rcpu->prog)
> + bpf_prog_put(rcpu->prog);
> free_ptr_ring:
> ptr_ring_cleanup(rcpu->queue, NULL);
> free_queue:
Hung task splat is gone:
Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung
2020-07-20 9:14 ` Jakub Sitnicki
@ 2020-07-20 15:45 ` David Ahern
2020-07-21 10:21 ` Jakub Sitnicki
0 siblings, 1 reply; 6+ messages in thread
From: David Ahern @ 2020-07-20 15:45 UTC (permalink / raw)
To: Jakub Sitnicki, Lorenzo Bianconi
Cc: netdev, bpf, davem, ast, brouer, daniel, lorenzo.bianconi, kuba
On 7/20/20 3:14 AM, Jakub Sitnicki wrote:
> I realize it's a code move, but fd == 0 is a valid descriptor number.
this follows the decision made for devmap entries in that fd == 0 is NOT
a valid program fd.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung
2020-07-20 15:45 ` David Ahern
@ 2020-07-21 10:21 ` Jakub Sitnicki
0 siblings, 0 replies; 6+ messages in thread
From: Jakub Sitnicki @ 2020-07-21 10:21 UTC (permalink / raw)
To: David Ahern
Cc: Lorenzo Bianconi, netdev, bpf, davem, ast, brouer, daniel,
lorenzo.bianconi, kuba
On Mon, Jul 20, 2020 at 05:45 PM CEST, David Ahern wrote:
> On 7/20/20 3:14 AM, Jakub Sitnicki wrote:
>> I realize it's a code move, but fd == 0 is a valid descriptor number.
>
> this follows the decision made for devmap entries in that fd == 0 is NOT
> a valid program fd.
Surprising. Thanks for clarifying.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung
2020-07-19 15:52 [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung Lorenzo Bianconi
2020-07-20 9:14 ` Jakub Sitnicki
@ 2020-07-21 10:26 ` Jakub Sitnicki
2020-07-21 16:20 ` Alexei Starovoitov
1 sibling, 1 reply; 6+ messages in thread
From: Jakub Sitnicki @ 2020-07-21 10:26 UTC (permalink / raw)
To: Lorenzo Bianconi
Cc: netdev, bpf, davem, ast, brouer, daniel, lorenzo.bianconi, kuba
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@cloudflare.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung
2020-07-21 10:26 ` Jakub Sitnicki
@ 2020-07-21 16:20 ` Alexei Starovoitov
0 siblings, 0 replies; 6+ messages in thread
From: Alexei Starovoitov @ 2020-07-21 16:20 UTC (permalink / raw)
To: Jakub Sitnicki
Cc: Lorenzo Bianconi, Network Development, bpf, David S. Miller,
Alexei Starovoitov, Jesper Dangaard Brouer, Daniel Borkmann,
lorenzo.bianconi, Jakub Kicinski
On Tue, Jul 21, 2020 at 3:26 AM Jakub Sitnicki <jakub@cloudflare.com> wrote:
>
> 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@cloudflare.com>
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > ---
>
> Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Applied. Thanks
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-07-21 16:20 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-19 15:52 [PATCH bpf-next] bpf: cpumap: fix possible rcpu kthread hung Lorenzo Bianconi
2020-07-20 9:14 ` Jakub Sitnicki
2020-07-20 15:45 ` David Ahern
2020-07-21 10:21 ` Jakub Sitnicki
2020-07-21 10:26 ` Jakub Sitnicki
2020-07-21 16:20 ` Alexei Starovoitov
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