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authorLorenzo Bianconi <lorenzo@kernel.org>2020-07-19 17:52:41 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-07-21 09:15:28 -0700
commitc576b9c77bea9a8ad11ddc277af3edbf15733ddd (patch)
tree9fafd2a3f6f6d21f2afbbd91d9f4b57b06173d39 /kernel/bpf
parent343ead287dde0064c430ee1db477726f52e0269c (diff)
downloadlinux-c576b9c77bea9a8ad11ddc277af3edbf15733ddd.tar.bz2
bpf: cpumap: Fix possible rcpu kthread hung
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> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Jakub Sitnicki <jakub@cloudflare.com> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Link: https://lore.kernel.org/bpf/e54f2aabf959f298939e5507b09c48f8c2e380be.1595170625.git.lorenzo@kernel.org
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/cpumap.c11
1 files 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: