Re: [PATCH v6 bpf-next 1/3] bpf: enable BPF_PROG_TEST_RUN for raw_tracepoint

On Sep 29, 2020, at 11:24 AM, Alexei Starovoitov [off-list ref] wrote:

On Fri, Sep 25, 2020 at 1:55 PM Song Liu [off-list ref] wrote:

quoted

+
+       if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 ||
+           cpu == smp_processor_id()) {
+               __bpf_prog_test_run_raw_tp(&info);

That's broken:
[   35.874974] BUG: using smp_processor_id() in preemptible [00000000]
code: new_name/87
[   35.893983] caller is bpf_prog_test_run_raw_tp+0xd4/0x1b0
[   35.900124] CPU: 1 PID: 87 Comm: new_name Not tainted 5.9.0-rc6-g615bd02bf #1
[   35.907358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.10.2-1ubuntu1 04/01/2014
[   35.916941] Call Trace:
[   35.919660]  dump_stack+0x77/0x9b
[   35.923273]  check_preemption_disabled+0xb4/0xc0
[   35.928376]  bpf_prog_test_run_raw_tp+0xd4/0x1b0
[   35.933872]  ? selinux_bpf+0xd/0x70
[   35.937532]  __do_sys_bpf+0x6bb/0x21e0
[   35.941570]  ? find_held_lock+0x2d/0x90
[   35.945687]  ? vfs_write+0x150/0x220
[   35.949586]  do_syscall_64+0x2d/0x40
[   35.953443]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Please fix and add debug flags to your .config.

Hmm... I do have most debug flags enabled. But I didn't have CONFIG_PREEMPT. 
I will keep that on..

Thanks,
Song