netdev - Re: [PATCH v2 bpf-next] bpf: fix raw

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Message-ID: <CAADnVQ+jaUfJkD0POaRyrmrLueVP9x-rN8bcN5eEz4XPBk96bw@mail.gmail.com>
Date:   Tue, 29 Sep 2020 20:23:58 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Song Liu <songliubraving@...com>
Cc:     Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, Kernel Team <kernel-team@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Subject: Re: [PATCH v2 bpf-next] bpf: fix raw_tp test run in preempt kernel

On Tue, Sep 29, 2020 at 5:20 PM Song Liu <songliubraving@...com> wrote:
>
> In preempt kernel, BPF_PROG_TEST_RUN on raw_tp triggers:
>
> [   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
>
> Fix this by calling migrate_disable() before smp_processor_id().
>
> Fixes: 1b4d60ec162f ("bpf: Enable BPF_PROG_TEST_RUN for raw_tracepoint")
> Reported-by: Alexei Starovoitov <ast@...nel.org>
> Signed-off-by: Song Liu <songliubraving@...com>
>
> ---
> Changes v1 => v2:
> 1. Keep rcu_read_lock/unlock() in original places. (Alexei)
> 2. Use get_cpu() instead of smp_processor_id(). (Alexei)

Applying: bpf: fix raw_tp test run in preempt kernel
Using index info to reconstruct a base tree...
error: patch failed: net/bpf/test_run.c:293
error: net/bpf/test_run.c: patch does not apply
error: Did you hand edit your patch?