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

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Message-ID: <8EFE87FC-84D2-4B63-B057-804A6F9F1F63@fb.com>
Date:   Wed, 30 Sep 2020 15:48:13 +0000
From:   Song Liu <songliubraving@...com>
To:     Alexei Starovoitov <ast@...com>
CC:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        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 Sep 30, 2020, at 8:35 AM, Alexei Starovoitov <ast@...com> wrote:
> 
> On 9/29/20 11:45 PM, Song Liu wrote:
>>> On Sep 29, 2020, at 8:23 PM, Alexei Starovoitov <alexei.starovoitov@...il.com> wrote:
>>> 
>>> 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?
>> This is so weird. I cannot apply it myself. :(
>> [localhost] g co -b bpf-next-temp
>> Switched to a new branch 'bpf-next-temp'
>> [localhost] g format-patch -b HEAD~1 --subject-prefix "PATCH v3 bpf-next"
>> 0001-bpf-fix-raw_tp-test-run-in-preempt-kernel.patch
> 
> could you try without -b ?

Yes! -b is the problem here. 

I think the right way to format-patch is to use --ignore-space-at-eol 
instead of -b. 

Thanks,
Song