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From:   Y Song <ys114321@gmail.com>
Date:   Fri, 16 Nov 2018 23:30:59 +0000
Message-ID: <CAH3MdRUxuoe98m-ui9JQOhUT+xZxW-yVM1Wkpa4fkxvkMgt_BA@mail.gmail.com>
Subject: Re: [PATCH bpf] bpf: allocate local storage buffers using GFP_ATOMIC
To:     guroan@gmail.com
Cc:     netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, kernel-team@fb.com,
        guro@fb.com, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>
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On Wed, Nov 14, 2018 at 6:01 PM Roman Gushchin <guroan@gmail.com> wrote:
>
> Naresh reported an issue with the non-atomic memory allocation of
> cgroup local storage buffers:
>
> [   73.047526] BUG: sleeping function called from invalid context at
> /srv/oe/build/tmp-rpb-glibc/work-shared/intel-corei7-64/kernel-source/mm/slab.h:421
> [   73.060915] in_atomic(): 1, irqs_disabled(): 0, pid: 3157, name: test_cgroup_sto
> [   73.068342] INFO: lockdep is turned off.
> [   73.072293] CPU: 2 PID: 3157 Comm: test_cgroup_sto Not tainted
> 4.20.0-rc2-next-20181113 #1
> [   73.080548] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS
> 2.0b 07/27/2017
> [   73.088018] Call Trace:
> [   73.090463]  dump_stack+0x70/0xa5
> [   73.093783]  ___might_sleep+0x152/0x240
> [   73.097619]  __might_sleep+0x4a/0x80
> [   73.101191]  __kmalloc_node+0x1cf/0x2f0
> [   73.105031]  ? cgroup_storage_update_elem+0x46/0x90
> [   73.109909]  cgroup_storage_update_elem+0x46/0x90
>
> cgroup_storage_update_elem() (as well as other update map update
> callbacks) is called with disabled preemption, so GFP_ATOMIC
> allocation should be used: e.g. alloc_htab_elem() in hashtab.c.
>
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>

Acked-by: Yonghong Song <yhs@fb.com>

> ---
>  kernel/bpf/local_storage.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)