netdev - Re: [PATCH bpf v2] cpumap: Avoid warning when CONFIG_DEBUG_PER_CPU

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Date:   Mon, 20 Apr 2020 18:40:47 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Toke Høiland-Jørgensen <toke@...hat.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...com>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Xiumei Mu <xmu@...hat.com>
Subject: Re: [PATCH bpf v2] cpumap: Avoid warning when CONFIG_DEBUG_PER_CPU_MAPS
 is enabled

On Thu, Apr 16, 2020 at 1:33 AM Toke Høiland-Jørgensen <toke@...hat.com> wrote:
>
> When the kernel is built with CONFIG_DEBUG_PER_CPU_MAPS, the cpumap code
> can trigger a spurious warning if CONFIG_CPUMASK_OFFSTACK is also set. This
> happens because in this configuration, NR_CPUS can be larger than
> nr_cpumask_bits, so the initial check in cpu_map_alloc() is not sufficient
> to guard against hitting the warning in cpumask_check().
>
> Fix this by explicitly checking the supplied key against the
> nr_cpumask_bits variable before calling cpu_possible().
>
> Fixes: 6710e1126934 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP")
> Cc: Jesper Dangaard Brouer <brouer@...hat.com>
> Reported-by: Xiumei Mu <xmu@...hat.com>
> Tested-by: Xiumei Mu <xmu@...hat.com>
> Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>

Applied. Thanks