On Mon, Oct 09, 2017 at 04:07:18AM +0000, Eric Dumazet wrote:
> From: Eric Dumazet <eduma...@google.com>
>
> Ido reported following splat and provided a patch.
>
> [ 122.221814] BUG: using smp_processor_id() in preemptible [00000000] code:
> sshd/2672
> [ 122.221845] caller is debug_smp_processor_id+0x17/0x20
> [ 122.221866] CPU: 0 PID: 2672 Comm: sshd Not tainted
> 4.14.0-rc3-idosch-next-custom #639
> [ 122.221880] Hardware name: Mellanox Technologies Ltd.
> MSN2100-CB2FO/SA001017, BIOS 5.6.5 06/07/2016
> [ 122.221893] Call Trace:
> [ 122.221919] dump_stack+0xb1/0x10c
> [ 122.221946] ? _atomic_dec_and_lock+0x124/0x124
> [ 122.221974] ? ___ratelimit+0xfe/0x240
> [ 122.222020] check_preemption_disabled+0x173/0x1b0
> [ 122.222060] debug_smp_processor_id+0x17/0x20
> [ 122.222083] ip6_pol_route+0x1482/0x24a0
> ...
>
> I believe we can simplify this code path a bit, since we no longer
> hold a read_lock and need to release it to avoid a dead lock.
>
> By disabling BH, we make sure we'll prevent code re-entry and
> rt6_get_pcpu_route()/rt6_make_pcpu_route() run on the same cpu.
Thanks for fixing it!
