Re: [flow_cache_new_hashrnd] WARNING: at kernel/smp.c:328 smp_call_function_single()

Ingo Molnar
2013-02-11T09:03:16Z

* Fengguang Wu <fengguang.wu@intel.com> wrote:

> Greetings,
>
> I got the below oops and the first bad commit is

It's a one-time warning, not an actual crash, right?

> commit b29f39c7c3e75a741a7da88244ec707f293ec04c
> Author: Chuansheng Liu <chuansheng.liu@intel.com>
> Date: Wed Feb 6 23:18:21 2013 +0800
>
> smp: Give WARN()ing if in_interrupt() when calling smp_call_function_many()/single()

So this commit was supposed to warn about instances where an IPI
is generated from hardirq context in essence.

But this:

> [ 229.341176] [<ffffffff810353b4>] warn_slowpath_common+0x83/0x9c
> [ 229.343091] [<ffffffff817089d6>] ? flow_cache_new_hashrnd+0x98/0x98
> [ 229.345105] [<ffffffff810353e7>] warn_slowpath_null+0x1a/0x1c
> [ 229.346978] [<ffffffff81090793>] smp_call_function_single+0xbd/0x1c7
> [ 229.349017] [<ffffffff81090afe>] smp_call_function_many+0x121/0x23e
> [ 229.350996] [<ffffffff817089d6>] ? flow_cache_new_hashrnd+0x98/0x98
> [ 229.353005] [<ffffffff81090e09>] smp_call_function+0x37/0x40
> [ 229.354860] [<ffffffff8170907e>] flow_cache_flush+0x72/0xa0
> [ 229.356735] [<ffffffff81759e33>] xfrm_dev_event+0x14/0x20
> [ 229.358545] [<ffffffff817ff8b0>] notifier_call_chain+0x65/0x95
> [ 229.360469] [<ffffffff8105ce16>] __raw_notifier_call_chain+0xe/0x10
> [ 229.362453] [<ffffffff8105ce2c>] raw_notifier_call_chain+0x14/0x16
> [ 229.364453] [<ffffffff816f63d6>] call_netdevice_notifiers+0x4a/0x4f
> [ 229.366434] [<ffffffff816fa2ab>] __dev_notify_flags+0x37/0x5b
> [ 229.368342] [<ffffffff816fa318>] dev_change_flags+0x49/0x54
> [ 229.370184] [<ffffffff8174574a>] devinet_ioctl+0x24f/0x542
> [ 229.372036] [<ffffffff81746975>] inet_ioctl+0x97/0xb1
> [ 229.373774] [<ffffffff816e5042>] sock_do_ioctl.constprop.42+0x18/0x37
> [ 229.375791] [<ffffffff816e5480>] sock_ioctl+0x1fd/0x20a
> [ 229.377648] [<ffffffff810bb9cd>] ? trace_buffer_lock_reserve+0x41/0x56
> [ 229.379701] [<ffffffff8112b7c6>] vfs_ioctl+0x26/0x39
> [ 229.381459] [<ffffffff8112c0d2>] do_vfs_ioctl+0x41b/0x45e
> [ 229.383269] [<ffffffff8100bc3a>] ? ftrace_raw_event_sys_enter+0x10b/0x11a
> [ 229.385404] [<ffffffff817fc118>] ? retint_swapgs+0x13/0x1b
> [ 229.387227] [<ffffffff8112c15a>] sys_ioctl+0x45/0x73
> [ 229.388975] [<ffffffff818034be>] tracesys+0xd0/0xd5
> [ 229.390665] ---[ end trace c47a5dd12e99cb04 ]---

... is syscall/ioctl context, so the warning is bogus - possibly
the notifier there runs with bhs disabled and thus
in_interrupt() triggers?

It should probably use in_irq() - while double checking whether
that works on non-genirq platforms.

Anyway, the commit needs more work so I've zapped the commit for
now.

Thanks,

Ingo