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Message-ID: <20130828152745.18a73c4e@gandalf.local.home>
Date: Wed, 28 Aug 2013 15:27:45 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Dave Jones <davej@...hat.com>
Cc: Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
On Wed, 28 Aug 2013 14:29:02 -0400
> > >
> > > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> > > index 80c36bc..05167bb 100644
> > > --- a/kernel/trace/trace_event_perf.c
> > > +++ b/kernel/trace/trace_event_perf.c
> > > @@ -306,6 +306,7 @@ static int perf_ftrace_function_unregister(struct perf_event *event)
> > > {
> > > struct ftrace_ops *ops = &event->ftrace_ops;
> > > int ret = unregister_ftrace_function(ops);
> > > + WARN_ON(ret);
> > > ftrace_free_filter(ops);
> > > return ret;
> > > }
> >
> > I hit the WARN in the subject, and then this new one immediately afterwards.
Grumble. Then what I thought it might be, it isn't.
>
> actually looking closer..
>
> [ 6619.050768] WARNING: CPU: 1 PID: 16351 at kernel/trace/ftrace.c:1640 __ftrace_hash_rec_update.part.37+0x20a/0x240()
> [ 6619.053767] Modules linked in: lec snd_seq_dummy bridge stp fuse tun bnep hidp rfcomm nfnetlink ipt_ULOG scsi_transport_iscsi can_bcm can_raw nfc caif_socket caif af_802154 phonet af_rxrpc bluetooth rfkill can llc2 pppoe pppox ppp_generic slhc irda crc_ccitt rds af_key rose x25 atm netrom appletalk ipx p8023 psnap p8022 llc ax25 xfs libcrc32c snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device snd_pcm snd_page_alloc e1000e ptp snd_timer pcspkr pps_core snd soundcore usb_debug
> [ 6619.060523] CPU: 1 PID: 16351 Comm: trinity-child2 Not tainted 3.11.0-rc7+ #31
> [ 6619.062161] ffffffff81a21901 ffff8802267b9ce0 ffffffff816f9e4f 0000000000000000
> [ 6619.063733] ffff8802267b9d18 ffffffff81052dcd 0000000000000000 0000000000000001
> [ 6619.065309] ffff8802203a3000 0000000000000000 ffff880225e962d0 ffff8802267b9d28
> [ 6619.066895] Call Trace:
> [ 6619.068437] [<ffffffff816f9e4f>] dump_stack+0x54/0x74
> [ 6619.070046] [<ffffffff81052dcd>] warn_slowpath_common+0x7d/0xa0
> [ 6619.071642] [<ffffffff81052eaa>] warn_slowpath_null+0x1a/0x20
> [ 6619.073224] [<ffffffff81115d1a>] __ftrace_hash_rec_update.part.37+0x20a/0x240
> [ 6619.074817] [<ffffffff81117e18>] ftrace_shutdown+0xb8/0x160
> [ 6619.076399] [<ffffffff811182a0>] unregister_ftrace_function+0x30/0x50
> [ 6619.077983] [<ffffffff81135e57>] perf_ftrace_event_register+0x87/0x150
> [ 6619.079565] [<ffffffff81135cdc>] perf_trace_destroy+0x2c/0x50
> [ 6619.081180] [<ffffffff8113df49>] tp_perf_event_destroy+0x9/0x10
> [ 6619.082742] [<ffffffff81140527>] free_event+0xa7/0x300
> [ 6619.084264] [<ffffffff81141620>] __perf_event_exit_task+0xe0/0x130
> [ 6619.085792] [<ffffffff8114a491>] perf_event_exit_task+0x1f1/0x230
> [ 6619.087329] [<ffffffff810546dd>] do_exit+0x30d/0xcd0
> [ 6619.088860] [<ffffffff8170cfc0>] ? ftrace_call+0x5/0x2f
> [ 6619.090460] [<ffffffff8105643c>] do_group_exit+0x4c/0xc0
> [ 6619.092036] [<ffffffff810564c4>] SyS_exit_group+0x14/0x20
> [ 6619.093614] [<ffffffff8170d594>] tracesys+0xdd/0xe2
>
> [ 6620.015243] ------------[ cut here ]------------
> [ 6620.018093] WARNING: CPU: 3 PID: 17998 at kernel/trace/trace_event_perf.c:309 perf_ftrace_event_register+0x13f/0x150()
> [ 6620.022809] Modules linked in: lec snd_seq_dummy bridge stp fuse tun bnep hidp rfcomm nfnetlink ipt_ULOG scsi_transport_iscsi can_bcm can_raw nfc caif_socket caif af_802154 phonet af_rxrpc bluetooth rfkill can llc2 pppoe pppox ppp_generic slhc irda crc_ccitt rds af_key rose x25 atm netrom appletalk ipx p8023 psnap p8022 llc ax25 xfs libcrc32c snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device snd_pcm snd_page_alloc e1000e ptp snd_timer pcspkr pps_core snd soundcore usb_debug
> [ 6620.029752] CPU: 3 PID: 17998 Comm: trinity-child3 Tainted: G W 3.11.0-rc7+ #31
> [ 6620.033043] ffffffff81a185c0 ffff8801e80b1d78 ffffffff816f9e4f 0000000000000000
> [ 6620.034676] ffff8801e80b1db0 ffffffff81052dcd ffff8801f308f3b8 00000000ffffffed
> [ 6620.036314] ffff8801f308f1e0 ffff8802266d01d8 0000000000000001 ffff8801e80b1dc0
> [ 6620.038041] Call Trace:
> [ 6620.039743] [<ffffffff816f9e4f>] dump_stack+0x54/0x74
> [ 6620.041430] [<ffffffff81052dcd>] warn_slowpath_common+0x7d/0xa0
> [ 6620.043131] [<ffffffff81052eaa>] warn_slowpath_null+0x1a/0x20
> [ 6620.044810] [<ffffffff81135f0f>] perf_ftrace_event_register+0x13f/0x150
> [ 6620.046492] [<ffffffff81135cdc>] perf_trace_destroy+0x2c/0x50
> [ 6620.048168] [<ffffffff8113df49>] tp_perf_event_destroy+0x9/0x10
> [ 6620.049876] [<ffffffff81140527>] free_event+0xa7/0x300
> [ 6620.051545] [<ffffffff81141620>] __perf_event_exit_task+0xe0/0x130
> [ 6620.053204] [<ffffffff8114a491>] perf_event_exit_task+0x1f1/0x230
> [ 6620.054852] [<ffffffff810546dd>] do_exit+0x30d/0xcd0
> [ 6620.056482] [<ffffffff8170cfc0>] ? ftrace_call+0x5/0x2f
> [ 6620.058098] [<ffffffff8105643c>] do_group_exit+0x4c/0xc0
> [ 6620.059739] [<ffffffff810564c4>] SyS_exit_group+0x14/0x20
> [ 6620.061348] [<ffffffff8170d594>] tracesys+0xdd/0xe2
> [ 6620.062955] ---[ end trace c7d2bbab21000c60 ]---
>
> note how they're different CPUs & pids. Relevant ?
Unfortunately no.
The first failure disables function tracing completely, which is one of
the causes to return an error, which triggered the warning I added.
I was hoping that it failed for another reason and then that would
cause things to break. But you said the hash corruption happened first
(the original bug), so that's not the case.
Back to staring at code.
Thanks,
-- Steve
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