linux-kernel - Re: [PATCH 0/6] ftrace: port to the new ring

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Date:	Tue, 30 Sep 2008 10:23:02 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mathieu Desnoyers <compudj@...stal.dyndns.org>
Subject: Re: [PATCH 0/6] ftrace: port to the new ring_buffer


* Ingo Molnar <mingo@...e.hu> wrote:

> very nice! I'd expect breakages and complications too so i 
> restructured tip/tracing/* a bit: firstly i created a tip/tracing/core 
> append-only merge branch which collects all the known-robust bits. 
> Then i created a new branch for your new generic ring-buffer feature: 
> tip/tracing/ring-buffer, and applied your patches. I've started 
> testing it.

-tip testing found that tip/tracing/ring-buffer causes a new lockdep 
splat:

[    0.000000] Linux version 2.6.27-rc8-tip-00915-g8cb18a9-dirty (mingo@...ne)
               (gcc version 4.2.3) #37501 SMP Tue Sep 30 10:10:10 CEST 2008
[...]
[    0.268001] calling  tracer_alloc_buffers+0x0/0x1e5 @ 1
[    0.270983] ------------[ cut here ]------------
[    0.271100] WARNING: at kernel/lockdep.c:2880 check_flags+0x63/0x179()
[    0.271219] Modules linked in:
[    0.271356] Pid: 1, comm: swapper Not tainted 2.6.27-rc8-tip-00915-g8cb18a9-dirty #37501
[    0.271563] Call Trace:
[    0.271678]  [<ffffffff80271d2b>] warn_on_slowpath+0x5d/0x84
[    0.271797]  [<ffffffff80295973>] ? __lock_acquire+0xba4/0xbc5
[    0.271916]  [<ffffffff8029266d>] ? __raw_spin_is_locked+0x17/0x1a
[    0.272001]  [<ffffffff802929cc>] ? graph_unlock+0x79/0x7e
[    0.272001]  [<ffffffff8029449f>] ? mark_lock+0x1c/0x361
[    0.272001]  [<ffffffff8029483a>] ? mark_held_locks+0x56/0x71
[    0.272001]  [<ffffffff802cbb77>] ? time_hardirqs_off+0x12/0x26
[    0.272001]  [<ffffffff802934f1>] ? trace_hardirqs_off_caller+0x21/0xc2
[    0.272001]  [<ffffffff802927c3>] check_flags+0x63/0x179
[    0.272001]  [<ffffffff802966a1>] lock_acquire+0x51/0xc2
[    0.272001]  [<ffffffff816fcead>] _spin_lock+0x36/0x65
[    0.272001]  [<ffffffff802c7511>] ? ring_buffer_reset_cpu+0x47/0x6b
[    0.272001]  [<ffffffff802c7511>] ring_buffer_reset_cpu+0x47/0x6b
[    0.272001]  [<ffffffff802ca33f>] tracing_reset+0xc/0xe
[    0.272001]  [<ffffffff802cd0b4>] boot_trace_init+0x2a/0x46
[    0.272001]  [<ffffffff826817c3>] tracer_alloc_buffers+0x1a7/0x1e5
[    0.272001]  [<ffffffff8268161c>] ? tracer_alloc_buffers+0x0/0x1e5
[    0.272001]  [<ffffffff8020a062>] do_one_initcall+0x62/0x165
[    0.272001]  [<ffffffff816f3291>] ? print_cpu_info+0xab/0x135
[    0.272001]  [<ffffffff8024d8aa>] ? get_apic_id+0x0/0x13
[    0.272001]  [<ffffffff8268161c>] ? tracer_alloc_buffers+0x0/0x1e5
[    0.272001]  [<ffffffff8266190c>] kernel_init+0x60/0x21a
[    0.272001]  [<ffffffff8022daf9>] child_rip+0xa/0x11
[    0.272001]  [<ffffffff8022cc83>] ? restore_args+0x0/0x30
[    0.272001]  [<ffffffff802c5d03>] ? ftrace_convert_nops+0x25/0xb0
[    0.272001]  [<ffffffff8023362a>] ? sched_clock+0x17/0x1a
[    0.272001]  [<ffffffff826618ac>] ? kernel_init+0x0/0x21a
[    0.272001]  [<ffffffff8022daef>] ? child_rip+0x0/0x11
[    0.272001] ---[ end trace a7919e7f17c0a725 ]---
[    0.272001] possible reason: unannotated irqs-off.
[    0.272001] irq event stamp: 9069
[    0.272001] hardirqs last  enabled at (9069): [<ffffffff802949bf>] trace_hardirqs_on+0xd/0xf
[    0.272001] hardirqs last disabled at (9068): [<ffffffff8029359f>] trace_hardirqs_off+0xd/0xf
[    0.272001] softirqs last  enabled at (4082): [<ffffffff802773c3>] __do_softirq+0xe0/0xed
[    0.272001] softirqs last disabled at (4075): [<ffffffff8022dfec>] call_softirq+0x1c/0x28
[    0.272010] initcall tracer_alloc_buffers+0x0/0x1e5 returned 0 after 7 msecs
[    0.272409] lockdep: fixing up alternatives.
[    0.272604] Booting processor 1 APIC 0x1 ip 0x6000
[    0.004000] Initializing CPU#1

on a 64-bit allyesconfig bootup. Config attached.

The box booted up fine otherwise, so i'll continue testing the new code, 
to find other problems (if any).

	Ingo

View attachment "config" of type "text/plain" (88380 bytes)