Messages in this thread | | | Date | Thu, 16 Apr 2009 23:03:28 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: [PATCH 2/2] tracing/events/lockdep: move tracepoints within recursive protection |
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On Thu, 16 Apr 2009, Peter Zijlstra wrote:
> On Thu, 2009-04-16 at 13:45 -0400, Steven Rostedt wrote: > > On Thu, 16 Apr 2009, Peter Zijlstra wrote: > > > > > On Thu, 2009-04-16 at 12:15 -0400, Steven Rostedt wrote: > > > > plain text document attachment > > > > (0002-tracing-events-lockdep-move-tracepoints-within-recu.patch) > > > > From: Steven Rostedt <srostedt@redhat.com> > > > > > > > > With the current location of the tracepoints in lockdep, the system > > > > can hard lockup in minutes when the tracepoints are enabled. > > > > > > > > Moving the tracepoints outside inside the lockdep protection solves > > > > the issue. > > > > > > NAK > > > > Can we at least add this as a workaround. Basically, the lockdep > > tracepoints are broken as is. I do not plan on changing the logic of the > > events to prevent nesting. That's a feature I use. If we don't allow > > nesting, we must drop events, which is bad. > > No, I would say any nesting is a bug, and should stop tracing and print > a splat. No need to drop events. > > > The other answer is simply to remove the trace points in lockdep, until > > they work again. > > Well, they worked when I added them, so someone broke it.
I reverted my patch and added recursion detection, but I hit this nasty bug:
--------------------------------- CPU 0 Modules linked in: radeon drm autofs4 hidp rfcomm l2cap bluetooth sunrpc ip6t_REJECT ip6table_filter ip6_tables ipv6 sbs sbshc battery sg evbug ide_cd_mod cdrom snd_intel8x0 snd_ac97_codec ac97_bus serio_raw snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss e1000 snd_pcm button floppy snd_timer i2c_i801 snd soundcore i2c_core snd_page_alloc ata_generic iTCO_wdt iTCO_vendor_support pata_acpi e752x_edac edac_core pcspkr dm_snapshot dm_zero dm_mirror dm_region_hash dm_log dm_mod ata_piix libata sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci_hcd Pid: 3301, comm: pcscd Tainted: G W 2.6.30-rc1 #1036 Precision WorkStation 470 RIP: 0010:[<ffffffff803a59a2>] [<ffffffff803a59a2>] strlen+0x2/0x20 RSP: 0018:ffff880033d19c40 EFLAGS: 00010046 RAX: 0000000000000000 RBX: ffffffff807617df RCX: ffffffff807617de RDX: ffff880033d19d48 RSI: ffff880033d19c58 RDI: 5b5b5b5b5b5b5b5b RBP: ffff880033d19ca8 R08: 5b5b5b5b5b5b5b00 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000202 R12: 0000000000000000 R13: 5b5b5b5b5b5b5b5b R14: ffffffff81269b62 R15: ffff880033d19d08 FS: 0000000041b6f940(0063) GS:ffffffff80828000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000006aec88 CR3: 0000000033c02000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff4ff0 DR7: 0000000000000400 Process pcscd (pid: 3301, threadinfo ffff880033d18000, task ffff880033c48000) Stack: ffffffff803a73e5 ffffffff81269b60 ffffffff8126ab60 0000000000000004 0000000affffffff ffffffffffffffff 0000000000000000 ffff880033d19c98 0000000000000246 ffff880033d19d08 0000000000000000 0000000000000000 Call Trace: [<ffffffff803a73e5>] ? vbin_printf+0x1b5/0x2e0 [<ffffffff802b77dc>] trace_vbprintk+0xbc/0x1c0 [<ffffffff802887fe>] ? lock_acquire+0x10e/0x120 [<ffffffff802bad29>] __trace_bprintk+0x79/0x80 [<ffffffff80228ed6>] ? ftrace_call+0x5/0x2b [<ffffffff802b5dac>] ? tracing_record_cmdline+0x2c/0x100 [<ffffffff80284920>] ftrace_event_lock_acquire+0x60/0x70 [<ffffffff802887fe>] lock_acquire+0x10e/0x120 [<ffffffff8030a744>] ? dput+0x64/0x170 [<ffffffff80610336>] _spin_lock+0x36/0x70 [<ffffffff8030a744>] ? dput+0x64/0x170 [<ffffffff8039f98f>] ? _atomic_dec_and_lock+0x1f/0x50 [<ffffffff8030a744>] dput+0x64/0x170 [<ffffffff80315215>] dcache_dir_close+0x15/0x20 [<ffffffff802f8a51>] __fput+0xd1/0x230 [<ffffffff802f8f0b>] fput+0x1b/0x30 [<ffffffff802f566d>] filp_close+0x5d/0x90 [<ffffffff802f5746>] sys_close+0xa6/0x110 [<ffffffff802291af>] system_call_fastpath+0x16/0x1b Code: 01 48 83 f9 ff 0f 1f 40 00 74 0b 48 83 c7 01 0f b6 07 84 c0 75 e3 c9 31 c0 c3 c9 48 89 f8 c3 66 2e 0f 1f 84 00 00 00 00 00 31 c0 <80> 3f 00 55 48 89 e5 74 11 48 89 f8 66 90 48 83 c0 01 80 38 00 RIP [<ffffffff803a59a2>] strlen+0x2/0x20 RSP <ffff880033d19c40>
Doing an objdump:
ffffffff803a59a0 <strlen>: ffffffff803a59a0: 31 c0 xor %eax,%eax ffffffff803a59a2: 80 3f 00 cmpb $0x0,(%rdi) ffffffff803a59a5: 55 push %rbp ffffffff803a59a6: 48 89 e5 mov %rsp,%rbp ffffffff803a59a9: 74 11 je ffffffff803a59bc <strlen+0x1c>
The %rdi is: 5b5b5b5b5b5b5b5b
Either there's a bug in the vbin_printf, or we have some crazy lock->name?
TRACE_FORMAT(lock_acquire, TP_PROTO(struct lockdep_map *lock, unsigned int subclass, int trylock, int read, int check, struct lockdep_map *next_lock, unsigned long ip), TP_ARGS(lock, subclass, trylock, read, check, next_lock, ip), TP_FMT("%s%s%s", trylock ? "try " : "", read ? "read " : "", lock->name) );
I'll continue to look into this, and perhaps reboot and see what other nasties I hit.
-- Steve
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