Message-ID: <1337880914.13348.189.camel@gandalf.stny.rr.com>
Date:	Thu, 24 May 2012 13:35:14 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Dave Jones <davej@...hat.com>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: tracing ring_buffer_resize oops.

On Thu, 2012-05-24 at 13:22 -0400, Dave Jones wrote:
> On Thu, May 24, 2012 at 12:19:58PM -0400, Steven Rostedt wrote:
>  > On Thu, 2012-05-24 at 12:01 -0400, Dave Jones wrote:
>  > > Hit this while trying to configure the irq-tracer.
>  > > I ran cat trace before doing a "echo 0 > tracing_on" by mistake.
>  > > Shot myself in the foot, but it still shouldn't oops.
>  > > 
>  > 
>  > Hi Dave,
>  > 
>  > Thanks for reporting. Could you try this patch to see if it fixes it for
>  > you.
>  > 
>  > http://groups.google.com/group/linux.kernel/msg/4294e8d564d66997?dmode=source
>  > 
>  > Below is the patch again, as the one in the link has GPG tags that might
>  > screw with patch.
> 
> hmm, this time I didn't even get past 'echo irqsoff > current_tracer'

This looks different. In fact, I had the similar bug but! (see below)

> 
> 	Dave
> 
> [ 1013.243754] BUG: unable to handle kernel NULL pointer dereference at 0000000000000002
> [ 1013.272665] IP: [<ffff880145cc0000>] 0xffff880145cbffff
> [ 1013.285186] PGD 1401b2067 PUD 14324c067 PMD 0 
> [ 1013.298832] Oops: 0010 [#1] PREEMPT SMP 
> [ 1013.310600] CPU 2 
> [ 1013.317904] Modules linked in: ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables crc32c_intel ghash_clmulni_intel microcode usb_debug serio_raw pcspkr iTCO_wdt i2c_i801 iTCO_vendor_support e1000e nfsd nfs_acl auth_rpcgss lockd sunrpc i915 video i2c_algo_bit drm_kms_helper drm i2c_core [last unloaded: scsi_wait_scan]
> [ 1013.401848] 
> [ 1013.407399] Pid: 112, comm: kworker/2:1 Not tainted 3.4.0+ #30 
> [ 1013.437943] RIP: 8eb8:[<ffff88014630a000>]  [<ffff88014630a000>] 0xffff880146309fff

The RIP is meaningless.

> [ 1013.459871] RSP: ffffffff8165e919:ffff88014780f408  EFLAGS: 00010046
> [ 1013.477909] RAX: 0000000000000001 RBX: ffffffff81104020 RCX: 0000000000000000
> [ 1013.499458] RDX: ffff880148008ea8 RSI: ffffffff8131ef40 RDI: ffffffff82203b20
> [ 1013.521612] RBP: ffffffff81005751 R08: 0000000000000000 R09: 0000000000000000
> [ 1013.543121] R10: ffffffff82cdc318 R11: 0000000000000000 R12: ffff880145cc0000
> [ 1013.564614] R13: ffff880148008eb8 R14: 0000000000000002 R15: ffff88014780cb40
> [ 1013.586108] FS:  0000000000000000(0000) GS:ffff880148000000(0000) knlGS:0000000000000000
> [ 1013.609458] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 1013.627420] CR2: 0000000000000002 CR3: 0000000141f10000 CR4: 00000000001407e0
> [ 1013.649051] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 1013.670724] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 1013.692376] Process kworker/2:1 (pid: 112, threadinfo ffff88013fe0e000, task ffff88014020a6a0)
> [ 1013.717028] Stack:
> [ 1013.724131]  ffff88014780f570 ffff880145cc0000 0000400000004000 0000000000000000
> [ 1013.745918]  cccccccccccccccc ffff88014780cca8 ffffffff811072bb ffffffff81651627
> [ 1013.767870]  ffffffff8118f8a7 ffffffff811072bb ffffffff81f2b6c5 ffffffff81f11bdb
> [ 1013.790021] Call Trace:
> [ 1013.800701] Code: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a <e7> d7 64 81 ff ff ff ff 01 00 00 00 00 00 00 00 65 d9 64 81 ff 
> [ 1013.861443] RIP  [<ffff88014630a000>] 0xffff880146309fff
> [ 1013.884466]  RSP <ffff88014780f408>
> [ 1013.901507] CR2: 0000000000000002
> [ 1013.918628] ---[ end trace d0e6e5741aaf56ac ]---
> [ 1013.940297] BUG: sleeping function called from invalid context at kernel/rwsem.c:20
> [ 1013.972340] in_atomic(): 0, irqs_disabled(): 1, pid: 112, name: kworker/2:1
> [ 1014.001470] INFO: lockdep is turned off.
> [ 1014.021285] irq event stamp: 146784
> [ 1014.039375] hardirqs last  enabled at (146783): [<ffffffff8165b4f4>] paranoid_restore+0x10/0x66
> [ 1014.074744] hardirqs last disabled at (146784): [<ffffffff8165b380>] int3+0x10/0x40
> [ 1014.106164] softirqs last  enabled at (146418): [<ffffffff81052054>] __do_softirq+0x144/0x3d0
> [ 1014.141604] softirqs last disabled at (146407): [<ffffffff81663e4c>] call_softirq+0x1c/0x30
> [ 1014.174829] Pid: 112, comm: kworker/2:1 Tainted: G      D      3.4.0+ #30
> [ 1014.204753] Call Trace:
> [ 1014.220719]  <#DB>  [<ffffffff810b3eb0>] ? print_irqtrace_events+0xd0/0xe0
> [ 1014.251033]  [<ffffffff8107f5c0>] __might_sleep+0x140/0x1f0
> [ 1014.276482]  [<ffffffff81657fc6>] down_read+0x26/0x93
> [ 1014.301499]  [<ffffffff810624e4>] exit_signals+0x24/0x130
> [ 1014.326264]  [<ffffffff8104e95c>] do_exit+0xbc/0xb70
> [ 1014.348709]  [<ffffffff8104b8b3>] ? kmsg_dump+0x83/0x2b0
> [ 1014.373726]  [<ffffffff8164d5e3>] ? printk+0x61/0x63
> [ 1014.396878]  [<ffffffff8165c007>] oops_end+0x97/0xe0
> [ 1014.420306]  [<ffffffff8164cece>] no_context+0x258/0x283
> [ 1014.446640]  [<ffffffff8164d0bd>] __bad_area_nosemaphore+0x1c4/0x1e3
> [ 1014.474615]  [<ffffffff8164d0ef>] bad_area_nosemaphore+0x13/0x15
> [ 1014.505249]  [<ffffffff8165e540>] do_page_fault+0x3c0/0x4b0
> [ 1014.531368]  [<ffffffff8106f708>] ? __kernel_text_address+0x58/0x80
> [ 1014.560247]  [<ffffffff810057cf>] ? print_context_stack+0x8f/0xf0
> [ 1014.589070]  [<ffffffff810860f1>] ? get_parent_ip+0x11/0x50
> [ 1014.614948]  [<ffffffff8165b613>] ? error_sti+0x5/0x6
> [ 1014.641105]  [<ffffffff810b0b38>] ? trace_hardirqs_off_caller+0x28/0xc0
> [ 1014.671882]  [<ffffffff81005751>] ? print_context_stack+0x11/0xf0
> [ 1014.700148]  [<ffffffff8131ac5d>] ? trace_hardirqs_off_thunk+0x3a/0x3c
> [ 1014.730928]  [<ffffffff81005751>] ? print_context_stack+0x11/0xf0
> [ 1014.759028]  [<ffffffff8165b42f>] page_fault+0x1f/0x30
> [ 1014.784924]  [<ffffffff81005751>] ? print_context_stack+0x11/0xf0
> [ 1014.812910]  [<ffffffff81104020>] ? __add_hash_entry+0x90/0x90
> [ 1014.840108]  [<ffffffff8131ef40>] ? bsearch+0x60/0x90
> [ 1014.864867]  [<ffffffff81104020>] ? __add_hash_entry+0x90/0x90
> [ 1014.891647]  [<ffffffff8165e919>] ? sub_preempt_count+0x9/0xd0
> [ 1014.918212]  [<ffffffff8165b466>] ? paranoid_exit+0x6/0x1b
> [ 1014.942506]  [<ffffffff810b0b38>] ? trace_hardirqs_off_caller+0x28/0xc0
> [ 1014.971053]  [<ffffffff8131ac5d>] ? trace_hardirqs_off_thunk+0x3a/0x3c
> [ 1014.999788]  [<ffffffff81104020>] ? __add_hash_entry+0x90/0x90
> [ 1015.026354]  [<ffffffff8165e919>] ? sub_preempt_count+0x9/0xd0
> [ 1015.052818]  [<ffffffff8165b466>] ? paranoid_exit+0x6/0x1b

Hmm, I wonder if this is the break point change :-/

Do you have NMIs enabled? I didn't have 'paranoid_exit' in my backtrace
when I saw the bug.

I saw this but after doing a cp .config /tmp; make mrproper;
cp /tmp/.config .;  make

The problem went away.

I'll start running a bunch of high stress tests using NMIs again (on
this box) and see if I can force this to happen again :-/

-- Steve


> [ 1015.077099]  [<ffffffff81005751>] ? print_context_stack+0x11/0xf0
> [ 1015.103546]  [<ffffffff8165e91e>] ? sub_preempt_count+0xe/0xd0
> [ 1015.131390]  <<EOE>> 
> [ 1015.145014] BUG: unable to handle kernel paging request at fffffffffffffff8
> [ 1015.169954] IP: [<ffffffff81072ee1>] kthread_data+0x11/0x20
> [ 1015.190713] PGD 1c0d067 PUD 1c0e067 PMD 0 
> [ 1015.207586] Oops: 0000 [#2] PREEMPT SMP 
> [ 1015.224452] CPU 2 
> [ 1015.236313] Modules linked in: ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables crc32c_intel ghash_clmulni_intel microcode usb_debug serio_raw pcspkr iTCO_wdt i2c_i801 iTCO_vendor_support e1000e nfsd nfs_acl auth_rpcgss lockd sunrpc i915 video i2c_algo_bit drm_kms_helper drm i2c_core [last unloaded: scsi_wait_scan]
> [ 1015.339235] 


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