LKML Archive on lore.kernel.org
 help / color / Atom feed
* Crashes in perf_event_ctx_lock_nested
@ 2017-10-30 22:45 Guenter Roeck
  2017-10-31 13:48 ` Peter Zijlstra
  2017-10-31 18:48 ` Crashes in perf_event_ctx_lock_nested Don Zickus
  0 siblings, 2 replies; 20+ messages in thread
From: Guenter Roeck @ 2017-10-30 22:45 UTC (permalink / raw)
  To: Thomas Gleixner; +Cc: linux-kernel, Don Zickus, Ingo Molnar

Hi Thomas,

we are seeing the following crash in v4.14-rc5/rc7 if CONFIG_HARDLOCKUP_DETECTOR
is enabled.

[    5.908021] NMI watchdog: Enabled. Permanently consumes one hw-PMU counter.
[    5.915836]
==================================================================
[    5.917325] Unsafe core_pattern used with fs.suid_dumpable=2.
[    5.917325] Pipe handler or fully qualified core dump path required.
[    5.917325] Set kernel.core_pattern before fs.suid_dumpable.
[    5.924046] udevd[147]: starting version 225
[    5.948520] BUG: KASAN: null-ptr-deref in perf_event_ctx_lock_nested.isra.71+0x22/0x89
[    5.957380] Read of size 8 at addr 0000000000000208 by task watchdog/2/21
[    5.964973]
[    5.966646] CPU: 2 PID: 21 Comm: watchdog/2 Not tainted 4.14.0-rc7 #30
[    5.973947] Hardware name: Google Eve/Eve, BIOS Google_Eve.9584.95.0 09/27/2017
[    5.982128] Call Trace:
[    5.984874]  dump_stack+0x4d/0x63
[    5.988585]  kasan_report+0x24b/0x295
[    5.992691]  ? watchdog_nmi_enable+0x12/0x12
[    5.997477]  __asan_load8+0x81/0x83
[    6.001388]  perf_event_ctx_lock_nested.isra.71+0x22/0x89
[    6.007437]  perf_event_enable+0xf/0x27
[    6.011737]  hardlockup_detector_perf_enable+0x3e/0x40
[    6.017493]  watchdog_nmi_enable+0xe/0x12
[    6.021990]  watchdog_enable+0x8c/0xc5
[    6.026195]  smpboot_thread_fn+0x27a/0x3c7
[    6.030788]  ? sort_range+0x22/0x22
[    6.034701]  kthread+0x221/0x231
[    6.038321]  ? kthread_flush_work+0x120/0x120
[    6.043204]  ret_from_fork+0x22/0x30
[    6.047207]
==================================================================
...
[    6.134561] BUG: unable to handle kernel NULL pointer dereference at 0000000000000208
[    6.143316] IP: perf_event_ctx_lock_nested.isra.71+0x22/0x89
[    6.149645] PGD 0 P4D 0 
[    6.152478] Oops: 0000 [#1] PREEMPT SMP KASAN
[    6.157350] Modules linked in:
[    6.160766] CPU: 2 PID: 21 Comm: watchdog/2 Tainted: G    B 4.14.0-rc7 #30
[    6.169422] Hardware name: Google Eve/Eve, BIOS Google_Eve.9584.95.0 09/27/2017
[    6.177583] task: ffff8803eacd1100 task.stack: ffff8803eacf8000
[    6.184206] RIP: 0010:perf_event_ctx_lock_nested.isra.71+0x22/0x89
[    6.191118] RSP: 0018:ffff8803eacffe10 EFLAGS: 00010246
[    6.196962] RAX: 0000000000000296 RBX: 0000000000000000 RCX: ffffffffa52ee8a5
[    6.204941] RDX: d8ecf37b519af800 RSI: 0000000000000003 RDI: ffffffffa6274610
[    6.212911] RBP: ffff8803eacffe30 R08: dffffc0000000000 R09: 0000000000000000
[    6.220888] R10: ffffed007d59ffa9 R11: ffffc9000044c1a1 R12: 0000000000000000
[    6.228867] R13: ffff8803eacd1100 R14: 0000000000000208 R15: ffffffffa535ce54
[    6.231476] EXT4-fs (mmcblk0p1): mounted filesystem with ordered data mode.  Opts: commit=600
[    6.237449] EXT4-fs (mmcblk0p8): mounted filesystem with ordered data mode.  Opts: (null)
[    6.255332] FS:  0000000000000000(0000) GS:ffff8803ed500000(0000) knlGS:0000000000000000
[    6.264384] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    6.270812] CR2: 0000000000000208 CR3: 0000000430615001 CR4: 00000000003606e0
[    6.278789] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    6.286761] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    6.294741] Call Trace:
[    6.297480]  perf_event_enable+0xf/0x27
[    6.301771]  hardlockup_detector_perf_enable+0x3e/0x40
[    6.307515]  watchdog_nmi_enable+0xe/0x12 
[    6.311990]  watchdog_enable+0x8c/0xc5
[    6.316176]  smpboot_thread_fn+0x27a/0x3c7
[    6.320757]  ? sort_range+0x22/0x22
[    6.324650]  kthread+0x221/0x231
[    6.328251]  ? kthread_flush_work+0x120/0x120
[    6.333114]  ret_from_fork+0x22/0x30
[    6.337107] Code: a5 e8 70 58 f6 ff 5b 5d c3 55 48 89 e5 41 56 4c 8d b7 08 02
00 00 41 55 41 54 49 89 fc 53 e8 1a e9 f5 ff 4c 89 f7 e8 8d d3 07 00 <49> 8b 9c
24 08 02 00 00 31 d2 be 01 00 00 00 48 8d bb b0 00 00
[    6.358230] RIP: perf_event_ctx_lock_nested.isra.71+0x22/0x89 RSP: ffff8803eacffe10
[    6.366779] CR2: 0000000000000208
[    6.370477] ---[ end trace ff68e1917f0a2044 ]---
[    6.383531] Kernel panic - not syncing: Fatal exception
[    6.389640] Kernel Offset: 0x24200000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)

The problem is a heisenbug - slight changes in the code, such as added logging,
can make it disappear.

I added some logging and a long msleep() in hardlockup_detector_perf_cleanup().
Here is the result:

[    0.274361] NMI watchdog: ############ hardlockup_detector_perf_init
[    0.274915] NMI watchdog: ############ hardlockup_detector_event_create(0)
[    0.277049] NMI watchdog: ############ hardlockup_detector_perf_cleanup
[    0.277593] NMI watchdog: ############ hardlockup_detector_perf_enable(0)
[    0.278027] NMI watchdog: ############ hardlockup_detector_event_create(0)
[    1.312044] NMI watchdog: ############ hardlockup_detector_perf_cleanup done
[    1.385122] NMI watchdog: ############ hardlockup_detector_perf_enable(1)
[    1.386028] NMI watchdog: ############ hardlockup_detector_event_create(1)
[    1.466102] NMI watchdog: ############ hardlockup_detector_perf_enable(2)
[    1.475536] NMI watchdog: ############ hardlockup_detector_event_create(2)
[    1.535099] NMI watchdog: ############ hardlockup_detector_perf_enable(3)
[    1.535101] NMI watchdog: ############ hardlockup_detector_event_create(3)
[    7.222816] NMI watchdog: ############ hardlockup_detector_perf_disable(0)
[    7.230567] NMI watchdog: ############ hardlockup_detector_perf_disable(1)
[    7.243138] NMI watchdog: ############ hardlockup_detector_perf_disable(2)
[    7.250966] NMI watchdog: ############ hardlockup_detector_perf_disable(3)
[    7.258826] NMI watchdog: ############ hardlockup_detector_perf_enable(1)
[    7.258827] NMI watchdog: ############ hardlockup_detector_perf_cleanup
[    7.258831] NMI watchdog: ############ hardlockup_detector_perf_enable(2)
[    7.258833] NMI watchdog: ############ hardlockup_detector_perf_enable(0)
[    7.258834] NMI watchdog: ############ hardlockup_detector_event_create(2)
[    7.258835] NMI watchdog: ############ hardlockup_detector_event_create(0)
[    7.260169] NMI watchdog: ############ hardlockup_detector_perf_enable(3)
[    7.260170] NMI watchdog: ############ hardlockup_detector_event_create(3)
[    7.494251] NMI watchdog: ############ hardlockup_detector_event_create(1)
[    8.287135] NMI watchdog: ############ hardlockup_detector_perf_cleanup done

Looks like there are a number of problems: hardlockup_detector_event_create()
creates the event data structure even if it is already created, and
hardlockup_detector_perf_cleanup() runs unprotected and in parallel to
the enable/create functions.

ALso, the following message is seen twice.

[    0.278758] NMI watchdog: Enabled. Permanently consumes one hw-PMU counter.
[    7.258838] NMI watchdog: Enabled. Permanently consumes one hw-PMU counter.

I don't offer a proposed patch since I have no idea how to best solve the
problem.

Also, is the repeated enable/disable/cleanup as part of the normal boot
really necessary ?

Thanks,
Guenter

^ permalink raw reply	[flat|nested] 20+ messages in thread

end of thread, back to index

Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-10-30 22:45 Crashes in perf_event_ctx_lock_nested Guenter Roeck
2017-10-31 13:48 ` Peter Zijlstra
2017-10-31 17:16   ` Guenter Roeck
2017-10-31 18:50     ` Don Zickus
2017-10-31 20:12       ` Guenter Roeck
2017-10-31 20:23         ` Don Zickus
2017-10-31 21:32   ` Thomas Gleixner
2017-10-31 22:11     ` Guenter Roeck
2017-11-01 18:11       ` Don Zickus
2017-11-01 18:34         ` Guenter Roeck
2017-11-01 19:46         ` [tip:core/urgent] watchdog/hardlockup/perf: Use atomics to track in-use cpu counter tip-bot for Don Zickus
2017-11-01 20:28         ` tip-bot for Don Zickus
2017-11-01 18:22       ` Crashes in perf_event_ctx_lock_nested Thomas Gleixner
2017-11-01  8:14     ` Peter Zijlstra
2017-11-01  8:26       ` Thomas Gleixner
2017-11-01 19:46     ` [tip:core/urgent] watchdog/harclockup/perf: Revert a33d44843d45 ("watchdog/hardlockup/perf: Simplify deferred event destroy") tip-bot for Thomas Gleixner
2017-11-01 20:32       ` Guenter Roeck
2017-11-01 20:52         ` Thomas Gleixner
2017-11-01 20:27     ` tip-bot for Thomas Gleixner
2017-10-31 18:48 ` Crashes in perf_event_ctx_lock_nested Don Zickus

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git