Greetings,

I find the below dmesg in upstream and linux-next.

[    2.456884] Testing tracer branch: 
[    2.458281] ------------[ cut here ]------------
[    2.459813] WARNING: at /c/kernel-tests/src/tip/kernel/lockdep.c:3537 check_flags+0xb7/0x1b0()
[    2.460000] Hardware name: Bochs
[    2.460000] Pid: 3, comm: ksoftirqd/0 Not tainted 3.9.0-rc4-03252-g8b473e1 #58
[    2.460000] Call Trace:

[    2.460000]  [<ffffffff81073cdf>] warn_slowpath_common+0xaf/0xd0
[    2.460000]  [<ffffffff81073dda>] warn_slowpath_null+0x1a/0x20
[    2.460000]  [<ffffffff810e14f7>] check_flags+0xb7/0x1b0
[    2.460000]  [<ffffffff810e2682>] lock_is_held+0x62/0xc0
[    2.460000]  [<ffffffff810c938c>] __might_sleep+0x3c/0x3b0
[    2.460000]  [<ffffffff81082404>] run_ksoftirqd+0xd4/0x130
[    2.460000]  [<ffffffff810bec5c>] smpboot_thread_fn+0x25c/0x2e0
[    2.460000]  [<ffffffff810bea00>] ? lg_global_unlock+0x40/0x40
[    2.460000]  [<ffffffff810b210b>] kthread+0xfb/0x110
[    2.460000]  [<ffffffff810b2010>] ? insert_kthread_work+0x120/0x120
[    2.460000]  [<ffffffff81825c7a>] ret_from_fork+0x7a/0xb0
[    2.460000]  [<ffffffff810b2010>] ? insert_kthread_work+0x120/0x120
[    2.460000] ---[ end trace 3af7e87d98c6254d ]---

Bisecting for "__might_sleep" and the first bad commit is

commit 965a002b4f1a458c5dcb334ec29f48a0046faa25
Author: Paul E. McKenney <paul.mckenney@linaro.org>
Date:   Sat Jun 18 09:55:39 2011 -0700

    rcu: Make TINY_RCU also use softirq for RCU_BOOST=n
    
    This patch #ifdefs TINY_RCU kthreads out of the kernel unless RCU_BOOST=y,
    thus eliminating context-switch overhead if RCU priority boosting has
    not been configured.
    
    Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

But note that its parent commit 385680a9487d2f85382ad6d74e2a15837e47bfd9
is not really clean and has this dmesg instead:

[    2.592748] Testing tracer wakeup_rt: PASSED
[    2.936495] Testing tracer branch: 
[    2.940281] ------------[ cut here ]------------
[    2.941194] WARNING: at /c/wfg/mm/kernel/lockdep.c:3363 check_flags.part.31+0xaf/0x1c0()
[    2.942593] Hardware name: Bochs
[    2.943199] Pid: 0, comm: swapper Not tainted 3.1.0-rc8-00019-g385680a #99
[    2.944234] Call Trace:
[    2.944234]  <IRQ>  [<ffffffff81050b9e>] warn_slowpath_common+0x9e/0xd0
[    2.944234]  [<ffffffff81050caa>] warn_slowpath_null+0x1a/0x20
[    2.944234]  [<ffffffff8109fddf>] check_flags.part.31+0xaf/0x1c0
[    2.944234]  [<ffffffff810a49a9>] lock_acquire+0x119/0x230
[    2.944234]  [<ffffffff810657c7>] run_timer_softirq+0x217/0x8a0
[    2.944234]  [<ffffffff81065751>] ? run_timer_softirq+0x1a1/0x8a0
[    2.944234]  [<ffffffff810655a0>] ? ftrace_raw_output_itimer_expire+0x160/0x160
[    2.944234]  [<ffffffff8105c190>] __do_softirq+0x1c0/0x5c0
[    2.944234]  [<ffffffff815b8f7a>] call_softirq+0x1a/0x30
[    2.944234]  [<ffffffff81006465>] do_softirq+0x165/0x290
[    2.944234]  [<ffffffff8105c967>] irq_exit+0xb7/0x130
[    2.944234]  [<ffffffff810237d7>] smp_apic_timer_interrupt+0x77/0xb0
[    2.944234]  [<ffffffff815b8971>] apic_timer_interrupt+0x71/0x80
[    2.944234]  <EOI>  [<ffffffff810e1e75>] ? ftrace_likely_update+0xc5/0x230
[    2.944234]  [<ffffffff810a045d>] ? trace_hardirqs_off+0xd/0x10
[    2.944234]  [<ffffffff8102bdab>] ? native_safe_halt+0xb/0x10
[    2.944234]  [<ffffffff8100f893>] default_idle+0x7d3/0x810
[    2.944234]  [<ffffffff8100131c>] cpu_idle+0x14c/0x160
[    2.944234]  [<ffffffff815922f3>] rest_init+0xe7/0xf4
[    2.944234]  [<ffffffff8159220c>] ? csum_partial_copy_generic+0x16c/0x16c
[    2.944234]  [<ffffffff81c33f15>] start_kernel+0x4f4/0x4ff
[    2.944234]  [<ffffffff81c33000>] ? vsyscall_gtod_data+0xf80/0xf80
[    2.944234]  [<ffffffff81c33000>] ? vsyscall_gtod_data+0xf80/0xf80
[    2.944234]  [<ffffffff81c33169>] x86_64_start_reservations+0x166/0x16a
[    2.944234]  [<ffffffff81c333dd>] x86_64_start_kernel+0x270/0x27f
[    2.944234] ---[ end trace 6d450e935ee1897c ]---
[    2.944234] possible reason: unannotated irqs-on.
[    2.944234] irq event stamp: 10085
[    2.944234] hardirqs last  enabled at (10084): [<ffffffff815b6892>] _raw_spin_unlock_irq+0x32/0x80
[    2.944234] hardirqs last disabled at (10085): [<ffffffff810e1e37>] ftrace_likely_update+0x87/0x230
[    2.944234] softirqs last  enabled at (10076): [<ffffffff8105c8a7>] irq_enter+0x87/0x90
[    2.944234] softirqs last disabled at (10077): [<ffffffff815b8f7a>] call_softirq+0x1a/0x30
[    3.040274] PASSED
[    3.041998] HugeTLB registered 2 MB page size, pre-allocated 0 pages


git bisect start v3.2 v3.1 --
git bisect  bad 68d99b2c8efcb6ed3807a55569300c53b5f88be5  # 10:10      0-  Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
git bisect good efb8d21b2c6db3497655cc6a033ae8a9883e4063  # 10:18     27+  Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
git bisect  bad 8686a0e200419322654a75155e2e6f80346a1297  # 10:22      0-  Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 33bc95513c801b1637b6fb925155fb794b5da4f0  # 10:27     27+  staging: brcm80211: remove 'default n' from Kconfig
git bisect good 4d8daa6b77d0697ea19b9c4f704be9b26d76fb36  # 10:34     27+  staging: brcm80211: cleaned up struct brcms_bss_cfg
git bisect good 982653009b883ef1529089e3e6f1ae2fee41cbe2  # 10:38     27+  Merge branch 'core-iommu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 47724df3375bf0cf652039ab6b7ded29fe877de6  # 10:43     27+  Merge branch 'tip/perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core
git bisect  bad 048b718029033af117870d3da47da12995be14a3  # 10:52      0-  Merge branch 'rcu/next' of git://github.com/paulmckrcu/linux into core/rcu
git bisect  bad e5177ec77d503636d0b609671c9d408b981add17  # 10:56      0-  rcu: Not necessary to pass rcu_read_lock_held() to rcu_dereference_protected()
git bisect good 8008e129dc90ff4f7a56cb033d6bd042afe3ed52  # 11:00     27+  rcu: Drive configuration directly from SMP and PREEMPT
git bisect good e0f23060adfa3f27beaa7918eff70258b88471b6  # 11:04     27+  rcu: Update comments to reflect softirqs vs. kthreads
git bisect  bad 965a002b4f1a458c5dcb334ec29f48a0046faa25  # 11:10      0-  rcu: Make TINY_RCU also use softirq for RCU_BOOST=n
git bisect good 385680a9487d2f85382ad6d74e2a15837e47bfd9  # 11:20     27+  rcu: Add event-trace markers to TREE_RCU kthreads
git bisect good 385680a9487d2f85382ad6d74e2a15837e47bfd9  # 11:24     81+  rcu: Add event-trace markers to TREE_RCU kthreads
git bisect  bad 1d995963014cc2a847f9e18d972a9e845b5c27cd  # 11:24      0-  Merge remote-tracking branch 'stable/master'
git bisect  bad 9e895ace5d82df8929b16f58e9f515f6d54ab82d  # 11:24      0-  Linux 3.10-rc7
git bisect  bad e1a86578747376f08985627c84df088a5d0d1e92  # 11:27      9-  Add linux-next specific files for 20130621

Thanks,
Fengguang