Greetings,

I got the below dmesg and the first bad commit is

git://git.open-osd.org/linux-open-osd.git bidi-mq

commit 992e60a78e1c2c6996fd55c5fb11344ad1a4c189
Author:     Boaz Harrosh <bharrosh@panasas.com>
AuthorDate: Thu Jul 19 15:22:37 2012 +0300
Commit:     Boaz Harrosh <boaz@plexistor.com>
CommitDate: Sun Mar 30 16:03:29 2014 +0300

    RFC: do_xor_speed Broken on UML do to jiffies
    
[    0.413369]    generic_sse:    70.500 MB/sec
[    0.415084] xor: using function: generic_sse (70.500 MB/sec)
[    0.416734] ------------[ cut here ]------------
[    0.418634] WARNING: CPU: 0 PID: 1 at init/main.c:708 do_one_initcall+0x174/0x18b()
[    0.420050] initcall calibrate_xor_blocks+0x0/0x1cc returned with preemption imbalance 
[    0.423371] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc8-00108-g992e60a #38
[    0.426451] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[    0.426700]  0000000000000000 ffff880000155d80 ffffffff823bd1f9 ffff880000155dc8
[    0.432082]  ffff880000155db8 ffffffff81084d37 ffffffff84684565 ffffffff846b9bc6
[    0.435342]  0000000000000000 0000000000000000 0000000000000000 ffff880000155e18
[    0.438786] Call Trace:
[    0.439766]  [<ffffffff823bd1f9>] dump_stack+0xa1/0x102
[    0.440059]  [<ffffffff81084d37>] warn_slowpath_common+0x93/0xc1
[    0.443380]  [<ffffffff84684565>] ? do_one_initcall+0x174/0x18b
[    0.446707]  [<ffffffff846b9bc6>] ? do_xor_speed+0x12d/0x12d
[    0.448950]  [<ffffffff81084df0>] warn_slowpath_fmt+0x55/0x5e
[    0.450041]  [<ffffffff846b9bc6>] ? do_xor_speed+0x12d/0x12d
[    0.453372]  [<ffffffff84684565>] do_one_initcall+0x174/0x18b
[    0.455645]  [<ffffffff846848d7>] kernel_init_freeable+0x35b/0x46d
[    0.456706]  [<ffffffff84683992>] ? do_early_param+0xd7/0xd7
[    0.460044]  [<ffffffff8239ea58>] ? rest_init+0x15c/0x15c
[    0.463372]  [<ffffffff8239ea68>] kernel_init+0x10/0x181
[    0.465550]  [<ffffffff823d890c>] ret_from_fork+0x7c/0xb0
[    0.466712]  [<ffffffff8239ea58>] ? rest_init+0x15c/0x15c
[    0.470089] ---[ end trace 5d56b560c4cace50 ]---
[    0.471938] prandom: seed boundary self test passed

git bisect start 80b612bf90a8ebdd09dff5695d0357aeb78f963e 66e810ec9fff9cf5622a8326805ef310fd5b98e7 --
git bisect good ad95c966acc03bc906dff6b875a545379680f264  # 03:08     20+      0  Merge remote-tracking branch 'linus/master' into bidi-mq
git bisect  bad 992e60a78e1c2c6996fd55c5fb11344ad1a4c189  # 03:09      0-      1  RFC: do_xor_speed Broken on UML do to jiffies
# first bad commit: [992e60a78e1c2c6996fd55c5fb11344ad1a4c189] RFC: do_xor_speed Broken on UML do to jiffies
git bisect good ad95c966acc03bc906dff6b875a545379680f264  # 03:20     60+      0  Merge remote-tracking branch 'linus/master' into bidi-mq
git bisect  bad 80b612bf90a8ebdd09dff5695d0357aeb78f963e  # 03:20      0-     19  {TODO} bsg: remove bogus (and fatal) check in bsg_register_queue
git bisect good 981e893ed537cbaa08f8089d480db4165e6d71c0  # 03:31     60+      0  Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 201544be8c37dffbf069bb5fc9edb5674f8c1754  # 03:36     60+      0  Add linux-next specific files for 20140328


This script may reproduce the error.

-----------------------------------------------------------------------------
#!/bin/bash

kernel=$1

kvm=(
	qemu-system-x86_64 -cpu kvm64 -enable-kvm
	-kernel $kernel
	-smp 2
	-m 256M
	-net nic,vlan=0,macaddr=00:00:00:00:00:00,model=virtio
	-net user,vlan=0
	-net nic,vlan=1,model=e1000
	-net user,vlan=1
	-boot order=nc
	-no-reboot
	-watchdog i6300esb
	-serial stdio
	-display none
	-monitor null
)

append=(
	debug
	sched_debug
	apic=debug
	ignore_loglevel
	sysrq_always_enabled
	panic=10
	prompt_ramdisk=0
	earlyprintk=ttyS0,115200
	console=ttyS0,115200
	console=tty0
	vga=normal
	root=/dev/ram0
	rw
)

"${kvm[@]}" --append "${append[*]}"
-----------------------------------------------------------------------------

Thanks,
Fengguang