Greetings,

0day kernel testing robot got the below dmesg and the first bad commit is

git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git initramfs

commit 8dd45530cb1353fbd058d42a3e6d32bde811429b
Author:     Mimi Zohar <zohar@linux.vnet.ibm.com>
AuthorDate: Tue Dec 23 18:27:34 2014 -0500
Commit:     Mimi Zohar <zohar@linux.vnet.ibm.com>
CommitDate: Fri Jan 30 13:42:29 2015 -0500

    initramfs: separate reading cpio method from header
    
    In preparation for adding xattr support, read the CPIO method
    separately from the rest of the header.
    
    Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

+-----------------------------------------------------+------------+------------+------------+
|                                                     | 7bea7ff67e | 8dd45530cb | 870a4dc46e |
+-----------------------------------------------------+------------+------------+------------+
| boot_successes                                      | 60         | 0          | 0          |
| boot_failures                                       | 0          | 20         | 11         |
| Kernel_panic-not_syncing:junk_in_compressed_archive | 0          | 20         | 11         |
| backtrace:populate_rootfs                           | 0          | 20         | 11         |
| backtrace:kernel_init_freeable                      | 0          | 20         | 11         |
+-----------------------------------------------------+------------+------------+------------+

[    0.157126] pci 0000:00:01.0: Activating ISA DMA hang workarounds
[    0.157648] pci 0000:00:02.0: Video device with shadowed ROM
[    0.158116] PCI: CLS 0 bytes, default 64
[    0.158459] Kernel panic - not syncing: junk in compressed archive
[    0.158932] CPU: 0 PID: 1 Comm: swapper Not tainted 3.19.0-rc4-g8dd4553 #5
[    0.159485] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[    0.160116]  d2121770 d2121770 d2045edc c4d34984 d2045ef4 c4d33ea5 c5036200 d2121770
[    0.160116]  c5036200 c51e2b1f d2045f10 c51e2b44 c4f58381 c4f12230 d2121770 c5036200
[    0.160116]  c51e2b1f d2045f84 c460041e 000000d0 c4f1c126 c51e2b1f c51e14ba c502d814
[    0.160116] Call Trace:
[    0.160116]  [<c4d34984>] dump_stack+0x16/0x18
[    0.160116]  [<c4d33ea5>] panic+0x87/0x1a2
[    0.160116]  [<c51e2b1f>] ? do_format+0x71/0x71
[    0.160116]  [<c51e2b44>] populate_rootfs+0x25/0xee
[    0.160116]  [<c51e2b1f>] ? do_format+0x71/0x71
[    0.160116]  [<c460041e>] do_one_initcall+0x7e/0x1d0
[    0.160116]  [<c51e2b1f>] ? do_format+0x71/0x71
[    0.160116]  [<c51e14ba>] ? repair_env_string+0x12/0x54
[    0.160116]  [<c51e1b8a>] kernel_init_freeable+0xdb/0x158
[    0.160116]  [<c4d326cb>] kernel_init+0xb/0xe0
[    0.160116]  [<c464caa2>] ? schedule_tail+0x12/0x60
[    0.160116]  [<c4d47560>] ret_from_kernel_thread+0x20/0x30
[    0.160116]  [<c4d326c0>] ? rest_init+0xa0/0xa0

Elapsed time: 5
qemu-system-x86_64 -cpu kvm64 -enable-kvm -kernel /kernel/i386-randconfig-j1-01312211/8dd45530cb1353fbd058d42a3e6d32bde811429b/vmlinuz-3.19.0-rc4-g8dd4553 -append 'hung_task_panic=1 earlyprintk=ttyS0,115200 debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal  root=/dev/ram0 rw link=/kbuild-tests/run-queue/kvm/i386-randconfig-j1-01312211/linux-devel:devel-jaketown-smoke-201501312324:8dd45530cb1353fbd058d42a3e6d32bde811429b:bisect-linux-4/.vmlinuz-8dd45530cb1353fbd058d42a3e6d32bde811429b-20150201141752-18-ivb41 branch=linux-devel/devel-jaketown-smoke-201501312324 BOOT_IMAGE=/kernel/i386-randconfig-j1-01312211/8dd45530cb1353fbd058d42a3e6d32bde811429b/vmlinuz-3.19.0-rc4-g8dd4553 drbd.minor_count=8'  -initrd /kernel-tests/initrd/quantal-core-i386.cgz -m 320 -smp 2 -net nic,vlan=1,model=e1000 -net user,vlan=1 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -pidfile /dev/shm/kboot/pid-quantal-ivb41-108 -serial file:/dev/shm/kboot/serial-quantal-ivb41-108 -daemonize -display none -monitor null 

git bisect start 870a4dc46e425037bd3ffacbb683e845a34fceda a6391a924cf5a16761ccd6b45094a7d5b9aeebac --
git bisect good 87155b7311bfec75b590b823b11f77adf2a16412  # 11:42     20+      0  tpm: merge duplicate transmit_cmd() functions
git bisect good 3eda7d0ea3a0365aa72a2007f9450f314d92f065  # 11:52     20+      0  tpm/tpm_i2c_stm_st33: Change tpm_i2c_stm_st33.h to tpm_stm_st33.h
git bisect good 9d5a5f65fcabb876cb0092901d56627bd5cbfc44  # 12:28     20+      0  Merge branch 'smack-for-3.20-rebased' of git://git.gitorious.org/smack-next/kernel into next
git bisect good 90200f19160734feceb92a3a054864c340242699  # 12:29     20+      0  Merge branch 'smack-for-3.20-rebased' of git://git.gitorious.org/smack-next/kernel into next
git bisect good 7bea7ff67e0cbb30f53ebee7194e238491ddeaab  # 13:41     20+      0  ima: /proc/keys is now mandatory
git bisect  bad 8dd45530cb1353fbd058d42a3e6d32bde811429b  # 14:18      0-     20  initramfs: separate reading cpio method from header
# first bad commit: [8dd45530cb1353fbd058d42a3e6d32bde811429b] initramfs: separate reading cpio method from header
git bisect good 7bea7ff67e0cbb30f53ebee7194e238491ddeaab  # 14:22     60+      0  ima: /proc/keys is now mandatory
# extra tests with DEBUG_INFO
git bisect  bad 8dd45530cb1353fbd058d42a3e6d32bde811429b  # 14:24      0-     60  initramfs: separate reading cpio method from header
# extra tests on HEAD of linux-devel/devel-jaketown-smoke-201501312324
# extra tests on tree/branch integrity/initramfs
# extra tests on tree/branch linus/master
git bisect good 788807d7ca3821b5ea835a588a52d55631c17e18  # 16:31     60+      0  Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
# extra tests on tree/branch next/master
git bisect good 827e3bdf1bb2401c1a1e5586eb3977d228d298b2  # 17:10     60+      0  Add linux-next specific files for 20150130


This script may reproduce the error.

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

kernel=$1
initrd=quantal-core-i386.cgz

wget --no-clobber https://github.com/fengguang/reproduce-kernel-bug/raw/master/initrd/$initrd

kvm=(
	qemu-system-x86_64
	-cpu kvm64
	-enable-kvm
	-kernel $kernel
        -initrd $initrd
	-m 320
	-smp 2
	-net nic,vlan=1,model=e1000
	-net user,vlan=1
	-boot order=nc
	-no-reboot
	-watchdog i6300esb
	-rtc base=localtime
	-serial stdio
	-display none
	-monitor null 
)

append=(
	hung_task_panic=1
	earlyprintk=ttyS0,115200
	debug
	apic=debug
	sysrq_always_enabled
	rcupdate.rcu_cpu_stall_timeout=100
	panic=-1
	softlockup_panic=1
	nmi_watchdog=panic
	oops=panic
	load_ramdisk=2
	prompt_ramdisk=0
	console=ttyS0,115200
	console=tty0
	vga=normal
	root=/dev/ram0
	rw
	drbd.minor_count=8
)

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

Thanks,
Fengguang