On Mon, Dec 14, 2015 at 02:36:13PM +0100, Boris Brezillon wrote: > On Mon, 14 Dec 2015 21:12:47 +0800 > Fengguang Wu wrote: > > > On Mon, Dec 14, 2015 at 02:04:33PM +0100, Boris Brezillon wrote: > > > On Mon, 14 Dec 2015 13:58:09 +0100 > > > Boris Brezillon wrote: > > > > > > > On Mon, 14 Dec 2015 20:47:19 +0800 > > > > Fengguang Wu wrote: > > > > > > > > > On Mon, Dec 14, 2015 at 11:42:44AM +0100, Boris Brezillon wrote: > > > > > > Hi Fengguang, > > > > > > > > > > > > On Mon, 14 Dec 2015 14:45:37 +0800 > > > > > > Fengguang Wu wrote: > > > > > > > > > > > > > Hi Boris, > > > > > > > > > > > > > > On Sun, Dec 13, 2015 at 09:50:43PM +0100, Boris Brezillon wrote: > > > > > > > > Hi Fengguang, > > > > > > > > > > > > > > > > On Sun, 13 Dec 2015 09:49:17 +0800 > > > > > > > > Fengguang Wu wrote: > > > > > > > > > > > > > > > > > Hi Boris, > > > > > > > > > > > > > > > > > > FYI, this happened when merging your branch, which indicates possible > > > > > > > > > conflicts with other developer's patches or the new RC release. > > > > > > > > > > > > > > > > Is this boot test also run on my bbrezillon-0day/nand/layering-rework > > > > > > > > branch (before merging it into devel-spot), and if it is, do you see the > > > > > > > > same error? > > > > > > > > > > > > > > The bisect tests bbrezillon-0day/nand/layering-rework, however it's > > > > > > > fine there. > > > > > > > > > > > > > > > Is the devel-spot-201512102358 tag publicly accessible? If it's not, > > > > > > > > > > > > > > Nope. > > > > > > > > > > > > > > > could you push it somewhere (or give me a way to generate it by > > > > > > > > pulling the relevant branches), so that I can investigate on this bug? > > > > > > > > > > > > > > Or it may be more convenient to check linux-next first? > > > > > > > > > > > > > > FYI, the merged branches in devel-spot-201512102358 are: > > > > > > > > > > > > > > af8fc33 Merge 'bbrezillon-0day/nand/layering-rework' into devel-spot-201512102358 > > > > > > > acfc1de Merge 'linux-review/Maury-Markowitz/renaming-NTSC-file-because-it-doesnt-actually-use-8VSV-updating-channel-listings-add-channel-numbers/20151210-210449' into devel-spot-201512102358 > > > > > > > fb9daac Merge 'fdmanana/integration-4.4' into devel-spot-201512102358 > > > > > > > 1b30725 Merge 'fdmanana/for-chris-4.4' into devel-spot-201512102358 > > > > > > > 83f2246 Merge 'arm-integrator/realview-defconfig' into devel-spot-201512102358 > > > > > > > 03df745 Merge 'arm-integrator/realview-multiplatform-base' into devel-spot-201512102358 > > > > > > > d2aea29 Merge 'linux-review/Arnd-Bergmann/i2c-allow-building-emev2-without-slave-mode-again/20151210-211642' into devel-spot-201512102358 > > > > > > > e2f041d Merge 'arm-integrator/realview-base-armsoc' into devel-spot-201512102358 > > > > > > > 5c46550 Merge 'linux-review/Bert-Kenward/sfc-only-use-RSS-filters-if-we-re-using-RSS/20151210-213247' into devel-spot-201512102358 > > > > > > > d07f80f Merge 'sound/test/hdmi-jack' into devel-spot-201512102358 > > > > > > > 540f8b7 Merge 'sound/topic/hdmi-jack' into devel-spot-201512102358 > > > > > > > 9111fa0 Merge 'linux-review/matrandg-cisco-com/tc358743-Use-local-array-with-fixed-size-in-i2c-write/20151210-214154' into devel-spot-201512102358 > > > > > > > 3d81ef9 Merge 'linux-review/matrandg-cisco-com/tc358743-Print-timings-only-when-debug-level-is-set/20151210-220321' into devel-spot-201512102358 > > > > > > > 122e43c Merge 'bbrezillon-0day/nand/ecclayout-squashed' into devel-spot-201512102358 > > > > > > > e0572f8 Merge 'wireless-drivers-next/pending' into devel-spot-201512102358 > > > > > > > dc5d9c9 Merge 'linux-review/Geliang-Tang/list-introduce-list_is_first/20151210-222552' into devel-spot-201512102358 > > > > > > > 289e2a8 Merge 'linux-review/Arnd-Bergmann/staging-davinci_vfpe-allow-modular-build/20151210-223348' into devel-spot-201512102358 > > > > > > > d74c50d Merge 'linux-review/Damien-Horsley/Add-driver-for-Pistachio-internal-DAC/20151210-224304' into devel-spot-201512102358 > > > > > > > ee3c58b Merge 'cryptodev/master' into devel-spot-201512102358 > > > > > > > d390f7d Merge 'linux-review/John-Garry/hisi_sas-use-platform_get_irq/20151210-224851' into devel-spot-201512102358 > > > > > > > de31f5d Merge 'linux-review/Mike-Marciniszyn/staging-rdma-hfi1-add-definitions-for-OPA-traps/20151210-230158' into devel-spot-201512102358 > > > > > > > 5618568 Merge 'linux-review/Andrei-Emeltchenko/Bluetooth-h5-Do-not-initialize-Configuration-field/20151210-230440' into devel-spot-201512102358 > > > > > > > 759aa32 Merge 'linux-review/Moritz-K-nig/staging-COMEDI-checkpatch-pl-cleanups-in-comedi-h/20151210-230707' into devel-spot-201512102358 > > > > > > > 2edcbb4 Merge 'linux-review/Andy-Shevchenko/net-hns-annotate-IO-address-space-properly/20151210-232510' into devel-spot-201512102358 > > > > > > > 0f51fdd Merge 'integrity/next-kexec' into devel-spot-201512102358 > > > > > > > b32bcbc Merge 'dm/dm-4.5' into devel-spot-201512102358 > > > > > > > ea297f5 Merge 'linux-review/Mathieu-Desnoyers/thread_local_abi-system-call-caching-current-CPU-number-x86/20151210-234242' into devel-spot-201512102358 > > > > > > > 52bc163 Merge 'linux-review/yegorslists-googlemail-com/USB-serial-option-add-support-for-Quectel-UC20/20151210-234659' into devel-spot-201512102358 > > > > > > > 797cc7c Merge 'linux-review/Andy-Shevchenko/staging-rtl8188eu-provide-an-absolute-path-to-include-folder/20151210-234752' into devel-spot-201512102358 > > > > > > > 23d8b49 Merge 'omap-dss2/for-next' into devel-spot-201512102358 > > > > > > > 88a768f 0day base guard for 'devel-spot-201512102358' > > > > > > > 527e931 Linux 4.4-rc4 > > > > > > > > > > > > > > > > > > > > > > > > > linux-next/master also has the problem. > > > > > > > > > > > > > > > > Okay. You mean linux-next/master alone, or after merging my branch into > > > > > > > > linux-next/master? > > > > > > > > > > > > > > It's stand alone linux-next/master as indicated by the bisect log. > > > > > > > Does it include any of your patches? > > > > > > > > > > > > I tried to boot the next-20151214 build, before [1] and after [2] > > > > > > merging my nand/layering-rework branch merged into it, and both are > > > > > > booting fine. > > > > > > > > > > Are you using the emailed kconfig? I'd not recommend try the below > > > > > step if cannot even reproduce the issue in linux-next. > > > > > > > > Yes, I did use the config you attached in your email + the script your > > > > pasted to boot the kernel with qemu, and linux-next/master boots > > > > correctly. > > > > As answered in the other email I just sent, I managed to reproduce the > > > > bug you're pointing after merging both > > > > bbrezillon-0day/nand/ecclayout-squashed and > > > > bbrezillon-0day/nand/layering-rework into linus' 4.4-rc4. > > > > > > > > > > > > > > FYI, below is the patch I used to fix the bug, but I'd be interested in > > > reproducing the problem you've seen on linux-next/master. Did you, by > > > any chance, keep the branch/tag you used to trigger this bug on > > > linux-next? > > > > Yes. Bisect log shows that these 2 commits both have the bug: > > > > # extra tests on tree/branch linus/master > > git bisect bad a80c47daa818ead2644917d72ff2a934dd64fd16 # 03:36 0- 1 Merge tag 'sound-4.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound > > I just tested this commit, and it works fine on my side... > Could you test it again? You are so quick! Yes sorry, it has an independent NULL pointer bug which shows up occasionally: [ 12.547319] IRQ15 -> 0:15 [ 12.548468] .................................... done. [ 12.549756] Using IPI No-Shortcut mode [ 12.551116] page_owner is disabled [ 12.560504] Btrfs loaded, assert=on [ 12.561866] Key type encrypted registered [ 12.572811] hd: no drives specified - use hd=cyl,head,sectors on kernel command line [ 12.579517] BIOS EDD facility v0.16 2004-Jun-25, 6 devices found [ 12.581027] ALSA device list: [ 12.616063] #0: Dummy 1 [ 12.621496] #1: Loopback 1 [ 12.622959] Freeing unused kernel memory: 752K (c232b000 - c23e7000) [ 12.624537] Write protecting the kernel text: 13296k [ 12.626151] Write protecting the kernel read-only data: 5188k [ 12.773226] power_supply test_ac: uevent [ 12.774285] power_supply test_ac: POWER_SUPPLY_NAME=test_ac [ 12.775584] power_supply test_ac: prop ONLINE=1 [ 12.779504] power_supply test_battery: uevent [ 12.992439] power_supply test_ac: uevent [ 13.001889] power_supply test_ac: POWER_SUPPLY_NAME=test_ac [ 13.005496] power_supply test_ac: prop ONLINE=1 [ 13.006817] power_supply test_ac: uevent [ 13.007779] power_supply test_ac: POWER_SUPPLY_NAME=test_ac [ 13.009023] power_supply test_ac: prop ONLINE=1 [ 13.060458] power_supply test_battery: POWER_SUPPLY_NAME=test_battery [ 13.061843] power_supply test_battery: prop STATUS=Discharging [ 13.098699] power_supply test_battery: prop CHARGE_TYPE=Fast [ 13.102617] power_supply test_battery: prop HEALTH=Good [ 13.107691] VFS: could not find a valid V7 on nullb1. [ 13.109527] power_supply test_battery: prop PRESENT=1 [ 13.110696] power_supply test_battery: prop TECHNOLOGY=Li-ion [ 13.111991] power_supply test_battery: prop CHARGE_FULL_DESIGN=100 [ 13.132972] blk_update_request: I/O error, dev fd0, sector 0 [ 13.134261] floppy: error -5 while reading block 0 [ 13.136195] UDF-fs: warning (device nullb1): udf_fill_super: No partition found (2) [ 13.138224] Mount JFS Failure: -22 [ 13.139195] befs: (nullb1): ---> befs_fill_super [ 13.145252] power_supply test_battery: prop CHARGE_FULL=100 [ 13.147566] power_supply test_battery: prop CHARGE_NOW=50 [ 13.148807] power_supply test_battery: prop CAPACITY=50 [ 13.151282] VFS: could not find a valid V7 on nullb0. [ 13.152800] blk_update_request: I/O error, dev fd0, sector 0 [ 13.154055] floppy: error -5 while reading block 0 [ 13.156211] befs: (nullb1): No write support. Marking filesystem read-only [ 13.157672] befs: (nullb1): Using x86 superblock location [ 13.158891] befs: (nullb1): invalid magic header [ 13.160628] UDF-fs: warning (device nullb0): udf_fill_super: No partition found (2) [ 13.162562] Mount JFS Failure: -22 [ 13.163492] power_supply test_battery: prop CAPACITY_LEVEL=Normal [ 13.164826] power_supply test_battery: prop TIME_TO_EMPTY_AVG=3600 [ 13.168161] befs: (nullb0): ---> befs_fill_super [ 13.169263] befs: (nullb0): No write support. Marking filesystem read-only [ 13.170872] F2FS-fs (nullb1): Magic Mismatch, valid(0xf2f52010) - read(0x555507f7) [ 13.172681] F2FS-fs (nullb1): Can't find valid F2FS filesystem in 1th superblock [ 13.174493] blk_update_request: I/O error, dev fd0, sector 0 [ 13.175741] floppy: error -5 while reading block 0 [ 13.177178] power_supply test_battery: prop TIME_TO_FULL_NOW=3600 [ 13.178541] power_supply test_battery: prop MODEL_NAME=Test battery [ 13.181684] befs: (nullb0): Using x86 superblock location [ 13.182933] power_supply test_battery: prop MANUFACTURER=Linux [ 13.184219] power_supply test_battery: prop SERIAL_NUMBER=4.4.0-rc4-00093-ga80c47d [ 13.186005] power_supply test_battery: prop TEMP=26 [ 13.188144] befs: (nullb0): invalid magic header [ 13.189285] F2FS-fs (nullb0): Magic Mismatch, valid(0xf2f52010) - read(0x0) [ 13.190819] F2FS-fs (nullb1): Magic Mismatch, valid(0xf2f52010) - read(0x0) [ 13.192306] F2FS-fs (nullb1): Can't find valid F2FS filesystem in 2th superblock [ 13.195074] F2FS-fs (nullb0): Can't find valid F2FS filesystem in 1th superblock [ 13.196900] blk_update_request: I/O error, dev fd0, sector 0 [ 13.198190] floppy: error -5 while reading block 0 [ 13.200371] F2FS-fs (nullb1): Magic Mismatch, valid(0xf2f52010) - read(0x555507f7) [ 13.202173] F2FS-fs (nullb1): Can't find valid F2FS filesystem in 1th superblock [ 13.203960] power_supply test_battery: prop VOLTAGE_NOW=3300 [ 13.207039] power_supply test_battery: uevent [ 13.208114] power_supply test_battery: POWER_SUPPLY_NAME=test_battery [ 13.209556] F2FS-fs (nullb0): Magic Mismatch, valid(0xf2f52010) - read(0x9) [ 13.211029] F2FS-fs (nullb0): Can't find valid F2FS filesystem in 2th superblock [ 13.212873] power_supply test_usb: uevent [ 13.213861] power_supply test_usb: POWER_SUPPLY_NAME=test_usb [ 13.215144] power_supply test_usb: prop ONLINE=1 [ 13.217515] power_supply test_battery: prop STATUS=Discharging [ 13.218807] power_supply test_battery: prop CHARGE_TYPE=Fast [ 13.220095] blk_update_request: I/O error, dev fd0, sector 0 [ 13.221346] floppy: error -5 while reading block 0 [ 13.222782] F2FS-fs (nullb1): Magic Mismatch, valid(0xf2f52010) - read(0x0) [ 13.224266] F2FS-fs (nullb1): Can't find valid F2FS filesystem in 2th superblock [ 13.226687] power_supply test_battery: prop HEALTH=Good [ 13.227924] power_supply test_battery: prop PRESENT=1 [ 13.229229] power_supply test_battery: prop TECHNOLOGY=Li-ion [ 13.230547] F2FS-fs (nullb0): Magic Mismatch, valid(0xf2f52010) - read(0x0) [ 13.232039] F2FS-fs (nullb0): Can't find valid F2FS filesystem in 1th superblock [ 13.242809] blk_update_request: I/O error, dev fd0, sector 0 [ 13.244062] floppy: error -5 while reading block 0 [ 13.245636] power_supply test_usb: uevent [ 13.263093] blk_update_request: I/O error, dev fd0, sector 0 [ 13.264382] floppy: error -5 while reading block 0 [ 13.271971] power_supply test_usb: POWER_SUPPLY_NAME=test_usb [ 13.297889] power_supply test_battery: prop CHARGE_FULL_DESIGN=100 [ 13.337432] blk_update_request: I/O error, dev fd0, sector 0 [ 13.338722] floppy: error -5 while reading block 0 [ 13.347037] F2FS-fs (nullb0): Magic Mismatch, valid(0xf2f52010) - read(0x9) [ 13.348529] F2FS-fs (nullb0): Can't find valid F2FS filesystem in 2th superblock [ 13.360630] blk_update_request: I/O error, dev fd0, sector 0 [ 13.361898] floppy: error -5 while reading block 0 [ 13.416467] blk_update_request: I/O error, dev fd0, sector 0 [ 13.417755] floppy: error -5 while reading block 0 [ 13.467319] power_supply test_usb: prop ONLINE=1 [ 13.472666] power_supply test_battery: prop CHARGE_FULL=100 [ 13.490142] floppy: error -5 while reading block 0 [ 13.492079] power_supply test_battery: prop CHARGE_NOW=50 [ 13.493350] power_supply test_battery: prop CAPACITY=50 [ 13.494555] power_supply test_battery: prop CAPACITY_LEVEL=Normal [ 13.495902] power_supply test_battery: prop TIME_TO_EMPTY_AVG=3600 [ 13.519334] floppy: error -5 while reading block 0 [ 13.521736] power_supply test_battery: prop TIME_TO_FULL_NOW=3600 [ 13.523549] power_supply test_battery: prop MODEL_NAME=Test battery [ 13.524917] power_supply test_battery: prop MANUFACTURER=Linux [ 13.539749] floppy: error -5 while reading block 0 [ 13.542894] power_supply test_battery: prop SERIAL_NUMBER=4.4.0-rc4-00093-ga80c47d [ 13.544793] power_supply test_battery: prop TEMP=26 [ 13.545943] power_supply test_battery: prop VOLTAGE_NOW=3300 [ 13.572913] floppy: error -5 while reading block 0 [ 13.597396] floppy: error -5 while reading block 0 [ 13.616150] floppy: error -5 while reading block 0 [ 13.636152] floppy: error -5 while reading block 0 [ 13.656146] floppy: error -5 while reading block 0 [ 13.676160] floppy: error -5 while reading block 0 [ 13.696152] floppy: error -5 while reading block 0 [ 13.716152] floppy: error -5 while reading block 0 [ 13.736152] floppy: error -5 while reading block 0 [ 13.758396] floppy: error -5 while reading block 0 [ 13.784390] floppy: error -5 while reading block 0 [ 13.806150] floppy: error -5 while reading block 0 [ 13.850819] floppy: error -5 while reading block 0 [ 13.851977] ------------[ cut here ]------------ [ 13.853076] WARNING: CPU: 0 PID: 6 at kernel/locking/lockdep.c:3183 __lock_acquire+0x99e/0xd90() [ 13.855335] DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS) [ 13.856230] CPU: 0 PID: 6 Comm: kworker/u2:0 Not tainted 4.4.0-rc4-00093-ga80c47d #2 [ 13.871377] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 13.873304] Workqueue: floppy fd_timer_workfn [ 13.874385] 00000000 00000000 cece7cb0 c1487672 cece7cf0 cece7ce0 c1051f4e c2085bed [ 13.876896] cece7d0c 00000006 c208f2d4 00000c6f c1095e7e c1095e7e cece852c 00000003 [ 13.879403] cece8000 cece7cf8 c1051fce 00000009 cece7cf0 c2085bed cece7d0c cece7d30 [ 13.886926] Call Trace: [ 13.887623] [] dump_stack+0x4b/0x79 [ 13.888636] [] warn_slowpath_common+0x7e/0xb0 [ 13.889768] [] ? __lock_acquire+0x99e/0xd90 [ 13.890965] [] ? __lock_acquire+0x99e/0xd90 [ 13.892106] [] warn_slowpath_fmt+0x2e/0x30 [ 13.893105] [] __lock_acquire+0x99e/0xd90 [ 13.894281] [] lock_acquire+0x77/0xa0 [ 13.895313] [] ? complete+0x1b/0x50 [ 13.896319] [] _raw_spin_lock_irqsave+0x4f/0x70 [ 13.897484] [] ? complete+0x1b/0x50 [ 13.898459] [] complete+0x1b/0x50 [ 13.912483] [] floppy_rb0_cb+0x1e/0x50 [ 13.913609] [] bio_endio+0x38/0x70 [ 13.914647] [] blk_update_request+0x85/0x2c0 [ 13.915822] [] blk_update_bidi_request+0x18/0x90 [ 13.917091] [] __blk_end_bidi_request+0x20/0x40 [ 13.918352] [] __blk_end_request+0x12/0x20 [ 13.919551] [] floppy_end_request+0x5b/0x90 [ 13.920757] [] request_done+0xb7/0x180 [ 13.921860] [] ? disk_change+0xd8/0x340 [ 13.940617] [] floppy_ready+0x5c3/0x6b0 [ 13.941774] [] ? process_one_work+0xfa/0x400 [ 13.942984] [] fd_timer_workfn+0x9/0x10 [ 13.944132] [] process_one_work+0x175/0x400 [ 13.945314] [] ? process_one_work+0xfa/0x400 [ 13.946522] [] worker_thread+0x39/0x430 [ 13.947671] [] ? process_one_work+0x400/0x400 [ 13.948897] [] kthread+0xac/0xc0 [ 13.949925] [] ? finish_task_switch+0xbb/0x290 [ 13.951167] [] ret_from_kernel_thread+0x21/0x38 [ 13.952412] [] ? __kthread_unpark+0x70/0x70 [ 13.953601] ---[ end trace 1e31e1e3e1c50347 ]--- [ 13.954713] BUG: unable to handle kernel NULL pointer dereference at (null) [ 13.956462] IP: [< (null)>] (null) [ 13.957508] *pde = 00000000 [ 13.958424] Oops: 0010 [#1] PREEMPT SMP [ 13.959713] CPU: 0 PID: 6 Comm: kworker/u2:0 Tainted: G W 4.4.0-rc4-00093-ga80c47d #2 [ 13.961774] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 13.963837] Workqueue: floppy fd_timer_workfn [ 13.965004] task: cece8000 ti: cece6000 task.ti: cece6000 [ 13.966241] EIP: 0060:[<00000000>] EFLAGS: 00010002 CPU: 0 [ 13.967487] EIP is at 0x0 [ 13.968257] EAX: cd6a9674 EBX: cd6a9674 ECX: 00000000 EDX: 00000003 [ 13.969646] ESI: fffffff4 EDI: 00000000 EBP: cece7d70 ESP: cece7d4c [ 13.971012] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 13.972258] CR0: 80050033 CR2: 00000000 CR3: 0d752000 CR4: 00140690 [ 13.973650] Stack: [ 13.974319] c108a415 00000000 00000001 cd6dbd48 00000003 00000000 cd6dbd28 cd6dbd24 [ 13.976968] 00000092 cece7d80 c108a6ea 00000000 00000000 cece7d94 c108ac30 cd6dbd20 [ 13.979653] 00000000 00001000 cece7dac c17cd38e c217ba9c fffffffb cd6dbcd0 00001000 [ 13.982339] Call Trace: [ 13.983074] [] ? __wake_up_common+0x45/0x70 [ 13.984183] [] __wake_up_locked+0x1a/0x20 [ 13.985325] [] complete+0x30/0x50 [ 13.986368] [] floppy_rb0_cb+0x1e/0x50 [ 13.987490] [] bio_endio+0x38/0x70 [ 13.988539] [] blk_update_request+0x85/0x2c0 [ 13.989763] [] blk_update_bidi_request+0x18/0x90 [ 13.991043] [] __blk_end_bidi_request+0x20/0x40 [ 13.992311] [] __blk_end_request+0x12/0x20 [ 13.993497] [] floppy_end_request+0x5b/0x90 [ 13.994701] [] request_done+0xb7/0x180 [ 13.995830] [] ? disk_change+0xd8/0x340 [ 13.996963] [] floppy_ready+0x5c3/0x6b0 [ 13.998103] [] ? process_one_work+0xfa/0x400 [ 13.999312] [] fd_timer_workfn+0x9/0x10 [ 14.000477] [] process_one_work+0x175/0x400 [ 14.001643] [] ? process_one_work+0xfa/0x400 [ 14.002815] [] worker_thread+0x39/0x430 [ 14.004015] [] ? process_one_work+0x400/0x400 [ 14.005207] [] kthread+0xac/0xc0 [ 14.006222] [] ? finish_task_switch+0xbb/0x290 [ 14.007442] [] ret_from_kernel_thread+0x21/0x38 [ 14.008679] [] ? __kthread_unpark+0x70/0x70 [ 14.009956] Code: Bad EIP value. [ 14.011033] EIP: [<00000000>] 0x0 SS:ESP 0068:cece7d4c [ 14.012440] CR2: 0000000000000000 [ 14.013384] ---[ end trace 1e31e1e3e1c50348 ]--- [ 14.014494] Kernel panic - not syncing: Fatal exception [ 14.015702] Kernel Offset: disabled > > # extra tests on tree/branch linux-next/master > > git bisect bad 8225f4e85cb03daea14661380745886ce01fd83a # 03:42 0- 3 Add linux-next specific files for 20151210 > > Hm, unfortunately I can't checkout this commit (it comes from linux-next > and it's been rebased/regenerated since then). Sorry, that's one more independent NULL pointer bug. There are so many noises! [ 9.918393] floppy: error -5 while reading block 0 [ 9.938396] floppy: error -5 while reading block 0 Kernel tests: Boot OK! [ 10.649260] random: trinity urandom read with 53 bits of entropy available [ 20.702989] sock: process `trinity-main' is using obsolete setsockopt SO_BSDCOMPAT [ 20.825027] BUG: unable to handle kernel NULL pointer dereference at 0000019c [ 20.825033] IP: [] perf_prepare_sample+0x271/0x3a0 [ 20.825034] *pde = 00000000 [ 20.825036] Oops: 0000 [#1] PREEMPT SMP [ 20.825039] CPU: 0 PID: 686 Comm: trinity-main Not tainted 4.4.0-rc4-next-20151210 #1 [ 20.825040] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 20.825041] task: cd6bad00 ti: cd49e000 task.ti: cd49e000 [ 20.825042] EIP: 0060:[] EFLAGS: 00010006 CPU: 0 [ 20.825043] EIP is at perf_prepare_sample+0x271/0x3a0 [ 20.825044] EAX: 0000019c EBX: cd49fd54 ECX: cd49fe40 EDX: 0d64b000 [ 20.825045] ESI: 0002e3e9 EDI: cd71d800 EBP: cd49fd3c ESP: cd49fd24 [ 20.825046] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 20.825046] CR0: 80050033 CR2: 0000019c CR3: 0db9e000 CR4: 00140690 [ 20.825049] Stack: [ 20.825052] 00000000 00000000 cd49fe40 cd71d800 cd49fe40 cfa4da40 cd49fd80 c10df073 [ 20.825059] cfa4da40 00000000 00000000 c10df020 00000009 00500001 cd6bad00 01000002 [ 20.825062] 00000002 00000000 00000000 cd71d800 00000000 cd71d800 00000000 cd49fda8 [ 20.825062] Call Trace: [ 20.825065] [] perf_event_output+0x53/0xb0 [ 20.825066] [] ? perf_prepare_sample+0x3a0/0x3a0 [ 20.825068] [] __perf_event_overflow+0x235/0x260 [ 20.825070] [] perf_swevent_overflow+0x4f/0x90 [ 20.825071] [] perf_swevent_event+0xcd/0x100 [ 20.825073] [] ___perf_sw_event+0x1c4/0x220 [ 20.825075] [] ? ___perf_sw_event+0x22/0x220 [ 20.825077] [] ? __lock_is_held+0x46/0x60 [ 20.825080] [] ? schedule+0x32/0x90 [ 20.825082] [] ? __lock_acquire+0x4c0/0xd90 [ 20.825083] [] ? __lock_is_held+0x46/0x60 [ 20.825084] [] ? __lock_is_held+0x46/0x60 [ 20.825085] [] __schedule+0x511/0x9d0 [ 20.825086] [] schedule+0x32/0x90 [ 20.825088] [] exit_to_usermode_loop+0x70/0xa0 [ 20.825090] [] prepare_exit_to_usermode+0x27/0x30 [ 20.825092] [] resume_userspace+0xe/0x14 [ 20.825093] [] ? ldsem_down_read+0x10/0x90 [ 20.825111] Code: 00 00 00 c7 41 3c 00 00 00 00 89 41 38 0f 84 0c fe ff ff 8b 55 08 89 f8 e8 6d 3e 00 00 8b 4d f0 85 c0 89 41 68 0f 84 ff 00 00 00 <8b> 00 8d 04 c5 08 00 00 00 0f b7 c0 66 01 43 06 e9 df fd ff ff [ 20.825113] EIP: [] perf_prepare_sample+0x271/0x3a0 SS:ESP 0068:cd49fd24 [ 20.825114] CR2: 000000000000019c [ 20.825116] ---[ end trace ea295fc74974f372 ]--- [ 20.825117] Kernel panic - not syncing: Fatal exception Thanks, Fengguang