FYI, we noticed the following commit (built with gcc-4.8):

commit: 81d387190039c14edac8de2b3ec789beb899afd9 ("x86/kconfig: Consolidate unwinders into multiple choice selection")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

in testcase: boot

on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -m 512M

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+------------------------------------------+------------+------------+
|                                          | a34a766ff9 | 81d3871900 |
+------------------------------------------+------------+------------+
| boot_successes                           | 24         | 5          |
| boot_failures                            | 12         | 31         |
| BUG:kernel_hang_in_test_stage            | 12         | 1          |
| BUG:unable_to_handle_kernel              | 0          | 30         |
| Oops:#[##]                               | 0          | 30         |
| Kernel_panic-not_syncing:Fatal_exception | 0          | 30         |
+------------------------------------------+------------+------------+



[    5.324797] BUG: unable to handle kernel paging request at ffff88001c4b0000
[    5.326126] IP: slob_free+0x2bf/0x3d7
[    5.328023] PGD 17d9c067 
[    5.328023] P4D 17d9c067 
[    5.328023] PUD 17d9d067 
[    5.328023] PMD 1f91e067 
[    5.328023] PTE 800000001c4b0060
[    5.328023] 
[    5.328023] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[    5.328023] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc1-00044-g81d3871 #1
[    5.328023] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    5.328023] task: ffff8800002fa000 task.stack: ffffc900000d0000
[    5.328023] RIP: 0010:slob_free+0x2bf/0x3d7
[    5.328023] RSP: 0000:ffffc900000d3d58 EFLAGS: 00010002
[    5.328023] RAX: 0000000000000027 RBX: ffff88001c4affb0 RCX: 0000000000000000
[    5.328023] RDX: ffff88001c4af000 RSI: 0000000000000000 RDI: ffff88001c4afffe
[    5.328023] RBP: ffff88001c4afffe R08: 0000000000000001 R09: 0000000000000000
[    5.328023] R10: ffffea000069a420 R11: ffff88001ffdb000 R12: ffff88001c4aff5c
[    5.328023] R13: 0000000000000027 R14: 0000000000000027 R15: 0000000000000027
[    5.328023] FS:  0000000000000000(0000) GS:ffff88001f600000(0000) knlGS:0000000000000000
[    5.328023] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    5.328023] CR2: ffff88001c4b0000 CR3: 0000000016211000 CR4: 00000000000406b0
[    5.328023] Call Trace:
[    5.328023]  ? link_target+0xb2/0xc7
[    5.328023]  kfree+0x158/0x1b6
[    5.328023]  link_target+0xb2/0xc7
[    5.328023]  new_node+0x32b/0x4d1
[    5.328023]  gcov_event+0x33e/0x546
[    5.328023]  ? gcov_persist_setup+0xbb/0xbb
[    5.328023]  gcov_enable_events+0x3c/0x89
[    5.328023]  gcov_fs_init+0x134/0x191
[    5.328023]  do_one_initcall+0x10e/0x2df
[    5.328023]  kernel_init_freeable+0x3ec/0x559
[    5.328023]  ? rest_init+0x145/0x145
[    5.328023]  kernel_init+0xc/0x1a8
[    5.328023]  ret_from_fork+0x2a/0x40
[    5.328023] Code: e8 8d f7 ff ff 48 ff 05 c9 8c 91 02 85 c0 75 51 49 0f bf c5 48 ff 05 c2 8c 91 02 48 8d 3c 43 48 39 ef 75 3d 48 ff 05 ba 8c 91 02 <8b> 6d 00 66 85 ed 7e 09 48 ff 05 b3 8c 91 02 eb 05 bd 01 00 00 
[    5.328023] RIP: slob_free+0x2bf/0x3d7 RSP: ffffc900000d3d58
[    5.328023] CR2: ffff88001c4b0000
[    5.328023] ---[ end trace f8ee1579929b04f0 ]---


To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script  # job-script is attached in this email



Thanks,
Xiaolong