FYI, we noticed the following commit (built with gcc-7):

commit: 7589238a8cf37331607c3222a64ac3140b29532d ("Revert "software node: Simplify software_node_release() function"")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

in testcase: boot

on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G

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


+-----------------------------------------------------------------------------+----------+------------+
|                                                                             | v5.6-rc4 | 7589238a8c |
+-----------------------------------------------------------------------------+----------+------------+
| boot_successes                                                              | 13       | 0          |
| boot_failures                                                               | 2        | 4          |
| BUG:kernel_hang_in_early-boot_stage,last_printk:early_console_in_setup_code | 1        |            |
| BUG:kernel_hang_in_boot_stage                                               | 1        |            |
| BUG:kernel_NULL_pointer_dereference,address                                 | 0        | 4          |
| Oops:#[##]                                                                  | 0        | 4          |
| EIP:ida_free                                                                | 0        | 4          |
| Kernel_panic-not_syncing:Fatal_exception                                    | 0        | 4          |
+-----------------------------------------------------------------------------+----------+------------+


If you fix the issue, kindly add following tag
Reported-by: kernel test robot <rong.a.chen@intel.com>


[   24.515111] BUG: kernel NULL pointer dereference, address: 00000000
[   24.515352] #PF: supervisor read access in kernel mode
[   24.515352] #PF: error_code(0x0000) - not-present page
[   24.515352] *pdpt = 0000000000000000 *pde = f000ff53f000ff53 
[   24.515352] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[   24.515352] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc4-00001-g7589238a8cf37 #1
[   24.515352] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[   24.515352] EIP: ida_free+0x90/0x100
[   24.515352] Code: ee 0f a3 fe 73 6c ba fe ff ff ff 89 f9 d3 c2 21 d6 74 43 8d 54 36 01 8d 45 dc e8 8b 1a 01 00 eb 3f 8d b4 26 00 00 00 00 66 90 <0f> a3 38 73 43 0f b3 38 8d 45 dc 31 d2 e8 0e 06 01 00 ba 00 04 00
[   24.515352] EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000000
[   24.515352] ESI: 00000000 EDI: 00000000 EBP: c0045e48 ESP: c0045e20
[   24.515352] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010046
[   24.515352] CR0: 80050033 CR2: 00000000 CR3: 01d60000 CR4: 000406b0
[   24.515352] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[   24.515352] DR6: fffe0ff0 DR7: 00000400
[   24.515352] Call Trace:
[   24.515352]  software_node_release+0x1c/0x80
[   24.515352]  kobject_put+0x15b/0x1a0
[   24.515352]  kobject_del+0x40/0x50
[   24.515352]  kobject_put+0x12c/0x1a0
[   24.515352]  fwnode_remove_software_node+0x25/0x40
[   24.515352]  software_node_unregister_nodes+0x23/0x30
[   24.515352]  test_pointer+0xaf0/0xb0e
[   24.515352]  ? test_pointer+0xb0e/0xb0e
[   24.515352]  test_printf_init+0x369/0x3cf
[   24.515352]  do_one_initcall+0xbe/0x240
[   24.515352]  ? parse_args+0x120/0x390
[   24.515352]  ? kernel_init_freeable+0x168/0x22f
[   24.515352]  kernel_init_freeable+0x183/0x22f
[   24.515352]  ? rest_init+0x110/0x110
[   24.515352]  kernel_init+0x8/0x100
[   24.515352]  ret_from_fork+0x1e/0x28
[   24.515352] Modules linked in:
[   24.515352] CR2: 0000000000000000
[   24.515352] ---[ end trace c67c8ea5ea485b03 ]---


To reproduce:

        # build kernel
	cd linux
	cp config-5.6.0-rc4-00001-g7589238a8cf37 .config
	make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 olddefconfig prepare modules_prepare bzImage

        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,
Rong Chen