list_add corruption. next->prev should be prev (ffff88021fffab68), but was ffffea000a75f9a0. (next=ffffea00099ac220).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:25!
invalid opcode: 0000 [#1] SMP PTI
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 6571 Comm: udevd Not tainted 4.17.0+ #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__list_add_valid+0x275/0x450 lib/list_debug.c:23
RSP: 0018:ffff88013da8f2a0 EFLAGS: 00010086
RAX: 0000000000000075 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88021fd36eec
RBP: ffff88013da8f308 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffffffff86575950 R12: ffffea00099ac220
R13: ffffea000a75f9a0 R14: 0000000000000000 R15: ffffffff8b58d000
FS:  00007f1da0e2b7a0(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000003f6 CR3: 0000000125a9a000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __list_add include/linux/list.h:60 [inline]
 list_add include/linux/list.h:79 [inline]
 __free_one_page+0x1483/0x1800 mm/page_alloc.c:876
 free_one_page mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0x870/0x1680 mm/page_alloc.c:1260
 __free_pages+0x109/0x240 mm/page_alloc.c:4442
 kmsan_free_page+0x197/0x2e0 mm/kmsan/kmsan.c:959
 free_pages_prepare mm/page_alloc.c:996 [inline]
 __free_pages_ok+0x288/0x1680 mm/page_alloc.c:1254
 __free_pages mm/page_alloc.c:4442 [inline]
 free_pages+0x1e7/0x320 mm/page_alloc.c:4452
 _pgd_free arch/x86/mm/pgtable.c:367 [inline]
 pgd_free+0x2b2/0x360 arch/x86/mm/pgtable.c:416
 mm_free_pgd kernel/fork.c:551 [inline]
 __mmdrop+0x139/0x930 kernel/fork.c:599
 mmdrop include/linux/sched/mm.h:49 [inline]
 __mmput+0x550/0x600 kernel/fork.c:972
 mmput+0xab/0xf0 kernel/fork.c:983
 exit_mm+0x6ed/0x7a0 kernel/exit.c:545
 do_exit+0xc12/0x3930 kernel/exit.c:854
 do_group_exit+0x1a0/0x360 kernel/exit.c:970
 get_signal+0x1405/0x1ec0 kernel/signal.c:2482
 do_signal+0xb8/0x1d20 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:162 [inline]
 prepare_exit_to_usermode+0x271/0x3a0 arch/x86/entry/common.c:196
 retint_user+0x8/0x8
RIP: 0033:0x41a920
RSP: 002b:00007ffc3de56a88 EFLAGS: 00010246
RAX: 00000000000003f6 RBX: 00000000008589e8 RCX: 0000000000000400
RDX: 00007ffc3de56f90 RSI: 00007ffc3de56f90 RDI: 0000000000844250
RBP: 0000000000844360 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f1da05774c0 R11: 2a5d392d305b6466 R12: 0000000000849e10
R13: 0000000000625500 R14: 0000000000844250 R15: 0000000000849e10
Code: 87 80 0c 00 00 00 00 00 00 41 c7 87 20 03 00 00 00 00 00 00 48 c7 c7 e4 b0 9c 8a 31 c0 48 89 d6 4c 89 ea 4c 89 e1 e8 1b a5 3e fd <0f> 0b 66 0f 1f 84 00 00 00 00 00 eb fe 48 8b 7d c8 e8 b5 9d be 
RIP: __list_add_valid+0x275/0x450 lib/list_debug.c:23 RSP: ffff88013da8f2a0
---[ end trace 7bf34839d2e4b348 ]---