list_add corruption. next->prev should be prev (ffff88021fffab78), but was ffff88021fffab70. (next=ffffea000ab19ca0).
------------[ 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: 4776 Comm: syz-executor Not tainted 4.17.0+ #8
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: 0000:ffff88016561f620 EFLAGS: 00010082
RAX: 0000000000000075 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88021fd36eec
RBP: ffff88016561f688 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffffffff865758f0 R12: ffffea000ab19ca0
R13: ffff88021fffab70 R14: 0000000000000000 R15: ffffffff8b58d000
FS:  00000000015c5940(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f19df06b1ad CR3: 00000001656b8000 CR4: 00000000001406e0
DR0: 0000000020abe000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
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:956
 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+0xc2/0xd0 include/linux/sched/mm.h:49
 finish_task_switch+0x103/0x270 kernel/sched/core.c:2743
 context_switch kernel/sched/core.c:2883 [inline]
 __schedule+0x66b/0x770 kernel/sched/core.c:3524
 schedule+0x1cc/0x2f0 kernel/sched/core.c:3568
 freezable_schedule include/linux/freezer.h:172 [inline]
 do_nanosleep+0x2c3/0x9c0 kernel/time/hrtimer.c:1689
 hrtimer_nanosleep kernel/time/hrtimer.c:1743 [inline]
 __do_sys_nanosleep kernel/time/hrtimer.c:1775 [inline]
 __se_sys_nanosleep+0x4b3/0x6a0 kernel/time/hrtimer.c:1762
 __x64_sys_nanosleep+0x92/0xc0 kernel/time/hrtimer.c:1762
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x481230
RSP: 002b:0000000000a3ea98 EFLAGS: 00000246 ORIG_RAX: 0000000000000023
RAX: ffffffffffffffda RBX: 000000000000017b RCX: 0000000000481230
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000a3eaa0
RBP: 000000000004674d R08: 0000000000000001 R09: 00000000015c5940
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000a R14: 000000000000045c R15: 000000000004639f
Code: 87 80 0c 00 00 00 00 00 00 41 c7 87 20 03 00 00 00 00 00 00 48 c7 c7 64 b0 9c 8a 31 c0 48 89 d6 4c 89 ea 4c 89 e1 e8 7b 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: ffff88016561f620
---[ end trace aa1e4b7968bc3e73 ]---