BUG: kernel NULL pointer dereference, address: 000000000000009c
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD a43eb067 P4D a43eb067 PUD a5d6c067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 0 PID: 6351 Comm: syz-executor.0 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kcsan_setup_watchpoint+0x215/0x4d0 kernel/kcsan/core.c:479
Code: 9d 4c 89 74 24 50 eb 05 ff 74 24 50 9d 48 83 c4 60 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f b7 08 89 ca c1 ea 08 31 db 31 f6 eb 26 <8b> 08 89 ca c1 ea 08 89 ce c1 ee 10 eb 18 48 8b 08 48 89 ca 48 c1
RSP: 0018:ffffc90001e5fd00 EFLAGS: 00010046
RAX: 000000000000009c RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 00000000aaaaaaab R09: 000800000000009c
R10: 0000000000000246 R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000000 R14: 00fff00000000200 R15: 0000000000000001
FS:  00007fa0371f8700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000009c CR3: 00000000a5d4b000 CR4: 00000000001526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 afs_unuse_cell+0x24/0x2b0 fs/afs/cell.c:592
 afs_destroy_sbi+0x93/0x120 fs/afs/super.c:525
 afs_kill_super+0xb8/0xc0 fs/afs/super.c:546
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
 task_work_run+0x8e/0x110 kernel/task_work.c:151
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
 exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4608aa
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 ad 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 8a 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007fa0371f7a88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffea RBX: 00007fa0371f7b20 RCX: 00000000004608aa
RDX: 0000000020000000 RSI: 0000000020000040 RDI: 0000000000000000
RBP: 00007fa0371f7ae0 R08: 00007fa0371f7b20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000040 R14: 0000000000000000 R15: 00000000200000c0
Modules linked in:
CR2: 000000000000009c
---[ end trace 9373afbed44d795c ]---
RIP: 0010:kcsan_setup_watchpoint+0x215/0x4d0 kernel/kcsan/core.c:479
Code: 9d 4c 89 74 24 50 eb 05 ff 74 24 50 9d 48 83 c4 60 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f b7 08 89 ca c1 ea 08 31 db 31 f6 eb 26 <8b> 08 89 ca c1 ea 08 89 ce c1 ee 10 eb 18 48 8b 08 48 89 ca 48 c1
RSP: 0018:ffffc90001e5fd00 EFLAGS: 00010046
RAX: 000000000000009c RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 00000000aaaaaaab R09: 000800000000009c
R10: 0000000000000246 R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000000 R14: 00fff00000000200 R15: 0000000000000001
FS:  00007fa0371f8700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000009c CR3: 00000000a5d4b000 CR4: 00000000001526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400