8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 000000a0
pgd = 86bfcec0
[000000a0] *pgd=845ca003, *pmd=fe59f003
Internal error: Oops: 207 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 1 PID: 6322 Comm: iou-sqp-6317 Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: ARM-Versatile Express
PC is at atomic_add arch/arm/include/asm/atomic.h:223 [inline]
PC is at atomic_inc include/linux/atomic-fallback.h:372 [inline]
PC is at io_uring_cancel_sqpoll+0xac/0x1a0 fs/io_uring.c:8926
LR is at io_sq_thread+0x3d0/0x6f8 fs/io_uring.c:6772
pc : [<80561f00>]    lr : [<80566f50>]    psr: 60000113
sp : 86c1dee0  ip : 835d5140  fp : 86c1df2c
r10: 00000000  r9 : 86c1c000  r8 : 00000000
r7 : 86af5000  r6 : 86a0f600  r5 : 86a0f654  r4 : 86af5000
r3 : 000000a0  r2 : 86c1c000  r1 : 000000a0  r0 : 86c1def4
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 30c5387d  Table: 86bfcec0  DAC: 00000000
Process iou-sqp-6317 (pid: 6322, stack limit = 0x86c1c210)
Stack: (0x86c1dee0 to 0x86c1e000)
dee0: 00000000 000000a0 00000000 835d5140 802a6878 86c1def4 86c1def4 56b92eae
df00: 00000001 86af5000 86a0f654 86a0f600 00000000 00000000 86c1c000 00000000
df20: 86c1dfac 86c1df30 80566f50 80561e60 86a0f604 81f744cc 82a06d00 00000000
df40: 80384db8 86a0f600 835a8b00 86a0f654 00000000 00000000 00000000 835d5140
df60: 802a6878 86c1df64 86c1df64 2d756f69 2d707173 37313336 80258400 56b92eae
df80: 00000000 86a0f600 80566b80 00000000 00000000 00000000 00000000 00000000
dfa0: 00000000 86c1dfb0 80200114 80566b8c 00000000 00000000 00000000 00000000
dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
dfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
Backtrace: 
[<80561e54>] (io_uring_cancel_sqpoll) from [<80566f50>] (io_sq_thread+0x3d0/0x6f8 fs/io_uring.c:6772)
 r10:00000000 r9:86c1c000 r8:00000000 r7:00000000 r6:86a0f600 r5:86a0f654
 r4:86af5000
[<80566b80>] (io_sq_thread) from [<80200114>] (ret_from_fork+0x14/0x20 arch/arm/kernel/entry-common.S:158)
Exception stack(0x86c1dfb0 to 0x86c1dff8)
dfa0:                                     00000000 00000000 00000000 00000000
dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
 r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80566b80
 r4:86a0f600
Code: e28830a0 e50b3048 f593f000 e1a01003 (e1913f9f) 
---[ end trace 6c0cef1609ddc14e ]---
----------------
Code disassembly (best guess):
   0:	e28830a0 	add	r3, r8, #160	; 0xa0
   4:	e50b3048 	str	r3, [fp, #-72]	; 0xffffffb8
   8:	f593f000 	pldw	[r3]
   c:	e1a01003 	mov	r1, r3
* 10:	e1913f9f 	ldrex	r3, [r1] <-- trapping instruction