BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 1084bc067 P4D 1084bc067 PUD 10a367067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 0 PID: 26446 Comm: syz-executor.5 Not tainted 5.9.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:arch_atomic64_read arch/x86/include/asm/atomic64_64.h:22 [inline]
RIP: 0010:atomic64_read include/asm-generic/atomic-instrumented.h:838 [inline]
RIP: 0010:atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
RIP: 0010:percpu_ref_exit+0x28/0x50 lib/percpu-refcount.c:136
Code: 66 90 55 53 48 89 fb 48 8b 6f 08 e8 c2 ff ff ff 48 c7 c7 80 1c 43 84 e8 66 68 38 01 48 8b 53 08 48 c7 c7 80 1c 43 84 48 89 c6 <48> 8b 12 48 c7 43 08 00 00 00 00 48 c1 e2 02 48 09 13 e8 61 64 38
RSP: 0018:ffffc9000c6cbbc0 EFLAGS: 00010046
RAX: 0000000000000286 RBX: ffff888108ffe820 RCX: 00000000adcb976d
RDX: 0000000000000000 RSI: 0000000000000286 RDI: ffffffff84431c80
RBP: 0000000000000000 R08: 0000000000000028 R09: 0000000000000001
R10: ffff88810b118200 R11: 5b0c99f47ebe1170 R12: ffffffff8445ec40
R13: ffff88810ec95f60 R14: 0000000000000000 R15: ffff8881290e4800
FS:  00007fc44365f700(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010b364000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 hd_free_part block/partitions/../blk.h:391 [inline]
 part_release+0x31/0x40 block/partitions/core.c:262
 device_release+0x1f/0x70 drivers/base/core.c:1800
 kobject_cleanup lib/kobject.c:704 [inline]
 kobject_release lib/kobject.c:735 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x5f/0xc0 lib/kobject.c:752
 add_partition+0x411/0x4a0 block/partitions/core.c:493
 blk_add_partition block/partitions/core.c:685 [inline]
 blk_add_partitions+0x302/0x400 block/partitions/core.c:761
 bdev_disk_changed+0x78/0xf0 fs/block_dev.c:1417
 loop_reread_partitions+0x22/0x40 drivers/block/loop.c:658
 loop_set_status+0x1c1/0x380 drivers/block/loop.c:1427
 loop_set_status64 drivers/block/loop.c:1547 [inline]
 lo_ioctl+0x154/0x6a0 drivers/block/loop.c:1715
 __blkdev_driver_ioctl block/ioctl.c:224 [inline]
 blkdev_ioctl+0x1c6/0x2b0 block/ioctl.c:620
 block_ioctl+0x3a/0x40 fs/block_dev.c:1870
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x7c/0xb0 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d427
Code: 48 83 c4 08 48 89 d8 5b 5d c3 66 0f 1f 84 00 00 00 00 00 48 89 e8 48 f7 d8 48 39 c3 0f 92 c0 eb 92 66 90 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 bd b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc44365e9f8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000020000040 RCX: 000000000045d427
RDX: 00007fc44365eac0 RSI: 0000000000004c04 RDI: 0000000000000004
RBP: 000000000118cf80 R08: 0000000020015898 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000118cf4c
R13: 00007ffe536ffe8f R14: 00007fc44365f9c0 R15: 000000000118cf4c
Modules linked in:
CR2: 0000000000000000
---[ end trace b6653f19250fd59b ]---
RIP: 0010:arch_atomic64_read arch/x86/include/asm/atomic64_64.h:22 [inline]
RIP: 0010:atomic64_read include/asm-generic/atomic-instrumented.h:838 [inline]
RIP: 0010:atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
RIP: 0010:percpu_ref_exit+0x28/0x50 lib/percpu-refcount.c:136
Code: 66 90 55 53 48 89 fb 48 8b 6f 08 e8 c2 ff ff ff 48 c7 c7 80 1c 43 84 e8 66 68 38 01 48 8b 53 08 48 c7 c7 80 1c 43 84 48 89 c6 <48> 8b 12 48 c7 43 08 00 00 00 00 48 c1 e2 02 48 09 13 e8 61 64 38
RSP: 0018:ffffc9000c6cbbc0 EFLAGS: 00010046
RAX: 0000000000000286 RBX: ffff888108ffe820 RCX: 00000000adcb976d
RDX: 0000000000000000 RSI: 0000000000000286 RDI: ffffffff84431c80
RBP: 0000000000000000 R08: 0000000000000028 R09: 0000000000000001
R10: ffff88810b118200 R11: 5b0c99f47ebe1170 R12: ffffffff8445ec40
R13: ffff88810ec95f60 R14: 0000000000000000 R15: ffff8881290e4800
FS:  00007fc44365f700(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010b364000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400