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BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
BUG: KASAN: null-ptr-deref in atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
BUG: KASAN: null-ptr-deref in percpu_ref_exit+0x102/0x1f0 lib/percpu-refcount.c:136
Read of size 8 at addr 0000000000000000 by task syz-executor.4/24953

CPU: 0 PID: 24953 Comm: syz-executor.4 Not tainted 5.9.0-rc3-next-20200903-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x198/0x1fd lib/dump_stack.c:118
 __kasan_report mm/kasan/report.c:517 [inline]
 kasan_report.cold+0x5/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
 percpu_ref_exit+0x102/0x1f0 lib/percpu-refcount.c:136
 hd_free_part block/partitions/../blk.h:391 [inline]
 part_release+0x9d/0xc0 block/partitions/core.c:262
 device_release+0x9f/0x240 drivers/base/core.c:1802
 kobject_cleanup lib/kobject.c:708 [inline]
 kobject_release lib/kobject.c:739 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x171/0x270 lib/kobject.c:756
 put_device+0x1b/0x30 drivers/base/core.c:3031
 add_partition+0x648/0xb00 block/partitions/core.c:493
 bdev_add_partition+0xb6/0x130 block/partitions/core.c:529
 blkpg_do_ioctl+0x2be/0x330 block/ioctl.c:52
 blkpg_ioctl block/ioctl.c:69 [inline]
 blkdev_ioctl+0x58a/0x700 block/ioctl.c:589
 block_ioctl+0xf9/0x140 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+0x193/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d5b9
Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f366c73bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000008c40 RCX: 000000000045d5b9
RDX: 0000000020000000 RSI: 0000000000001269 RDI: 0000000000000004
RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffd55911daf R14: 00007f366c73c9c0 R15: 000000000118cf4c
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