general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
CPU: 0 PID: 14725 Comm: syz-executor.2 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:workqueue_sysfs_unregister kernel/workqueue.c:5691 [inline]
RIP: 0010:destroy_workqueue+0x2e/0x6b0 kernel/workqueue.c:4351
Code: 49 89 fe 41 55 41 54 55 53 48 83 ec 08 e8 8a 6a 26 00 49 8d be 08 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 05 00 00 49 8b 9e 08 01 00 00 48 85 db 74 19
RSP: 0018:ffffc90009067a28 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: ffffc9000e439000
RDX: 0000000000000021 RSI: ffffffff814c2af6 RDI: 0000000000000108
RBP: ffff888218ac30f0 R08: ffff888051fe8280 R09: fffffbfff185270a
R10: fffffbfff1852709 R11: ffffffff8c29384f R12: ffff888218ac3000
R13: ffff88808b101ae0 R14: 0000000000000000 R15: ffff88808b1018c0
FS:  00007f317c7bd700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb72444fdb8 CR3: 00000000906e7000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 loop_unprepare_queue drivers/block/loop.c:891 [inline]
 __loop_clr_fd+0x185/0x1280 drivers/block/loop.c:1210
 lo_release+0x1ad/0x1e7 drivers/block/loop.c:1928
 __blkdev_put+0x509/0x690 fs/block_dev.c:1896
 blkdev_close+0x86/0xb0 fs/block_dev.c:1965
 __fput+0x2da/0x850 fs/file_table.c:280
 task_work_run+0x13f/0x1b0 kernel/task_work.c:113
 get_signal+0x2054/0x24e0 kernel/signal.c:2533
 do_signal+0x7e/0x13f0 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x672/0x790 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c849
Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f317c7bcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007f317c7bd6d4 RCX: 000000000045c849
RDX: 0000000000000004 RSI: 0000000000004c00 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000003e9 R14: 00000000004c67cf R15: 000000000076bf0c
Modules linked in:
---[ end trace 7f5dc8bd964df782 ]---
RIP: 0010:workqueue_sysfs_unregister kernel/workqueue.c:5691 [inline]
RIP: 0010:destroy_workqueue+0x2e/0x6b0 kernel/workqueue.c:4351
Code: 49 89 fe 41 55 41 54 55 53 48 83 ec 08 e8 8a 6a 26 00 49 8d be 08 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 05 00 00 49 8b 9e 08 01 00 00 48 85 db 74 19
RSP: 0018:ffffc90009067a28 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: ffffc9000e439000
RDX: 0000000000000021 RSI: ffffffff814c2af6 RDI: 0000000000000108
RBP: ffff888218ac30f0 R08: ffff888051fe8280 R09: fffffbfff185270a
R10: fffffbfff1852709 R11: ffffffff8c29384f R12: ffff888218ac3000
R13: ffff88808b101ae0 R14: 0000000000000000 R15: ffff88808b1018c0
FS:  00007f317c7bd700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001d5a978 CR3: 00000000906e7000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400