general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f] CPU: 1 PID: 15047 Comm: blkid 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:ffffc90007607c30 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000 RDX: 0000000000000021 RSI: ffffffff814c2af6 RDI: 0000000000000108 RBP: ffff8880a24f98f0 R08: ffff888051192480 R09: fffffbfff185270a R10: fffffbfff1852709 R11: ffffffff8c29384f R12: ffff8880a24f9800 R13: ffff8880a534f320 R14: 0000000000000000 R15: ffff8880a534f100 FS: 00007f7b784f2740(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffab53afc8 CR3: 00000000a03c6000 CR4: 00000000001406e0 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 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165 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: 0033:0x7f7b77dfa2b0 Code: 40 75 0b 31 c0 48 83 c4 08 e9 0c ff ff ff 48 8d 3d c5 32 08 00 e8 c0 07 02 00 83 3d 45 a3 2b 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ce 8a 01 00 48 89 04 24 RSP: 002b:00007fffab53da48 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f7b77dfa2b0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000010d2030 R13: 0000000000000000 R14: 0000000000000003 R15: 0000000000000005 Modules linked in: ---[ end trace 45340941ae0febd8 ]--- 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:ffffc90007607c30 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000 RDX: 0000000000000021 RSI: ffffffff814c2af6 RDI: 0000000000000108 RBP: ffff8880a24f98f0 R08: ffff888051192480 R09: fffffbfff185270a R10: fffffbfff1852709 R11: ffffffff8c29384f R12: ffff8880a24f9800 R13: ffff8880a534f320 R14: 0000000000000000 R15: ffff8880a534f100 FS: 00007f7b784f2740(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000000a03c6000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400