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kernel BUG at fs/userfaultfd.c:883!
invalid opcode: 0000 [#1] SMP KASAN
CPU: 0 PID: 19687 Comm: syz-executor0 Not tainted 4.18.0-rc4+ #148
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:userfaultfd_release+0x5fb/0x770 fs/userfaultfd.c:882
Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 a1 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 be a0 ff <0f> 0b 4c 89 f7 e8 0b 9e de ff e9 11 fc ff ff 4c 89 e7 e8 5e 9d de 
RSP: 0018:ffff880199b97a80 EFLAGS: 00010293
RAX: ffff88019ab74100 RBX: dffffc0000000000 RCX: ffffffff81db4a59
RDX: 0000000000000000 RSI: ffffffff81db4ccb RDI: 0000000000000000
RBP: ffff880199b97bd0 R08: ffff88019ab74100 R09: 0000000000000000
R10: ffff88019ab74938 R11: b21129c27367def3 R12: ffff8801be46e148
R13: 0000000000000000 R14: ffff8801b234f250 R15: 0000000000000000
FS:  0000000002539940(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb63009ec88 CR3: 00000001c3ff8000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __fput+0x355/0x8b0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:192 [inline]
 exit_to_usermode_loop+0x313/0x370 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x40fb91
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 19 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 
RSP: 002b:0000000000a3eab0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000017 RCX: 000000000040fb91
RDX: 0000000000000000 RSI: 0000000000730e80 RDI: 0000000000000016
RBP: 0000000000000013 R08: 0000000000a3ea30 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000a3f160 R15: 00000000007034c0
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace e18762a4adc3080c ]---
RIP: 0010:userfaultfd_release+0x5fb/0x770 fs/userfaultfd.c:882
Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 a1 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 be a0 ff <0f> 0b 4c 89 f7 e8 0b 9e de ff e9 11 fc ff ff 4c 89 e7 e8 5e 9d de 
RSP: 0018:ffff880199b97a80 EFLAGS: 00010293
RAX: ffff88019ab74100 RBX: dffffc0000000000 RCX: ffffffff81db4a59
RDX: 0000000000000000 RSI: ffffffff81db4ccb RDI: 0000000000000000
RBP: ffff880199b97bd0 R08: ffff88019ab74100 R09: 0000000000000000
R10: ffff88019ab74938 R11: b21129c27367def3 R12: ffff8801be46e148
R13: 0000000000000000 R14: ffff8801b234f250 R15: 0000000000000000
FS:  0000000002539940(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb63009ec88 CR3: 00000001c3ff8000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400