------------[ cut here ]------------
ida_free called for id=1555 which is not allocated.
WARNING: CPU: 0 PID: 6590 at lib/idr.c:592 ida_free+0x280/0x310
Modules linked in:
CPU: 0 UID: 0 PID: 6590 Comm: syz.0.180 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:ida_free+0x280/0x310
Code: 00 00 00 00 fc ff df 48 8b 5c 24 10 48 8b 7c 24 40 48 89 de e8 d1 8a 0c 00 90 48 c7 c7 80 ee ba 8c 44 89 fe e8 11 87 12 f6 90 <0f> 0b 90 90 eb 34 e8 95 02 4f f6 49 bd 00 00 00 00 00 fc ff df eb
RSP: 0018:ffffc900047cf860 EFLAGS: 00010246
RAX: 0d5b56ce084feb00 RBX: 0000000000000a02 RCX: ffff8880339b3980
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc900047cf960 R08: ffff88804b024293 R09: 1ffff11009604852
R10: dffffc0000000000 R11: ffffed1009604853 R12: 1ffff920008f9f10
R13: dffffc0000000000 R14: ffff8881064e4600 R15: 0000000000000613
FS:  00007ff74b9036c0(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5f0f7b4d58 CR3: 0000000035db0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 free_mnt_ns+0x6d/0x110
 namespace_unlock+0x529/0x760
 free_nsproxy+0x3e/0x350
 do_exit+0x6b0/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff74a98eba9
Code: Unable to access opcode bytes at 0x7ff74a98eb7f.
RSP: 002b:00007ff74b9030e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007ff74abd5fa8 RCX: 00007ff74a98eba9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007ff74abd5fa8
RBP: 00007ff74abd5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff74abd6038 R14: 00007ffd81090540 R15: 00007ffd81090628
 </TASK>
