------------[ cut here ]------------
WARNING: CPU: 0 PID: 10446 at fs/namespace.c:1187 mntput_no_expire+0xada/0xcd0 fs/namespace.c:1187
Modules linked in:
CPU: 0 PID: 10446 Comm: syz-executor.2 Not tainted 5.14.0-next-20210908-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:mntput_no_expire+0xada/0xcd0 fs/namespace.c:1187
Code: 30 84 c0 0f 84 b9 fe ff ff 3c 03 0f 8f b1 fe ff ff 4c 89 44 24 10 e8 d5 3f ec ff 4c 8b 44 24 10 e9 9d fe ff ff e8 16 1b a6 ff <0f> 0b e9 19 fd ff ff e8 0a 1b a6 ff e8 c5 6b 62 07 31 ff 89 c5 89
RSP: 0018:ffffc900036cf9b8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 1ffff920006d9f3d RCX: 0000000000000000
RDX: ffff888073819c80 RSI: ffffffff81cff24a RDI: 0000000000000003
RBP: ffff88807a852900 R08: 0000000000000000 R09: ffffffff8fcfa92f
R10: ffffffff81cfef61 R11: 0000000000000000 R12: 0000000000000008
R13: ffffc900036cfa08 R14: 00000000ffffffff R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff4bf34f2c CR3: 0000000024070000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 mntput fs/namespace.c:1233 [inline]
 namespace_unlock+0x26b/0x410 fs/namespace.c:1452
 drop_collected_mounts fs/namespace.c:1935 [inline]
 put_mnt_ns fs/namespace.c:4344 [inline]
 put_mnt_ns+0x106/0x140 fs/namespace.c:4340
 free_nsproxy+0x43/0x4c0 kernel/nsproxy.c:191
 put_nsproxy include/linux/nsproxy.h:105 [inline]
 switch_task_namespaces+0xaf/0xd0 kernel/nsproxy.c:249
 do_exit+0xba9/0x2a30 kernel/exit.c:824
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2160 kernel/signal.c:2868
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 irqentry_exit_to_user_mode+0x5/0x40 kernel/entry/common.c:315
 exc_page_fault+0xc6/0x180 arch/x86/mm/fault.c:1534
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568
RIP: 0033:0x404677
Code: Unable to access opcode bytes at RIP 0x40464d.
RSP: 002b:00007f8c93afa330 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 000000000056bf80 RCX: 000000000056bf80
RDX: 00007f8c93afa340 RSI: ffffffffffffffb8 RDI: 000000000000000b
RBP: 000000000000000b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007fff4bf35dbf R14: 00007f8c93b19300 R15: 0000000000022000