syzbot has found a reproducer for the following issue on: HEAD commit: feb9c5e19e91 Merge tag 'for_linus' of git://git.kernel.org.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=10ea9d8ef00000 kernel config: https://syzkaller.appspot.com/x/.config?x=79caa0035f59d385 dashboard link: https://syzkaller.appspot.com/bug?extid=5b1e53987f858500ec00 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=125039fef00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17a27b71f00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+5b1e53987f858500ec00@xxxxxxxxxxxxxxxxxxxxxxxxx ------------[ cut here ]------------ WARNING: CPU: 0 PID: 3608 at fs/namespace.c:1236 mntput_no_expire+0xada/0xcd0 fs/namespace.c:1236 Modules linked in: CPU: 0 PID: 3608 Comm: syz-executor314 Not tainted 5.18.0-rc6-syzkaller-00009-gfeb9c5e19e91 #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:1236 Code: 30 84 c0 0f 84 b9 fe ff ff 3c 03 0f 8f b1 fe ff ff 4c 89 44 24 10 e8 45 50 e9 ff 4c 8b 44 24 10 e9 9d fe ff ff e8 56 bf 9d ff <0f> 0b e9 19 fd ff ff e8 4a bf 9d ff e8 b5 cf 91 07 31 ff 89 c5 89 RSP: 0018:ffffc900030ffcf0 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 1ffff9200061ffa4 RCX: 0000000000000000 RDX: ffff88807c859d80 RSI: ffffffff81db815a RDI: 0000000000000003 RBP: ffff88801bcbca80 R08: 0000000000000000 R09: ffffffff9006d90f R10: ffffffff81db7e71 R11: 0000000000000001 R12: 0000000000000008 R13: ffffc900030ffd40 R14: 00000000ffffffff R15: 0000000000000002 FS: 0000555556a0e300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555556a17628 CR3: 0000000071c9d000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> path_umount+0x7d4/0x1260 fs/namespace.c:1806 ksys_umount fs/namespace.c:1825 [inline] __do_sys_umount fs/namespace.c:1830 [inline] __se_sys_umount fs/namespace.c:1828 [inline] __x64_sys_umount+0x159/0x180 fs/namespace.c:1828 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fcc5b9cc2c7 Code: 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffcb4fdf1a8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcc5b9cc2c7 RDX: 00007ffcb4fdf269 RSI: 000000000000000a RDI: 00007ffcb4fdf260 RBP: 00007ffcb4fdf260 R08: 00000000ffffffff R09: 00007ffcb4fdf040 R10: 0000555556a0f693 R11: 0000000000000202 R12: 00007ffcb4fe02e0 R13: 0000555556a0f5f0 R14: 00007ffcb4fdf1d0 R15: 0000000000000002 </TASK>
