WARNING in cleanup_mnt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=162a5862f00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=f85175aedcd5a9d1b375
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f85175...@syzkaller.appspotmail.com

RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f6fb7611fe0
RBP: 00007f6fb7612020 R08: 00007f6fb7612020 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000
R13: 0000000020000100 R14: 00007f6fb7611fe0 R15: 0000000020047a20
------------[ cut here ]------------
WARNING: CPU: 0 PID: 32370 at fs/namespace.c:1093 cleanup_mnt.cold+0x11/0x18 fs/namespace.c:1093
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 32370 Comm: syz-executor.0 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
panic+0x26a/0x50e kernel/panic.c:186
__warn.cold+0x20/0x5a kernel/panic.c:541
report_bug+0x262/0x2b0 lib/bug.c:183
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x1d7/0x310 arch/x86/kernel/traps.c:296
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:cleanup_mnt.cold+0x11/0x18 fs/namespace.c:1093
Code: ee 48 c7 c7 e0 c1 74 88 c6 05 8d 44 32 03 01 e8 67 ec fe ff e9 87 70 b5 f9 e8 f2 ba 6d f9 48 c7 c7 a0 c3 74 88 e8 51 ec fe ff <0f> 0b e9 9f bf b5 f9 e8 da ba 6d f9 48 c7 c7 80 c8 74 88 c6 05 5c
RSP: 0018:ffff88809ba7fd48 EFLAGS: 00010286
RAX: 0000000000000024 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814dff01 RDI: ffffed101374ff9b
RBP: 0000000000000008 R08: 0000000000000024 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: ffff8880a3587800
R13: 0000000000000001 R14: 0000000000000007 R15: 0000000000000002
task_work_run+0x148/0x1c0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xbf3/0x2be0 kernel/exit.c:870
__do_sys_exit kernel/exit.c:936 [inline]
__se_sys_exit kernel/exit.c:934 [inline]
__x64_sys_exit+0x3e/0x50 kernel/exit.c:934
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7ff4d608e0e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff4d4a03118 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 00007ff4d61a0f60 RCX: 00007ff4d608e0e9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ff4d60e808d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffed5eefd0f R14: 00007ff4d4a03300 R15: 0000000000022000
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.