BUG: Dentry still in use [unmount of tmpfs tmpfs]

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1e5f5a14 ANDROID: x86: Add objtool to MAKE_GOALS
git tree: android12-5.4
console output: https://syzkaller.appspot.com/x/log.txt?x=1208d88cd00000
kernel config: https://syzkaller.appspot.com/x/.config?x=7dc3dec9bdddbf39
dashboard link: https://syzkaller.appspot.com/bug?extid=d4aeb09e24a56864701f
compiler: Android (6032204 based on r370808) clang version 10.0.1 (https://android.googlesource.com/toolchain/llvm-project 6e765c10313d15c02ab29977a82938f66742c3a9)

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+d4aeb0...@syzkaller.appspotmail.com

BUG: Dentry 00000000feeeb45b{i=0,n=.index} still in use (1) [unmount of tmpfs tmpfs]
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1914 at fs/dcache.c:1597 umount_check+0x179/0x1c0 fs/dcache.c:1588
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 1914 Comm: syz-executor.3 Not tainted 5.4.93-syzkaller-00590-g1e5f5a14faba #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+0x1dd/0x24e lib/dump_stack.c:118
panic+0x285/0x750 kernel/panic.c:221
__warn+0x1fd/0x200 kernel/panic.c:582
report_bug+0x390/0x4d0 lib/bug.c:195
fixup_bug arch/x86/kernel/traps.c:179 [inline]
do_error_trap arch/x86/kernel/traps.c:272 [inline]
do_invalid_op+0x6e/0x110 arch/x86/kernel/traps.c:291
invalid_op+0x1e/0x30 arch/x86/entry/entry_64.S:1029
RIP: 0010:umount_check+0x179/0x1c0 fs/dcache.c:1588
Code: ff 4c 8b 0b 48 81 c5 20 04 00 00 48 c7 c7 63 55 1d 85 4c 89 fe 4c 89 f2 4c 89 f9 45 89 e8 31 c0 55 e8 07 36 b0 ff 48 83 c4 08 <0f> 0b e9 fd fe ff ff 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c d4 fe ff
RSP: 0018:ffff8881e4857c68 EFLAGS: 00010282
RAX: 0000000000000055 RBX: ffffffff8546c8a0 RCX: a888aa48c249dd00
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffff8881df62d420 R08: ffffffff814e47a1 R09: ffffed103ee05e08
R10: ffffed103ee05e08 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffff8881a54d9990
d_walk+0x2e9/0x570 fs/dcache.c:1307
do_one_tree fs/dcache.c:1604 [inline]
shrink_dcache_for_umount+0x8a/0x1b0 fs/dcache.c:1620
generic_shutdown_super+0x63/0x2a0 fs/super.c:447
kill_anon_super fs/super.c:1108 [inline]
kill_litter_super+0x71/0xa0 fs/super.c:1117
deactivate_locked_super+0xaf/0x100 fs/super.c:335
deactivate_super+0x1b8/0x280 fs/super.c:366
cleanup_mnt+0x432/0x4e0 fs/namespace.c:1102
task_work_run+0x176/0x1a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop arch/x86/entry/common.c:163 [inline]
prepare_exit_to_usermode+0x2b0/0x310 arch/x86/entry/common.c:194
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x466f67
Code: ff d0 48 89 c7 b8 3c 00 00 00 0f 05 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffee5dd99b8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000466f67
RDX: 00007ffee5dd9a8b RSI: 0000000000000002 RDI: 00007ffee5dd9a80
RBP: 00007ffee5dd9a80 R08: 00000000ffffffff R09: 00007ffee5dd9850
R10: 0000000001b7f793 R11: 0000000000000206 R12: 00000000004af4e4
R13: 00007ffee5ddab50 R14: 0000000001b7f6f0 R15: 00007ffee5ddab90
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 1e5f5a14 ANDROID: x86: Add objtool to MAKE_GOALS
git tree: android12-5.4

console output: https://syzkaller.appspot.com/x/log.txt?x=104dc1d8d00000

kernel config: https://syzkaller.appspot.com/x/.config?x=7dc3dec9bdddbf39
dashboard link: https://syzkaller.appspot.com/bug?extid=d4aeb09e24a56864701f
compiler: Android (6032204 based on r370808) clang version 10.0.1 (https://android.googlesource.com/toolchain/llvm-project 6e765c10313d15c02ab29977a82938f66742c3a9)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=161b50f8d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=109288c4d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d4aeb0...@syzkaller.appspotmail.com

BUG: Dentry 000000009fb05929{i=0,n=.index} still in use (1) [unmount of tmpfs tmpfs]
------------[ cut here ]------------
WARNING: CPU: 1 PID: 364 at fs/dcache.c:1597 umount_check+0x179/0x1c0 fs/dcache.c:1588

Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 364 Comm: syz-executor417 Not tainted 5.4.93-syzkaller-00590-g1e5f5a14faba #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+0x1dd/0x24e lib/dump_stack.c:118
panic+0x285/0x750 kernel/panic.c:221
__warn+0x1fd/0x200 kernel/panic.c:582
report_bug+0x390/0x4d0 lib/bug.c:195
fixup_bug arch/x86/kernel/traps.c:179 [inline]
do_error_trap arch/x86/kernel/traps.c:272 [inline]
do_invalid_op+0x6e/0x110 arch/x86/kernel/traps.c:291
invalid_op+0x1e/0x30 arch/x86/entry/entry_64.S:1029
RIP: 0010:umount_check+0x179/0x1c0 fs/dcache.c:1588
Code: ff 4c 8b 0b 48 81 c5 20 04 00 00 48 c7 c7 63 55 1d 85 4c 89 fe 4c 89 f2 4c 89 f9 45 89 e8 31 c0 55 e8 07 36 b0 ff 48 83 c4 08 <0f> 0b e9 fd fe ff ff 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c d4 fe ff

RSP: 0018:ffff8881e8837708 EFLAGS: 00010282
RAX: 0000000000000055 RBX: ffffffff8546c8a0 RCX: a3b0bfbbf6f45b00

RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000

RBP: ffff8881e8825420 R08: ffffffff814e47a1 R09: ffffed103ee25e08
R10: ffffed103ee25e08 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffff8881effd7110

d_walk+0x2e9/0x570 fs/dcache.c:1307
do_one_tree fs/dcache.c:1604 [inline]
shrink_dcache_for_umount+0x8a/0x1b0 fs/dcache.c:1620
generic_shutdown_super+0x63/0x2a0 fs/super.c:447
kill_anon_super fs/super.c:1108 [inline]
kill_litter_super+0x71/0xa0 fs/super.c:1117
deactivate_locked_super+0xaf/0x100 fs/super.c:335
deactivate_super+0x1b8/0x280 fs/super.c:366
cleanup_mnt+0x432/0x4e0 fs/namespace.c:1102
task_work_run+0x176/0x1a0 kernel/task_work.c:113

exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xcc2/0x2830 kernel/exit.c:812
do_group_exit+0x155/0x2b0 kernel/exit.c:910
get_signal+0x13ec/0x1f00 kernel/signal.c:2745
do_signal+0x92/0x5d0 arch/x86/kernel/signal.c:815
exit_to_usermode_loop arch/x86/entry/common.c:159 [inline]
prepare_exit_to_usermode+0x207/0x310 arch/x86/entry/common.c:194
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x449f69
Code: Bad RIP value.
RSP: 002b:00007f3bb7b212f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000004cb4d0 RCX: 0000000000449f69
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000004cb4d8
RBP: 6e656d6572636e69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 766974616c65723d R14: 65646f6e695f726e R15: 00000000004cb4d8

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.