BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop3]

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syzbot

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Aug 7, 2021, 6:00:27 PM8/7/21
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Hello,

syzbot found the following issue on:

HEAD commit: 6ca2f514c578 Linux 4.19.201
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15019121300000
kernel config: https://syzkaller.appspot.com/x/.config?x=e245acf152ace855
dashboard link: https://syzkaller.appspot.com/bug?extid=52f6e86e9afe3e71de8d
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+52f6e8...@syzkaller.appspotmail.com

RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 0000000000467b0a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f85046dd000
RBP: 00007f85046dd040 R08: 00007f85046dd040 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 00007f85046dd000 R15: 0000000020010a00
BUG: Dentry 000000001c4c0090{i=0,n=/} still in use (-128) [unmount of erofs loop3]
------------[ cut here ]------------
WARNING: CPU: 1 PID: 19941 at fs/dcache.c:1518 umount_check fs/dcache.c:1518 [inline]
WARNING: CPU: 1 PID: 19941 at fs/dcache.c:1518 umount_check.cold+0xf2/0x116 fs/dcache.c:1499
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 19941 Comm: syz-executor.3 Not tainted 4.19.201-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:umount_check fs/dcache.c:1518 [inline]
RIP: 0010:umount_check.cold+0xf2/0x116 fs/dcache.c:1499
Code: f9 4d 89 f1 45 89 e0 48 89 e9 41 55 4c 89 fa 48 89 ee 48 c7 c7 c0 a7 74 88 e8 99 f0 fe ff 48 c7 c7 c0 a6 74 88 e8 8d f0 fe ff <0f> 0b 58 e9 ee 16 b4 f9 e8 2a c3 a3 f9 e9 22 ff ff ff 48 89 df e8
RSP: 0018:ffff88803bd9fa98 EFLAGS: 00010286
RAX: 0000000000000024 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff814dfd61 RDI: ffffed10077b3f45
RBP: ffff8880903f9dc0 R08: 0000000000000024 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 00000000ffffff80
R13: ffff888045b20850 R14: ffffffff893f9a40 R15: 0000000000000000
d_walk+0x196/0x990 fs/dcache.c:1253
do_one_tree fs/dcache.c:1525 [inline]
shrink_dcache_for_umount+0x87/0x330 fs/dcache.c:1541
generic_shutdown_super+0x68/0x370 fs/super.c:441
kill_block_super+0x97/0xf0 fs/super.c:1185
deactivate_locked_super+0x94/0x160 fs/super.c:329
mount_bdev+0x373/0x3b0 fs/super.c:1160
erofs_mount+0x8c/0xc0 drivers/staging/erofs/super.c:512
mount_fs+0xa3/0x310 fs/super.c:1261
vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
vfs_kern_mount fs/namespace.c:951 [inline]
do_new_mount fs/namespace.c:2469 [inline]
do_mount+0x113c/0x2f10 fs/namespace.c:2799
ksys_mount+0xcf/0x130 fs/namespace.c:3015
__do_sys_mount fs/namespace.c:3029 [inline]
__se_sys_mount fs/namespace.c:3026 [inline]
__x64_sys_mount+0xba/0x150 fs/namespace.c:3026
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x467b0a
Code: 48 c7 c2 bc ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 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:00007f85046dcfa8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 0000000000467b0a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f85046dd000
RBP: 00007f85046dd040 R08: 00007f85046dd040 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 00007f85046dd000 R15: 0000000020010a00
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot

unread,
Aug 7, 2021, 6:49:27 PM8/7/21
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:

HEAD commit: 6ca2f514c578 Linux 4.19.201
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13b455d6300000
kernel config: https://syzkaller.appspot.com/x/.config?x=e245acf152ace855
dashboard link: https://syzkaller.appspot.com/bug?extid=52f6e86e9afe3e71de8d
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17b63904300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=149950be300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+52f6e8...@syzkaller.appspotmail.com

RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe510d3c30
RBP: 00007ffe510d3c30 R08: 00007ffe510d3c70 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000020000248
R13: 0000000000000005 R14: 0000000000000006 R15: 0000000000000003
CPU: 1 PID: 8116 Comm: syz-executor194 Not tainted 4.19.201-syzkaller #0
BUG: Dentry 0000000020277614{i=0,n=/} still in use (-128) [unmount of erofs loop3]
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
fail_dump lib/fault-inject.c:51 [inline]
should_fail.cold+0xa/0xf lib/fault-inject.c:149
__should_failslab+0x115/0x180 mm/failslab.c:32
should_failslab+0x5/0x10 mm/slab_common.c:1590
------------[ cut here ]------------
slab_pre_alloc_hook mm/slab.h:424 [inline]
slab_alloc mm/slab.c:3383 [inline]
kmem_cache_alloc+0x277/0x370 mm/slab.c:3557
erofs_read_super drivers/staging/erofs/super.c:414 [inline]
erofs_fill_super+0x10a1/0x12cc drivers/staging/erofs/super.c:499
WARNING: CPU: 0 PID: 8115 at fs/dcache.c:1518 umount_check fs/dcache.c:1518 [inline]
WARNING: CPU: 0 PID: 8115 at fs/dcache.c:1518 umount_check.cold+0xf2/0x116 fs/dcache.c:1499
Kernel panic - not syncing: panic_on_warn set ...

mount_bdev+0x2fc/0x3b0 fs/super.c:1158
erofs_mount+0x8c/0xc0 drivers/staging/erofs/super.c:512
mount_fs+0xa3/0x310 fs/super.c:1261
vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
vfs_kern_mount fs/namespace.c:951 [inline]
do_new_mount fs/namespace.c:2469 [inline]
do_mount+0x113c/0x2f10 fs/namespace.c:2799
ksys_mount+0xcf/0x130 fs/namespace.c:3015
__do_sys_mount fs/namespace.c:3029 [inline]
__se_sys_mount fs/namespace.c:3026 [inline]
__x64_sys_mount+0xba/0x150 fs/namespace.c:3026
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445f0a
Code: 48 c7 c2 c0 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 a8 00 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 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:00007ffe510d3c18 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe510d3c70 RCX: 0000000000445f0a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe510d3c30
RBP: 00007ffe510d3c30 R08: 00007ffe510d3c70 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000020000248
R13: 0000000000000005 R14: 0000000000000006 R15: 0000000000000003
CPU: 0 PID: 8115 Comm: syz-executor194 Not tainted 4.19.201-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:umount_check fs/dcache.c:1518 [inline]
RIP: 0010:umount_check.cold+0xf2/0x116 fs/dcache.c:1499
Code: f9 4d 89 f1 45 89 e0 48 89 e9 41 55 4c 89 fa 48 89 ee 48 c7 c7 c0 a7 74 88 e8 99 f0 fe ff 48 c7 c7 c0 a6 74 88 e8 8d f0 fe ff <0f> 0b 58 e9 ee 16 b4 f9 e8 2a c3 a3 f9 e9 22 ff ff ff 48 89 df e8
RSP: 0018:ffff8880b14c7a98 EFLAGS: 00010286
RAX: 0000000000000024 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814dfd61 RDI: ffffed1016298f45
RBP: ffff8880a2e452c0 R08: 0000000000000024 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 00000000ffffff80
R13: ffff8880b006af10 R14: ffffffff893f9a40 R15: 0000000000000000
d_walk+0x196/0x990 fs/dcache.c:1253
do_one_tree fs/dcache.c:1525 [inline]
shrink_dcache_for_umount+0x87/0x330 fs/dcache.c:1541
generic_shutdown_super+0x68/0x370 fs/super.c:441
kill_block_super+0x97/0xf0 fs/super.c:1185
deactivate_locked_super+0x94/0x160 fs/super.c:329
mount_bdev+0x373/0x3b0 fs/super.c:1160
erofs_mount+0x8c/0xc0 drivers/staging/erofs/super.c:512
BUG: Dentry 0000000090c8f336{i=0,n=/} still in use (-128) [unmount of erofs loop5]
------------[ cut here ]------------
mount_fs+0xa3/0x310 fs/super.c:1261
WARNING: CPU: 1 PID: 8116 at fs/dcache.c:1518 umount_check fs/dcache.c:1518 [inline]
WARNING: CPU: 1 PID: 8116 at fs/dcache.c:1518 umount_check.cold+0xf2/0x116 fs/dcache.c:1499
vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
Modules linked in:
vfs_kern_mount fs/namespace.c:951 [inline]
do_new_mount fs/namespace.c:2469 [inline]
do_mount+0x113c/0x2f10 fs/namespace.c:2799
CPU: 1 PID: 8116 Comm: syz-executor194 Not tainted 4.19.201-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:umount_check fs/dcache.c:1518 [inline]
RIP: 0010:umount_check.cold+0xf2/0x116 fs/dcache.c:1499
Code: f9 4d 89 f1 45 89 e0 48 89 e9 41 55 4c 89 fa 48 89 ee 48 c7 c7 c0 a7 74 88 e8 99 f0 fe ff 48 c7 c7 c0 a6 74 88 e8 8d f0 fe ff <0f> 0b 58 e9 ee 16 b4 f9 e8 2a c3 a3 f9 e9 22 ff ff ff 48 89 df e8
RSP: 0018:ffff88809567fa98 EFLAGS: 00010286
RAX: 0000000000000024 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814dfd61 RDI: ffffed1012acff45
ksys_mount+0xcf/0x130 fs/namespace.c:3015
RBP: ffff8880b54e1e40 R08: 0000000000000024 R09: 0000000000000000
__do_sys_mount fs/namespace.c:3029 [inline]
__se_sys_mount fs/namespace.c:3026 [inline]
__x64_sys_mount+0xba/0x150 fs/namespace.c:3026
R10: 0000000000000005 R11: 0000000000000000 R12: 00000000ffffff80
R13: ffff8880b0114f50 R14: ffffffff893f9a40 R15: 0000000000000000
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
FS: 0000000002156300(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
entry_SYSCALL_64_after_hwframe+0x49/0xbe
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
RIP: 0033:0x445f0a
CR2: 00007f33554a2000 CR3: 00000000a5ec1000 CR4: 00000000001406e0
Code: 48 c7 c2 c0 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 a8 00 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 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
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
RSP: 002b:00007ffe510d3c18 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
RAX: ffffffffffffffda RBX: 00007ffe510d3c70 RCX: 0000000000445f0a
Call Trace:
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe510d3c30
d_walk+0x196/0x990 fs/dcache.c:1253
RBP: 00007ffe510d3c30 R08: 00007ffe510d3c70 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000020000248
R13: 0000000000000005 R14: 0000000000000006 R15: 0000000000000003
do_one_tree fs/dcache.c:1525 [inline]
shrink_dcache_for_umount+0x87/0x330 fs/dcache.c:1541
generic_shutdown_super+0x68/0x370 fs/super.c:441
kill_block_super+0x97/0xf0 fs/super.c:1185
deactivate_locked_super+0x94/0x160 fs/super.c:329
mount_bdev+0x373/0x3b0 fs/super.c:1160
erofs_mount+0x8c/0xc0 drivers/staging/erofs/super.c:512
mount_fs+0xa3/0x310 fs/super.c:1261
vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
vfs_kern_mount fs/namespace.c:951 [inline]
do_new_mount fs/namespace.c:2469 [inline]
do_mount+0x113c/0x2f10 fs/namespace.c:2799
ksys_mount+0xcf/0x130 fs/namespace.c:3015
__do_sys_mount fs/namespace.c:3029 [inline]
__se_sys_mount fs/namespace.c:3026 [inline]
__x64_sys_mount+0xba/0x150 fs/namespace.c:3026
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445f0a
Code: 48 c7 c2 c0 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 a8 00 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 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:00007ffe510d3c18 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe510d3c70 RCX: 0000000000445f0a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe510d3c30
RBP: 00007ffe510d3c30 R08: 00007ffe510d3c70 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000020000248
R13: 0000000000000005 R14: 0000000000000006 R15: 0000000000000003
irq event stamp: 2198
hardirqs last enabled at (2197): [<ffffffff81003ce4>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (2198): [<ffffffff81003d00>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last enabled at (2196): [<ffffffff88400678>] __do_softirq+0x678/0x980 kernel/softirq.c:318
softirqs last disabled at (2185): [<ffffffff81392705>] invoke_softirq kernel/softirq.c:372 [inline]
softirqs last disabled at (2185): [<ffffffff81392705>] irq_exit+0x215/0x260 kernel/softirq.c:412
---[ end trace 0fe773ca502d0de0 ]---
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