[v5.15] possible deadlock in filename_create

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2ddbd0f967b3 Linux 5.15.102
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13326bc6c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=fec083380faceb1e
dashboard link: https://syzkaller.appspot.com/bug?extid=01e6f5ccff55ee65b0d5
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/156d2aa91f3c/disk-2ddbd0f9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f0e97f5be5fb/vmlinux-2ddbd0f9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/20d0a55a041d/bzImage-2ddbd0f9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+01e6f5...@syzkaller.appspotmail.com

reiserfs: enabling write barrier flush mode
REISERFS (device loop2): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
5.15.102-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/16638 is trying to acquire lock:
ffff88802c142090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x76/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff88802e4c9020 (&type->i_mutex_dir_key#16/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
ffff88802e4c9020 (&type->i_mutex_dir_key#16/1){+.+.}-{3:3}, at: filename_create+0x256/0x530 fs/namei.c:3708

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&type->i_mutex_dir_key#16/1){+.+.}-{3:3}:
lock_acquire+0x1ff/0x570 kernel/locking/lockdep.c:5622
down_write_nested+0xa0/0x180 kernel/locking/rwsem.c:1657
inode_lock_nested include/linux/fs.h:822 [inline]
filename_create+0x256/0x530 fs/namei.c:3708
do_mkdirat+0xbd/0x4c0 fs/namei.c:3952
__do_sys_mkdir fs/namei.c:3983 [inline]
__se_sys_mkdir fs/namei.c:3981 [inline]
__x64_sys_mkdir+0x6a/0x80 fs/namei.c:3981
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #1 (sb_writers#21){.+.+}-{0:0}:
lock_acquire+0x1ff/0x570 kernel/locking/lockdep.c:5622
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1742 [inline]
sb_start_write+0x4f/0x1c0 include/linux/fs.h:1812
mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:421
reiserfs_ioctl+0x170/0x340 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #0 (&sbi->lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
lock_acquire+0x1ff/0x570 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
reiserfs_write_lock+0x76/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x15c/0x4b0 fs/reiserfs/namei.c:364
__lookup_hash+0x117/0x240 fs/namei.c:1560
filename_create+0x28d/0x530 fs/namei.c:3709
do_mkdirat+0xbd/0x4c0 fs/namei.c:3952
__do_sys_mkdir fs/namei.c:3983 [inline]
__se_sys_mkdir fs/namei.c:3981 [inline]
__x64_sys_mkdir+0x6a/0x80 fs/namei.c:3981
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

other info that might help us debug this:

Chain exists of:
&sbi->lock --> sb_writers#21 --> &type->i_mutex_dir_key#16/1

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&type->i_mutex_dir_key#16/1);
lock(sb_writers#21);
lock(&type->i_mutex_dir_key#16/1);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor.2/16638:
#0: ffff88807dfe2460 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:377
#1: ffff88802e4c9020 (&type->i_mutex_dir_key#16/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
#1: ffff88802e4c9020 (&type->i_mutex_dir_key#16/1){+.+.}-{3:3}, at: filename_create+0x256/0x530 fs/namei.c:3708

stack backtrace:
CPU: 1 PID: 16638 Comm: syz-executor.2 Not tainted 5.15.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
lock_acquire+0x1ff/0x570 kernel/locking/lockdep.c:5622
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
reiserfs_write_lock+0x76/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x15c/0x4b0 fs/reiserfs/namei.c:364
__lookup_hash+0x117/0x240 fs/namei.c:1560
filename_create+0x28d/0x530 fs/namei.c:3709
do_mkdirat+0xbd/0x4c0 fs/namei.c:3952
__do_sys_mkdir fs/namei.c:3983 [inline]
__se_sys_mkdir fs/namei.c:3981 [inline]
__x64_sys_mkdir+0x6a/0x80 fs/namei.c:3981
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f74d6e0b0f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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:00007f74d537d168 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007f74d6f2af80 RCX: 00007f74d6e0b0f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180
RBP: 00007f74d6e66b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd87b7496f R14: 00007f74d537d300 R15: 0000000000022000
</TASK>
overlayfs: upper fs needs to support d_type.
overlayfs: upper fs does not support tmpfile.
overlayfs: upper fs does not support RENAME_WHITEOUT.
overlayfs: failed to set xattr on upper
overlayfs: ...falling back to index=off,metacopy=off.


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[syzbot]

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