[v6.1] possible deadlock in chown_common

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a456e1743881 Linux 6.1.39
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1643c4c6a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e6478d39ceccfae
dashboard link: https://syzkaller.appspot.com/bug?extid=ad704706dcfb2c04070a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/47260b2456c0/disk-a456e174.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ac087687a80a/vmlinux-a456e174.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e2c3d9e7236f/Image-a456e174.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ad7047...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.1.39-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/11206 is trying to acquire lock:
ffff000102213140 (&type->i_mutex_dir_key#21){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff000102213140 (&type->i_mutex_dir_key#21){+.+.}-{3:3}, at: chown_common+0x358/0x7d8 fs/open.c:726

but task is already holding lock:
ffff000102c3c460 (sb_writers#25){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#25){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1832 [inline]
sb_start_write+0x7c/0x308 include/linux/fs.h:1907
mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437
reiserfs_ioctl+0x184/0x454 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #1 (&sbi->lock){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364
__lookup_slow+0x250/0x374 fs/namei.c:1685
lookup_one_len+0x178/0x28c fs/namei.c:2711
reiserfs_lookup_privroot+0x8c/0x204 fs/reiserfs/xattr.c:973
reiserfs_fill_super+0x1bc0/0x2028 fs/reiserfs/super.c:2174
mount_bdev+0x274/0x370 fs/super.c:1423
get_super_block+0x44/0x58 fs/reiserfs/super.c:2601
legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
vfs_get_tree+0x90/0x274 fs/super.c:1553
do_new_mount+0x25c/0x8c4 fs/namespace.c:3040
path_mount+0x590/0xe58 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x45c/0x594 fs/namespace.c:3568
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #0 (&type->i_mutex_dir_key#21){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:756 [inline]
chown_common+0x358/0x7d8 fs/open.c:726
vfs_fchown fs/open.c:804 [inline]
ksys_fchown+0xe0/0x158 fs/open.c:815
__do_sys_fchown fs/open.c:823 [inline]
__se_sys_fchown fs/open.c:821 [inline]
__arm64_sys_fchown+0x7c/0x94 fs/open.c:821
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

other info that might help us debug this:

Chain exists of:
&type->i_mutex_dir_key#21 --> &sbi->lock --> sb_writers#25

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sb_writers#25);
lock(&sbi->lock);
lock(sb_writers#25);
lock(&type->i_mutex_dir_key#21);

*** DEADLOCK ***

1 lock held by syz-executor.4/11206:
#0: ffff000102c3c460 (sb_writers#25){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437

stack backtrace:
CPU: 0 PID: 11206 Comm: syz-executor.4 Not tainted 6.1.39-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2056
check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:756 [inline]
chown_common+0x358/0x7d8 fs/open.c:726
vfs_fchown fs/open.c:804 [inline]
ksys_fchown+0xe0/0x158 fs/open.c:815
__do_sys_fchown fs/open.c:823 [inline]
__se_sys_fchown fs/open.c:821 [inline]
__arm64_sys_fchown+0x7c/0x94 fs/open.c:821
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to change bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

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