[v6.1] possible deadlock in filename_create

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e3a87a10f259 Linux 6.1.21
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10862a85c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=390800ef8aeebc47
dashboard link: https://syzkaller.appspot.com/bug?extid=3f64fe788a23ed032321
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9f5022ccd560/disk-e3a87a10.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f8524664c631/vmlinux-e3a87a10.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ad699b30c2c4/Image-e3a87a10.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3f64fe...@syzkaller.appspotmail.com

REISERFS warning (device loop3): jdm-20006 create_privroot: xattrs/ACLs enabled and couldn't find/create .reiserfs_priv. Failing mount.
======================================================
WARNING: possible circular locking dependency detected
6.1.21-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/18060 is trying to acquire lock:
ffff0000d253f090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff000131788980 (&type->i_mutex_dir_key#21/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
ffff000131788980 (&type->i_mutex_dir_key#21/1){+.+.}-{3:3}, at: filename_create+0x200/0x464 fs/namei.c:3807

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&type->i_mutex_dir_key#21/1){+.+.}-{3:3}:
down_write_nested+0x64/0x94 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:791 [inline]
filename_create+0x200/0x464 fs/namei.c:3807
do_symlinkat+0xd8/0x6b0 fs/namei.c:4420
__do_sys_symlinkat fs/namei.c:4447 [inline]
__se_sys_symlinkat fs/namei.c:4444 [inline]
__arm64_sys_symlinkat+0xa4/0xbc fs/namei.c:4444
__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 (sb_writers#29){.+.+}-{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

-> #0 (&sbi->lock){+.+.}-{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
__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_hash+0x108/0x230 fs/namei.c:1601
filename_create+0x22c/0x464 fs/namei.c:3808
do_symlinkat+0xd8/0x6b0 fs/namei.c:4420
__do_sys_symlinkat fs/namei.c:4447 [inline]
__se_sys_symlinkat fs/namei.c:4444 [inline]
__arm64_sys_symlinkat+0xa4/0xbc fs/namei.c:4444
__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:
&sbi->lock --> sb_writers#29 --> &type->i_mutex_dir_key#21/1

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&type->i_mutex_dir_key#21/1);
lock(sb_writers#29);
lock(&type->i_mutex_dir_key#21/1);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor.3/18060:
#0: ffff0000cd554460 (sb_writers#29){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393
#1: ffff000131788980 (&type->i_mutex_dir_key#21/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#1: ffff000131788980 (&type->i_mutex_dir_key#21/1){+.+.}-{3:3}, at: filename_create+0x200/0x464 fs/namei.c:3807

stack backtrace:
CPU: 1 PID: 18060 Comm: syz-executor.3 Not tainted 6.1.21-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
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/0x5c 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
__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_hash+0x108/0x230 fs/namei.c:1601
filename_create+0x22c/0x464 fs/namei.c:3808
do_symlinkat+0xd8/0x6b0 fs/namei.c:4420
__do_sys_symlinkat fs/namei.c:4447 [inline]
__se_sys_symlinkat fs/namei.c:4444 [inline]
__arm64_sys_symlinkat+0xa4/0xbc fs/namei.c:4444
__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
REISERFS warning (device loop3): reiserfs-15100 reiserfs_get_unused_objectid: no more object ids


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[syzbot]

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