[v5.15] possible deadlock in sys_quotactl_fd (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f7347f400572 Linux 5.15.180
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13069f54580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e6c84b0caba70e14
dashboard link: https://syzkaller.appspot.com/bug?extid=06a13d625b4c4931444b
compiler: Debian clang version 15.0.6, Debian LLD 15.0.6
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5ea7676abfeb/disk-f7347f40.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a6c1adba70a4/vmlinux-f7347f40.xz
kernel image: https://storage.googleapis.com/syzbot-assets/111bbc36e182/Image-f7347f40.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+06a13d...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.180-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.7/4113 is trying to acquire lock:
ffff0000d9e380e0 (&type->s_umount_key#52){+.+.}-{3:3}, at: __do_sys_quotactl_fd fs/quota/quota.c:996 [inline]
ffff0000d9e380e0 (&type->s_umount_key#52){+.+.}-{3:3}, at: __se_sys_quotactl_fd fs/quota/quota.c:971 [inline]
ffff0000d9e380e0 (&type->s_umount_key#52){+.+.}-{3:3}, at: __arm64_sys_quotactl_fd+0x2fc/0x4a4 fs/quota/quota.c:971

but task is already holding lock:
ffff0000d9e38460 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#14){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1811 [inline]
sb_start_write+0xf0/0x3ac include/linux/fs.h:1881
mnt_want_write_file+0x64/0x1e8 fs/namespace.c:421
reiserfs_ioctl+0x188/0x4b8 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&sbi->lock){+.+.}-{3:3}:
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_sync_fs+0xa0/0x150 fs/reiserfs/super.c:76
sync_filesystem+0xe8/0x218 fs/sync.c:56
generic_shutdown_super+0x70/0x2f0 fs/super.c:448
kill_block_super+0x70/0xdc fs/super.c:1427
reiserfs_kill_sb+0x134/0x14c fs/reiserfs/super.c:570
deactivate_locked_super+0xb8/0x13c fs/super.c:335
deactivate_super+0x108/0x128 fs/super.c:366
cleanup_mnt+0x3c0/0x474 fs/namespace.c:1143
__cleanup_mnt+0x20/0x30 fs/namespace.c:1150
task_work_run+0x130/0x1e4 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
do_notify_resume+0x262c/0x32b8 arch/arm64/kernel/signal.c:946
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&type->s_umount_key#52){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
down_write+0xbc/0x12c kernel/locking/rwsem.c:1551
__do_sys_quotactl_fd fs/quota/quota.c:996 [inline]
__se_sys_quotactl_fd fs/quota/quota.c:971 [inline]
__arm64_sys_quotactl_fd+0x2fc/0x4a4 fs/quota/quota.c:971
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
&type->s_umount_key#52 --> &sbi->lock --> sb_writers#14

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sb_writers#14);
lock(&sbi->lock);
lock(sb_writers#14);
lock(&type->s_umount_key#52);

*** DEADLOCK ***

1 lock held by syz.0.7/4113:
#0: ffff0000d9e38460 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

stack backtrace:
CPU: 1 PID: 4113 Comm: syz.0.7 Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__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:2011
check_noncircular+0x2cc/0x378 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 kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
down_write+0xbc/0x12c kernel/locking/rwsem.c:1551
__do_sys_quotactl_fd fs/quota/quota.c:996 [inline]
__se_sys_quotactl_fd fs/quota/quota.c:971 [inline]
__arm64_sys_quotactl_fd+0x2fc/0x4a4 fs/quota/quota.c:971
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584


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[syzbot]

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