syzbot

======================================================
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