======================================================
WARNING: possible circular locking dependency detected
6.1.141-syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1082/7017 is trying to acquire lock:
ffff0000f5a570e0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x278/0x1770 fs/ext4/inode.c:604

but task is already holding lock:
ffff0000ddc70208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_write_dquot+0x114/0x180 fs/quota/quota_v2.c:357

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       down_read+0x64/0x304 kernel/locking/rwsem.c:1520
       v2_read_dquot+0x4c/0x118 fs/quota/quota_v2.c:335
       dquot_acquire+0x120/0x4e0 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x270/0x428 fs/ext4/super.c:6810
       dqget+0x654/0xccc fs/quota/dquot.c:988
       __dquot_initialize+0x2d4/0xa80 fs/quota/dquot.c:1517
       dquot_initialize+0x24/0x34 fs/quota/dquot.c:1579
       ext4_mkdir+0x148/0xa2c fs/ext4/namei.c:3059
       vfs_mkdir+0x314/0x4d4 fs/namei.c:4106
       do_mkdirat+0x1b4/0x3e0 fs/namei.c:4131
       __do_sys_mkdirat fs/namei.c:4146 [inline]
       __se_sys_mkdirat fs/namei.c:4144 [inline]
       __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4144
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 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:585

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x190/0x1f38 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
       dquot_commit+0x50/0x1c4 fs/quota/dquot.c:507
       ext4_write_dquot+0x1b4/0x31c fs/ext4/super.c:6790
       ext4_mark_dquot_dirty+0xe8/0x140 fs/ext4/super.c:6867
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0x108/0x424 fs/quota/dquot.c:412
       __dquot_alloc_space+0x560/0xce8 fs/quota/dquot.c:1752
       dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline]
       dquot_alloc_space include/linux/quotaops.h:313 [inline]
       dquot_alloc_block include/linux/quotaops.h:337 [inline]
       ext4_mb_new_blocks+0xd30/0x435c fs/ext4/mballoc.c:5727
       ext4_ext_map_blocks+0x1018/0x559c fs/ext4/extents.c:4339
       ext4_map_blocks+0x860/0x1770 fs/ext4/inode.c:679
       ext4_getblk+0x170/0x654 fs/ext4/inode.c:890
       ext4_bread+0x3c/0x1b0 fs/ext4/inode.c:946
       ext4_append+0x238/0x474 fs/ext4/namei.c:83
       ext4_init_new_dir+0x264/0x4f4 fs/ext4/namei.c:3030
       ext4_mkdir+0x3c0/0xa2c fs/ext4/namei.c:3076
       vfs_mkdir+0x314/0x4d4 fs/namei.c:4106
       ovl_do_mkdir fs/overlayfs/overlayfs.h:186 [inline]
       ovl_mkdir_real+0xa8/0x200 fs/overlayfs/dir.c:146
       ovl_workdir_create+0x2a4/0x634 fs/overlayfs/super.c:799
       ovl_get_indexdir+0x1cc/0x4f8 fs/overlayfs/super.c:1571
       ovl_fill_super+0x15ec/0x2294 fs/overlayfs/super.c:2120
       mount_nodev+0x68/0x104 fs/super.c:1489
       ovl_mount+0x3c/0x50 fs/overlayfs/super.c:2186
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:632
       vfs_get_tree+0x90/0x274 fs/super.c:1573
       do_new_mount+0x228/0x810 fs/namespace.c:3054
       path_mount+0x5b4/0xe78 fs/namespace.c:3384
       do_mount fs/namespace.c:3397 [inline]
       __do_sys_mount fs/namespace.c:3605 [inline]
       __se_sys_mount fs/namespace.c:3582 [inline]
       __arm64_sys_mount+0x49c/0x584 fs/namespace.c:3582
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 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:585

-> #0 (&ei->i_data_sem/2){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x293c/0x6544 kernel/locking/lockdep.c:5049
       lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
       down_read+0x64/0x304 kernel/locking/rwsem.c:1520
       ext4_map_blocks+0x278/0x1770 fs/ext4/inode.c:604
       ext4_getblk+0x170/0x654 fs/ext4/inode.c:890
       ext4_bread+0x3c/0x1b0 fs/ext4/inode.c:946
       ext4_quota_write+0x228/0x51c fs/ext4/super.c:7201
       write_blk fs/quota/quota_tree.c:70 [inline]
       get_free_dqblk+0x284/0x574 fs/quota/quota_tree.c:136
       do_insert_tree+0x1c4/0xc38 fs/quota/quota_tree.c:347
       do_insert_tree+0x794/0xc38 fs/quota/quota_tree.c:402
       do_insert_tree+0x794/0xc38 fs/quota/quota_tree.c:402
       do_insert_tree+0x794/0xc38 fs/quota/quota_tree.c:402
       dq_insert_tree fs/quota/quota_tree.c:432 [inline]
       qtree_write_dquot+0x3bc/0x4c8 fs/quota/quota_tree.c:451
       v2_write_dquot+0xf0/0x180 fs/quota/quota_v2.c:361
       dquot_acquire+0x2a8/0x4e0 fs/quota/dquot.c:472
       ext4_acquire_dquot+0x270/0x428 fs/ext4/super.c:6810
       dqget+0x654/0xccc fs/quota/dquot.c:988
       __dquot_initialize+0x2d4/0xa80 fs/quota/dquot.c:1517
       dquot_initialize+0x24/0x34 fs/quota/dquot.c:1579
       ext4_xattr_set+0xb8/0x2b4 fs/ext4/xattr.c:2499
       ext4_xattr_security_set+0x4c/0x64 fs/ext4/xattr_security.c:31
       __vfs_setxattr+0x388/0x3a4 fs/xattr.c:182
       __vfs_setxattr_noperm+0x120/0x564 fs/xattr.c:216
       __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:277
       vfs_setxattr+0x158/0x2ac fs/xattr.c:309
       do_setxattr fs/xattr.c:594 [inline]
       setxattr+0x228/0x28c fs/xattr.c:617
       path_setxattr+0x12c/0x25c fs/xattr.c:636
       __do_sys_setxattr fs/xattr.c:652 [inline]
       __se_sys_setxattr fs/xattr.c:648 [inline]
       __arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:648
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 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:585

other info that might help us debug this:

Chain exists of:
  &ei->i_data_sem/2 --> &dquot->dq_lock --> &s->s_dquot.dqio_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&s->s_dquot.dqio_sem);
                               lock(&dquot->dq_lock);
                               lock(&s->s_dquot.dqio_sem);
  lock(&ei->i_data_sem/2);

 *** DEADLOCK ***

4 locks held by syz.2.1082/7017:
 #0: ffff0000ddc70460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393
 #1: ffff0000f5a52c20 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff0000f5a52c20 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: vfs_setxattr+0x138/0x2ac fs/xattr.c:308
 #2: ffff0000f5a18428 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_acquire+0x60/0x4e0 fs/quota/dquot.c:460
 #3: ffff0000ddc70208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_write_dquot+0x114/0x180 fs/quota/quota_v2.c:357

stack backtrace:
CPU: 1 PID: 7017 Comm: syz.2.1082 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2048
 check_noncircular+0x240/0x2d4 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x293c/0x6544 kernel/locking/lockdep.c:5049
 lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
 down_read+0x64/0x304 kernel/locking/rwsem.c:1520
 ext4_map_blocks+0x278/0x1770 fs/ext4/inode.c:604
 ext4_getblk+0x170/0x654 fs/ext4/inode.c:890
 ext4_bread+0x3c/0x1b0 fs/ext4/inode.c:946
 ext4_quota_write+0x228/0x51c fs/ext4/super.c:7201
 write_blk fs/quota/quota_tree.c:70 [inline]
 get_free_dqblk+0x284/0x574 fs/quota/quota_tree.c:136
 do_insert_tree+0x1c4/0xc38 fs/quota/quota_tree.c:347
 do_insert_tree+0x794/0xc38 fs/quota/quota_tree.c:402
 do_insert_tree+0x794/0xc38 fs/quota/quota_tree.c:402
 do_insert_tree+0x794/0xc38 fs/quota/quota_tree.c:402
 dq_insert_tree fs/quota/quota_tree.c:432 [inline]
 qtree_write_dquot+0x3bc/0x4c8 fs/quota/quota_tree.c:451
 v2_write_dquot+0xf0/0x180 fs/quota/quota_v2.c:361
 dquot_acquire+0x2a8/0x4e0 fs/quota/dquot.c:472
 ext4_acquire_dquot+0x270/0x428 fs/ext4/super.c:6810
 dqget+0x654/0xccc fs/quota/dquot.c:988
 __dquot_initialize+0x2d4/0xa80 fs/quota/dquot.c:1517
 dquot_initialize+0x24/0x34 fs/quota/dquot.c:1579
 ext4_xattr_set+0xb8/0x2b4 fs/ext4/xattr.c:2499
 ext4_xattr_security_set+0x4c/0x64 fs/ext4/xattr_security.c:31
 __vfs_setxattr+0x388/0x3a4 fs/xattr.c:182
 __vfs_setxattr_noperm+0x120/0x564 fs/xattr.c:216
 __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:277
 vfs_setxattr+0x158/0x2ac fs/xattr.c:309
 do_setxattr fs/xattr.c:594 [inline]
 setxattr+0x228/0x28c fs/xattr.c:617
 path_setxattr+0x12c/0x25c fs/xattr.c:636
 __do_sys_setxattr fs/xattr.c:652 [inline]
 __se_sys_setxattr fs/xattr.c:648 [inline]
 __arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:648
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 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:585