====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.184/5167 is trying to acquire lock: ffff0000f50a3eb8 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x278/0x1778 fs/ext4/inode.c:606 but task is already holding lock: ffff0000dcf4c208 (&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+0x64/0x300 kernel/locking/rwsem.c:1520 v2_read_dquot+0x4c/0x118 fs/quota/quota_v2.c:335 dquot_acquire+0x120/0x4d8 fs/quota/dquot.c:463 ext4_acquire_dquot+0x270/0x428 fs/ext4/super.c:6837 dqget+0x654/0xcc4 fs/quota/dquot.c:988 __dquot_initialize+0x2fc/0xacc fs/quota/dquot.c:1517 dquot_initialize+0x24/0x34 fs/quota/dquot.c:1579 ext4_mkdir+0x150/0xa1c fs/ext4/namei.c:3059 vfs_mkdir+0x314/0x4d4 fs/namei.c:4114 do_mkdirat+0x1b8/0x3ec fs/namei.c:4139 __do_sys_mkdirat fs/namei.c:4154 [inline] __se_sys_mkdirat fs/namei.c:4152 [inline] __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4152 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x1fc/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 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+0x190/0x1f60 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:6817 ext4_mark_dquot_dirty+0xe8/0x140 fs/ext4/super.c:6894 mark_dquot_dirty fs/quota/dquot.c:372 [inline] mark_all_dquot_dirty+0x108/0x424 fs/quota/dquot.c:412 __dquot_alloc_space+0x560/0xce0 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+0xd38/0x4254 fs/ext4/mballoc.c:5740 ext4_ext_map_blocks+0x1394/0x56f4 fs/ext4/extents.c:4346 ext4_map_blocks+0x860/0x1778 fs/ext4/inode.c:681 ext4_alloc_file_blocks+0x2ac/0x8ec fs/ext4/extents.c:4530 ext4_fallocate+0x784/0x1b54 fs/ext4/extents.c:4817 vfs_fallocate+0x4a4/0x5f4 fs/open.c:323 ioctl_preallocate+0x20c/0x2b4 fs/ioctl.c:290 file_ioctl fs/ioctl.c:-1 [inline] do_vfs_ioctl+0x1874/0x2100 fs/ioctl.c:849 __do_sys_ioctl fs/ioctl.c:868 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 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+0x2880/0x6800 kernel/locking/lockdep.c:5049 lock_acquire+0x20c/0x63c kernel/locking/lockdep.c:5662 down_read+0x64/0x300 kernel/locking/rwsem.c:1520 ext4_map_blocks+0x278/0x1778 fs/ext4/inode.c:606 ext4_getblk+0x178/0x664 fs/ext4/inode.c:892 ext4_bread+0x3c/0x1a8 fs/ext4/inode.c:948 ext4_quota_write+0x204/0x534 fs/ext4/super.c:7228 write_blk fs/quota/quota_tree.c:70 [inline] get_free_dqblk+0x284/0x574 fs/quota/quota_tree.c:136 do_insert_tree+0x1c4/0xc34 fs/quota/quota_tree.c:347 do_insert_tree+0x790/0xc34 fs/quota/quota_tree.c:402 dq_insert_tree fs/quota/quota_tree.c:432 [inline] qtree_write_dquot+0x3d4/0x4f0 fs/quota/quota_tree.c:451 v2_write_dquot+0xf0/0x180 fs/quota/quota_v2.c:361 dquot_acquire+0x2a8/0x4d8 fs/quota/dquot.c:472 ext4_acquire_dquot+0x270/0x428 fs/ext4/super.c:6837 dqget+0x654/0xcc4 fs/quota/dquot.c:988 dquot_transfer+0x314/0x708 fs/quota/dquot.c:2150 ext4_setattr+0x7d4/0x15f0 fs/ext4/inode.c:5527 notify_change+0xb0c/0xdcc fs/attr.c:499 chown_common+0x420/0x594 fs/open.c:736 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+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 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 *** 5 locks held by syz.1.184/5167: #0: ffff0000dcf4c460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:446 #1: ffff0000f50a6850 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline] #1: ffff0000f50a6850 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: chown_common+0x2b8/0x594 fs/open.c:726 #2: ffff0000f50a6518 (&ei->xattr_sem){++++}-{3:3}, at: ext4_setattr+0x7c4/0x15f0 fs/ext4/inode.c:5526 #3: ffff0000f5114428 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_acquire+0x60/0x4d8 fs/quota/dquot.c:460 #4: ffff0000dcf4c208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_write_dquot+0x114/0x180 fs/quota/quota_v2.c:357 stack backtrace: CPU: 0 PID: 5167 Comm: syz.1.184 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/26/2026 Call trace: dump_backtrace+0x1c0/0x1ec 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+0xf4/0x15c 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+0x264/0x2f8 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+0x2880/0x6800 kernel/locking/lockdep.c:5049 lock_acquire+0x20c/0x63c kernel/locking/lockdep.c:5662 down_read+0x64/0x300 kernel/locking/rwsem.c:1520 ext4_map_blocks+0x278/0x1778 fs/ext4/inode.c:606 ext4_getblk+0x178/0x664 fs/ext4/inode.c:892 ext4_bread+0x3c/0x1a8 fs/ext4/inode.c:948 ext4_quota_write+0x204/0x534 fs/ext4/super.c:7228 write_blk fs/quota/quota_tree.c:70 [inline] get_free_dqblk+0x284/0x574 fs/quota/quota_tree.c:136 do_insert_tree+0x1c4/0xc34 fs/quota/quota_tree.c:347 do_insert_tree+0x790/0xc34 fs/quota/quota_tree.c:402 dq_insert_tree fs/quota/quota_tree.c:432 [inline] qtree_write_dquot+0x3d4/0x4f0 fs/quota/quota_tree.c:451 v2_write_dquot+0xf0/0x180 fs/quota/quota_v2.c:361 dquot_acquire+0x2a8/0x4d8 fs/quota/dquot.c:472 ext4_acquire_dquot+0x270/0x428 fs/ext4/super.c:6837 dqget+0x654/0xcc4 fs/quota/dquot.c:988 dquot_transfer+0x314/0x708 fs/quota/dquot.c:2150 ext4_setattr+0x7d4/0x15f0 fs/ext4/inode.c:5527 notify_change+0xb0c/0xdcc fs/attr.c:499 chown_common+0x420/0x594 fs/open.c:736 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+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 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 Quota error (device loop1): write_blk: dquota write failed Quota error (device loop1): qtree_write_dquot: Error -28 occurred while creating quota EXT4-fs error (device loop1): ext4_acquire_dquot:6841: comm syz.1.184: Failed to acquire dquot type 0