====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor/4339 is trying to acquire lock: ffff0000f6298c90 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x270/0x160c fs/ext4/inode.c:606 but task is already holding lock: ffff0000d2746208 (&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+0x108/0x4b8 fs/quota/dquot.c:491 ext4_acquire_dquot+0x270/0x420 fs/ext4/super.c:6844 dqget+0x638/0xa98 fs/quota/dquot.c:1013 __dquot_initialize+0x2e4/0xb30 fs/quota/dquot.c:1542 dquot_initialize+0x24/0x34 fs/quota/dquot.c:1604 ext4_mkdir+0x154/0xa28 fs/ext4/namei.c:3061 vfs_mkdir+0x314/0x4d8 fs/namei.c:4161 do_mkdirat+0x1b8/0x3ec fs/namei.c:4186 __do_sys_mkdirat fs/namei.c:4201 [inline] __se_sys_mkdirat fs/namei.c:4199 [inline] __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4199 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:589 -> #1 (&dquot->dq_lock){+.+.}-{3:3}: __mutex_lock_common+0x1a0/0x1f88 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+0x54/0x1c8 fs/quota/dquot.c:535 ext4_write_dquot+0x1b4/0x320 fs/ext4/super.c:6824 ext4_mark_dquot_dirty+0xe8/0x150 fs/ext4/super.c:6901 mark_dquot_dirty fs/quota/dquot.c:400 [inline] mark_all_dquot_dirty+0x108/0x424 fs/quota/dquot.c:440 __dquot_alloc_space+0x564/0xcfc fs/quota/dquot.c:1777 dquot_alloc_space_nodirty include/linux/quotaops.h:293 [inline] dquot_alloc_space include/linux/quotaops.h:306 [inline] dquot_alloc_block include/linux/quotaops.h:330 [inline] ext4_mb_new_blocks+0xd40/0x4244 fs/ext4/mballoc.c:5755 ext4_ext_map_blocks+0x12bc/0x5680 fs/ext4/extents.c:4369 ext4_map_blocks+0x7b0/0x160c fs/ext4/inode.c:681 ext4_getblk+0x178/0x680 fs/ext4/inode.c:892 ext4_bread+0x3c/0x1a8 fs/ext4/inode.c:948 ext4_append+0x23c/0x488 fs/ext4/namei.c:83 ext4_init_new_dir+0x270/0x4f0 fs/ext4/namei.c:3032 ext4_mkdir+0x3b8/0xa28 fs/ext4/namei.c:3078 vfs_mkdir+0x314/0x4d8 fs/namei.c:4161 ovl_do_mkdir fs/overlayfs/overlayfs.h:186 [inline] ovl_mkdir_real+0xa8/0x204 fs/overlayfs/dir.c:146 ovl_workdir_create+0x2c8/0x66c fs/overlayfs/super.c:799 ovl_get_indexdir+0x1c8/0x4e0 fs/overlayfs/super.c:1571 ovl_fill_super+0x2b94/0x3938 fs/overlayfs/super.c:2120 mount_nodev+0x68/0x108 fs/super.c:1500 ovl_mount+0x3c/0x50 fs/overlayfs/super.c:2186 legacy_get_tree+0xd8/0x174 fs/fs_context.c:632 vfs_get_tree+0x90/0x278 fs/super.c:1584 do_new_mount+0x228/0x818 fs/namespace.c:3104 path_mount+0x5ac/0xe6c fs/namespace.c:3462 do_mount fs/namespace.c:3475 [inline] __do_sys_mount fs/namespace.c:3683 [inline] __se_sys_mount fs/namespace.c:3660 [inline] __arm64_sys_mount+0x4a0/0x5a0 fs/namespace.c:3660 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:589 -> #0 (&ei->i_data_sem/2){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3504/0x7280 kernel/locking/lockdep.c:5171 lock_acquire+0x210/0x63c kernel/locking/lockdep.c:5790 down_read+0x64/0x300 kernel/locking/rwsem.c:1520 ext4_map_blocks+0x270/0x160c fs/ext4/inode.c:606 ext4_getblk+0x178/0x680 fs/ext4/inode.c:892 ext4_bread+0x3c/0x1a8 fs/ext4/inode.c:948 ext4_quota_write+0x200/0x544 fs/ext4/super.c:7223 write_blk fs/quota/quota_tree.c:70 [inline] get_free_dqblk+0x27c/0x570 fs/quota/quota_tree.c:136 do_insert_tree+0x1ec/0xc68 fs/quota/quota_tree.c:347 do_insert_tree+0x7dc/0xc68 fs/quota/quota_tree.c:402 do_insert_tree+0x7dc/0xc68 fs/quota/quota_tree.c:402 do_insert_tree+0x7dc/0xc68 fs/quota/quota_tree.c:402 dq_insert_tree fs/quota/quota_tree.c:432 [inline] qtree_write_dquot+0x3d4/0x4e4 fs/quota/quota_tree.c:451 v2_write_dquot+0xf0/0x180 fs/quota/quota_v2.c:361 dquot_acquire+0x280/0x4b8 fs/quota/dquot.c:500 ext4_acquire_dquot+0x270/0x420 fs/ext4/super.c:6844 dqget+0x638/0xa98 fs/quota/dquot.c:1013 __dquot_initialize+0x2e4/0xb30 fs/quota/dquot.c:1542 dquot_initialize+0x24/0x34 fs/quota/dquot.c:1604 ext4_unlink+0x18c/0x714 fs/ext4/namei.c:3368 vfs_unlink+0x2e0/0x4f4 fs/namei.c:4377 do_unlinkat+0x318/0x504 fs/namei.c:4445 __do_sys_unlinkat fs/namei.c:4488 [inline] __se_sys_unlinkat fs/namei.c:4481 [inline] __arm64_sys_unlinkat+0xe0/0xfc fs/namei.c:4481 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:589 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); rlock(&ei->i_data_sem/2); *** DEADLOCK *** 5 locks held by syz-executor/4339: #0: ffff0000d2746460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:402 #1: ffff0000f629e850 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:799 [inline] #1: ffff0000f629e850 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0x184/0x504 fs/namei.c:4428 #2: ffff0000f62b0e08 (&sb->s_type->i_mutex_key#10){++++}-{3:3}, at: inode_lock include/linux/fs.h:764 [inline] #2: ffff0000f62b0e08 (&sb->s_type->i_mutex_key#10){++++}-{3:3}, at: vfs_unlink+0xd0/0x4f4 fs/namei.c:4366 #3: ffff0000f7cee7a8 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_acquire+0x60/0x4b8 fs/quota/dquot.c:488 #4: ffff0000d2746208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_write_dquot+0x114/0x180 fs/quota/quota_v2.c:357 stack backtrace: CPU: 0 PID: 4339 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026 Call trace: dump_backtrace+0x1c4/0x1f0 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:2088 check_noncircular+0x290/0x370 kernel/locking/lockdep.c:2215 check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3504/0x7280 kernel/locking/lockdep.c:5171 lock_acquire+0x210/0x63c kernel/locking/lockdep.c:5790 down_read+0x64/0x300 kernel/locking/rwsem.c:1520 ext4_map_blocks+0x270/0x160c fs/ext4/inode.c:606 ext4_getblk+0x178/0x680 fs/ext4/inode.c:892 ext4_bread+0x3c/0x1a8 fs/ext4/inode.c:948 ext4_quota_write+0x200/0x544 fs/ext4/super.c:7223 write_blk fs/quota/quota_tree.c:70 [inline] get_free_dqblk+0x27c/0x570 fs/quota/quota_tree.c:136 do_insert_tree+0x1ec/0xc68 fs/quota/quota_tree.c:347 do_insert_tree+0x7dc/0xc68 fs/quota/quota_tree.c:402 do_insert_tree+0x7dc/0xc68 fs/quota/quota_tree.c:402 do_insert_tree+0x7dc/0xc68 fs/quota/quota_tree.c:402 dq_insert_tree fs/quota/quota_tree.c:432 [inline] qtree_write_dquot+0x3d4/0x4e4 fs/quota/quota_tree.c:451 v2_write_dquot+0xf0/0x180 fs/quota/quota_v2.c:361 dquot_acquire+0x280/0x4b8 fs/quota/dquot.c:500 ext4_acquire_dquot+0x270/0x420 fs/ext4/super.c:6844 dqget+0x638/0xa98 fs/quota/dquot.c:1013 __dquot_initialize+0x2e4/0xb30 fs/quota/dquot.c:1542 dquot_initialize+0x24/0x34 fs/quota/dquot.c:1604 ext4_unlink+0x18c/0x714 fs/ext4/namei.c:3368 vfs_unlink+0x2e0/0x4f4 fs/namei.c:4377 do_unlinkat+0x318/0x504 fs/namei.c:4445 __do_sys_unlinkat fs/namei.c:4488 [inline] __se_sys_unlinkat fs/namei.c:4481 [inline] __arm64_sys_unlinkat+0xe0/0xfc fs/namei.c:4481 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:589 EXT4-fs (loop3): unmounting filesystem.