====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.5.632/6867 is trying to acquire lock: ffff0000f7270288 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x720/0x160c fs/ext4/inode.c:674 but task is already holding lock: ffff0000dc682208 (&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:6837 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_process_orphan+0x5c/0x2c0 fs/ext4/orphan.c:327 ext4_orphan_cleanup+0xabc/0x1204 fs/ext4/orphan.c:472 __ext4_fill_super fs/ext4/super.c:5574 [inline] ext4_fill_super+0x5afc/0x63bc fs/ext4/super.c:5693 get_tree_bdev+0x35c/0x54c fs/super.c:1377 ext4_get_tree+0x28/0x38 fs/ext4/super.c:5723 vfs_get_tree+0x90/0x278 fs/super.c:1584 do_new_mount+0x228/0x804 fs/namespace.c:3078 path_mount+0x5ac/0xe6c fs/namespace.c:3408 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount fs/namespace.c:3606 [inline] __arm64_sys_mount+0x4a0/0x5a0 fs/namespace.c:3606 __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:585 -> #1 (&dquot->dq_lock){+.+.}-{3:3}: __mutex_lock_common+0x1a0/0x1f3c 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:6817 ext4_mark_dquot_dirty+0xe8/0x150 fs/ext4/super.c:6894 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:5740 ext4_ext_map_blocks+0x1330/0x563c fs/ext4/extents.c:4361 ext4_map_blocks+0x7b0/0x160c fs/ext4/inode.c:681 _ext4_get_block+0x198/0x4dc fs/ext4/inode.c:824 ext4_get_block_unwritten+0x3c/0x110 fs/ext4/inode.c:857 __block_write_begin_int+0x3d8/0x13c0 fs/buffer.c:1991 __block_write_begin fs/buffer.c:2041 [inline] block_page_mkwrite+0x290/0x33c fs/buffer.c:2510 ext4_page_mkwrite+0x364/0x10b0 fs/ext4/inode.c:6361 do_page_mkwrite+0x140/0x35c mm/memory.c:3009 wp_page_shared+0x14c/0x544 mm/memory.c:3358 do_wp_page+0xc88/0xed4 mm/memory.c:3508 handle_pte_fault mm/memory.c:5047 [inline] __handle_mm_fault mm/memory.c:5171 [inline] handle_mm_fault+0x1520/0x3018 mm/memory.c:5292 __do_page_fault arch/arm64/mm/fault.c:499 [inline] do_page_fault+0x310/0x99c arch/arm64/mm/fault.c:583 do_mem_abort+0x70/0x198 arch/arm64/mm/fault.c:804 el0_da+0x74/0x14c arch/arm64/kernel/entry-common.c:515 el0t_64_sync_handler+0x90/0xf0 arch/arm64/kernel/entry-common.c:658 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: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_write+0x5c/0x88 kernel/locking/rwsem.c:1573 ext4_map_blocks+0x720/0x160c fs/ext4/inode.c:674 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:7228 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+0x7b0/0xc68 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:6837 dqget+0x638/0xa98 fs/quota/dquot.c:1013 __dquot_initialize+0x280/0xb30 fs/quota/dquot.c:1542 dquot_initialize+0x24/0x34 fs/quota/dquot.c:1604 ext4_create+0x9c/0x410 fs/ext4/namei.c:2878 lookup_open fs/namei.c:3533 [inline] open_last_lookups fs/namei.c:3601 [inline] path_openat+0xda8/0x27a0 fs/namei.c:3831 do_filp_open+0x198/0x38c fs/namei.c:3861 do_sys_openat2+0x134/0x3fc fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x11c/0x150 fs/open.c:1347 __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: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.5.632/6867: #0: ffff0000dc682460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:402 #1: ffff0000f7275440 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock include/linux/fs.h:764 [inline] #1: ffff0000f7275440 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: open_last_lookups fs/namei.c:3598 [inline] #1: ffff0000f7275440 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: path_openat+0x5dc/0x27a0 fs/namei.c:3831 #2: ffff0000f72b87a8 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_acquire+0x60/0x4b8 fs/quota/dquot.c:488 #3: ffff0000dc682208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_write_dquot+0x114/0x180 fs/quota/quota_v2.c:357 stack backtrace: CPU: 0 PID: 6867 Comm: syz.5.632 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_write+0x5c/0x88 kernel/locking/rwsem.c:1573 ext4_map_blocks+0x720/0x160c fs/ext4/inode.c:674 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:7228 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+0x7b0/0xc68 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:6837 dqget+0x638/0xa98 fs/quota/dquot.c:1013 __dquot_initialize+0x280/0xb30 fs/quota/dquot.c:1542 dquot_initialize+0x24/0x34 fs/quota/dquot.c:1604 ext4_create+0x9c/0x410 fs/ext4/namei.c:2878 lookup_open fs/namei.c:3533 [inline] open_last_lookups fs/namei.c:3601 [inline] path_openat+0xda8/0x27a0 fs/namei.c:3831 do_filp_open+0x198/0x38c fs/namei.c:3861 do_sys_openat2+0x134/0x3fc fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x11c/0x150 fs/open.c:1347 __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:585