loop1: detected capacity change from 0 to 512
EXT4-fs: Ignoring removed oldalloc option
EXT4-fs (loop1): mounted filesystem without journal. Quota mode: writeback.
EXT4-fs (loop1): re-mounted. Quota mode: writeback.
EXT4-fs (loop1): re-mounted. Quota mode: writeback.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.542/6050 is trying to acquire lock:
ffff8880758c47a8 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_commit+0x5a/0x410 fs/quota/dquot.c:535

but task is already holding lock:
ffff8880742e3eb8 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x914/0x1a90 fs/ext4/inode.c:674

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ei->i_data_sem/2){++++}-{3:3}:
       down_write+0x36/0x60 kernel/locking/rwsem.c:1573
       ext4_map_blocks+0x914/0x1a90 fs/ext4/inode.c:674
       ext4_getblk+0x1c5/0x720 fs/ext4/inode.c:892
       ext4_bread+0x26/0x170 fs/ext4/inode.c:948
       ext4_quota_write+0x237/0x580 fs/ext4/super.c:7228
       write_blk fs/quota/quota_tree.c:70 [inline]
       find_free_dqentry+0x68c/0xc30 fs/quota/quota_tree.c:318
       do_insert_tree+0x717/0x1060 fs/quota/quota_tree.c:400
       do_insert_tree+0x9b8/0x1060 fs/quota/quota_tree.c:402
       do_insert_tree+0x9b8/0x1060 fs/quota/quota_tree.c:402
       do_insert_tree+0x9b8/0x1060 fs/quota/quota_tree.c:402
       dq_insert_tree fs/quota/quota_tree.c:432 [inline]
       qtree_write_dquot+0x49b/0x5d0 fs/quota/quota_tree.c:451
       v2_write_dquot+0x108/0x190 fs/quota/quota_v2.c:361
       dquot_acquire+0x2d5/0x520 fs/quota/dquot.c:500
       ext4_acquire_dquot+0x2e3/0x4a0 fs/ext4/super.c:6837
       dqget+0x713/0xbb0 fs/quota/dquot.c:1013
       __dquot_initialize+0x324/0xd00 fs/quota/dquot.c:1542
       ext4_rename fs/ext4/namei.c:3868 [inline]
       ext4_rename2+0x6c1/0x3180 fs/ext4/namei.c:4258
       vfs_rename+0xd57/0x10f0 fs/namei.c:4925
       do_renameat2+0x8ac/0xc80 fs/namei.c:5078
       __do_sys_renameat2 fs/namei.c:5111 [inline]
       __se_sys_renameat2 fs/namei.c:5108 [inline]
       __x64_sys_renameat2+0xce/0xe0 fs/namei.c:5108
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       v2_read_dquot+0x4a/0x110 fs/quota/quota_v2.c:335
       dquot_acquire+0x152/0x520 fs/quota/dquot.c:491
       ext4_acquire_dquot+0x2e3/0x4a0 fs/ext4/super.c:6837
       dqget+0x713/0xbb0 fs/quota/dquot.c:1013
       __dquot_initialize+0x324/0xd00 fs/quota/dquot.c:1542
       ext4_file_open+0x2da/0x6f0 fs/ext4/file.c:869
       do_dentry_open+0x7dd/0x10b0 fs/open.c:882
       do_open fs/namei.c:3677 [inline]
       path_openat+0x2674/0x2f10 fs/namei.c:3834
       do_filp_open+0x1ee/0x420 fs/namei.c:3861
       do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
       do_sys_open fs/open.c:1336 [inline]
       __do_sys_open fs/open.c:1344 [inline]
       __se_sys_open fs/open.c:1340 [inline]
       __x64_sys_open+0x11b/0x140 fs/open.c:1340
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&dquot->dq_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3095 [inline]
       check_prevs_add kernel/locking/lockdep.c:3214 [inline]
       validate_chain kernel/locking/lockdep.c:3830 [inline]
       __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747
       dquot_commit+0x5a/0x410 fs/quota/dquot.c:535
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6817
       mark_dquot_dirty fs/quota/dquot.c:400 [inline]
       mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:440
       __dquot_alloc_space+0x5f6/0xe50 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+0xf55/0x44d0 fs/ext4/mballoc.c:5740
       ext4_alloc_branch fs/ext4/indirect.c:340 [inline]
       ext4_ind_map_blocks+0xee5/0x22d0 fs/ext4/indirect.c:635
       ext4_map_blocks+0x980/0x1a90 fs/ext4/inode.c:683
       ext4_getblk+0x1c5/0x720 fs/ext4/inode.c:892
       ext4_bread+0x26/0x170 fs/ext4/inode.c:948
       ext4_append+0x2bb/0x560 fs/ext4/namei.c:83
       ext4_init_new_dir+0x2b8/0x550 fs/ext4/namei.c:3030
       ext4_mkdir+0x4c3/0xc90 fs/ext4/namei.c:3076
       vfs_mkdir+0x386/0x570 fs/namei.c:4157
       do_mkdirat+0x1d8/0x440 fs/namei.c:4182
       __do_sys_mkdirat fs/namei.c:4197 [inline]
       __se_sys_mkdirat fs/namei.c:4195 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4195
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

4 locks held by syz.1.542/6050:
 #0: ffff888027b66460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402
 #1: ffff888075a9e850 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:799 [inline]
 #1: ffff888075a9e850 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3927
 #2: ffff8880742e3eb8 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x914/0x1a90 fs/ext4/inode.c:674
 #3: ffffffff8cc75368 (dquot_srcu){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #3: ffffffff8cc75368 (dquot_srcu){....}-{0:0}, at: srcu_read_lock include/linux/srcu.h:165 [inline]
 #3: ffffffff8cc75368 (dquot_srcu){....}-{0:0}, at: __dquot_alloc_space+0x16e/0xe50 fs/quota/dquot.c:1741

stack backtrace:
CPU: 0 PID: 6050 Comm: syz.1.542 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3095 [inline]
 check_prevs_add kernel/locking/lockdep.c:3214 [inline]
 validate_chain kernel/locking/lockdep.c:3830 [inline]
 __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747
 dquot_commit+0x5a/0x410 fs/quota/dquot.c:535
 ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6817
 mark_dquot_dirty fs/quota/dquot.c:400 [inline]
 mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:440
 __dquot_alloc_space+0x5f6/0xe50 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+0xf55/0x44d0 fs/ext4/mballoc.c:5740
 ext4_alloc_branch fs/ext4/indirect.c:340 [inline]
 ext4_ind_map_blocks+0xee5/0x22d0 fs/ext4/indirect.c:635
 ext4_map_blocks+0x980/0x1a90 fs/ext4/inode.c:683
 ext4_getblk+0x1c5/0x720 fs/ext4/inode.c:892
 ext4_bread+0x26/0x170 fs/ext4/inode.c:948
 ext4_append+0x2bb/0x560 fs/ext4/namei.c:83
 ext4_init_new_dir+0x2b8/0x550 fs/ext4/namei.c:3030
 ext4_mkdir+0x4c3/0xc90 fs/ext4/namei.c:3076
 vfs_mkdir+0x386/0x570 fs/namei.c:4157
 do_mkdirat+0x1d8/0x440 fs/namei.c:4182
 __do_sys_mkdirat fs/namei.c:4197 [inline]
 __se_sys_mkdirat fs/namei.c:4195 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4195
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f031039cfc7
Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0311306e58 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f0311306ee0 RCX: 00007f031039cfc7
RDX: 00000000000001ff RSI: 0000200000000440 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000200000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000440
R13: 00007f0311306ea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>