syzbot

loop0: detected capacity change from 0 to 512
ext4 filesystem being mounted at /79/file0 supports timestamps until 2038-01-19 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
5.15.188-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.95/4511 is trying to acquire lock:
ffff88805ce16ce8 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_commit+0x5a/0x410 fs/quota/dquot.c:507

but task is already holding lock:
ffff88805cedaa58 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x8b2/0x1b30 fs/ext4/inode.c:666

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_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       ext4_map_blocks+0x32f/0x1b30 fs/ext4/inode.c:598
       ext4_getblk+0x16d/0x630 fs/ext4/inode.c:870
       ext4_bread+0x26/0x180 fs/ext4/inode.c:923
       ext4_quota_read+0x1b3/0x3a0 fs/ext4/super.c:6548
       read_blk fs/quota/quota_tree.c:55 [inline]
       find_tree_dqentry+0x188/0xb30 fs/quota/quota_tree.c:617
       find_tree_dqentry+0x3eb/0xb30 fs/quota/quota_tree.c:635
       find_tree_dqentry+0x3eb/0xb30 fs/quota/quota_tree.c:635
       find_tree_dqentry+0x3eb/0xb30 fs/quota/quota_tree.c:635
       find_dqentry fs/quota/quota_tree.c:647 [inline]
       qtree_read_dquot+0x13c/0x680 fs/quota/quota_tree.c:667
       v2_read_dquot+0xc0/0x110 fs/quota/quota_v2.c:333
       dquot_acquire+0x152/0x520 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6203
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x328/0xcb0 fs/quota/dquot.c:1517
       ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xaa9/0x12e0 fs/ext4/orphan.c:474
       ext4_fill_super+0x9288/0x9a00 fs/ext4/super.c:4973
       mount_bdev+0x287/0x3c0 fs/super.c:1400
       legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
       vfs_get_tree+0x88/0x270 fs/super.c:1530
       do_new_mount+0x24a/0xa40 fs/namespace.c:3014
       do_mount fs/namespace.c:3357 [inline]
       __do_sys_mount fs/namespace.c:3565 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3542
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       v2_read_dquot+0x4a/0x110 fs/quota/quota_v2.c:332
       dquot_acquire+0x152/0x520 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6203
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x328/0xcb0 fs/quota/dquot.c:1517
       ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xaa9/0x12e0 fs/ext4/orphan.c:474
       ext4_fill_super+0x9288/0x9a00 fs/ext4/super.c:4973
       mount_bdev+0x287/0x3c0 fs/super.c:1400
       legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
       vfs_get_tree+0x88/0x270 fs/super.c:1530
       do_new_mount+0x24a/0xa40 fs/namespace.c:3014
       do_mount fs/namespace.c:3357 [inline]
       __do_sys_mount fs/namespace.c:3565 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3542
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&dquot->dq_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6183
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
       __dquot_alloc_space+0x5d0/0xe20 fs/quota/dquot.c:1752
       dquot_alloc_space_nodirty include/linux/quotaops.h:297 [inline]
       dquot_alloc_space include/linux/quotaops.h:310 [inline]
       dquot_alloc_block include/linux/quotaops.h:334 [inline]
       ext4_mb_new_blocks+0xf68/0x4940 fs/ext4/mballoc.c:5739
       ext4_ext_map_blocks+0x146f/0x64e0 fs/ext4/extents.c:4341
       ext4_map_blocks+0x981/0x1b30 fs/ext4/inode.c:673
       ext4_getblk+0x16d/0x630 fs/ext4/inode.c:870
       ext4_bread+0x26/0x180 fs/ext4/inode.c:923
       ext4_append+0x2c3/0x560 fs/ext4/namei.c:83
       ext4_init_new_dir+0x2a2/0x940 fs/ext4/namei.c:3030
       ext4_mkdir+0x47d/0xc50 fs/ext4/namei.c:3076
       vfs_mkdir+0x387/0x570 fs/namei.c:4065
       do_mkdirat+0x1d7/0x5a0 fs/namei.c:4090
       __do_sys_mkdir fs/namei.c:4110 [inline]
       __se_sys_mkdir fs/namei.c:4108 [inline]
       __x64_sys_mkdir+0x6a/0x80 fs/namei.c:4108
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.0.95/4511:
 #0: ffff88801d4ea460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:377
 #1: ffff88805cccd3b0 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
 #1: ffff88805cccd3b0 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: filename_create+0x1f2/0x450 fs/namei.c:3835
 #2: ffff88805cedaa58 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x8b2/0x1b30 fs/ext4/inode.c:666
 #3: ffffffff8c240158 (dquot_srcu){....}-{0:0}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311

stack backtrace:
CPU: 1 PID: 4511 Comm: syz.0.95 Not tainted 5.15.188-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
 ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6183
 mark_dquot_dirty fs/quota/dquot.c:372 [inline]
 mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
 __dquot_alloc_space+0x5d0/0xe20 fs/quota/dquot.c:1752
 dquot_alloc_space_nodirty include/linux/quotaops.h:297 [inline]
 dquot_alloc_space include/linux/quotaops.h:310 [inline]
 dquot_alloc_block include/linux/quotaops.h:334 [inline]
 ext4_mb_new_blocks+0xf68/0x4940 fs/ext4/mballoc.c:5739
 ext4_ext_map_blocks+0x146f/0x64e0 fs/ext4/extents.c:4341
 ext4_map_blocks+0x981/0x1b30 fs/ext4/inode.c:673
 ext4_getblk+0x16d/0x630 fs/ext4/inode.c:870
 ext4_bread+0x26/0x180 fs/ext4/inode.c:923
 ext4_append+0x2c3/0x560 fs/ext4/namei.c:83
 ext4_init_new_dir+0x2a2/0x940 fs/ext4/namei.c:3030
 ext4_mkdir+0x47d/0xc50 fs/ext4/namei.c:3076
 vfs_mkdir+0x387/0x570 fs/namei.c:4065
 do_mkdirat+0x1d7/0x5a0 fs/namei.c:4090
 __do_sys_mkdir fs/namei.c:4110 [inline]
 __se_sys_mkdir fs/namei.c:4108 [inline]
 __x64_sys_mkdir+0x6a/0x80 fs/namei.c:4108
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fdd61db2929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd101d5468 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007fdd61fd9fa0 RCX: 00007fdd61db2929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000300
RBP: 00007fdd61e34b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdd61fd9fa0 R14: 00007fdd61fd9fa0 R15: 0000000000000002
 </TASK>