syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.1595/11789 is trying to acquire lock:
ffff88804ee034b0 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_move_extents+0x325/0xb90 fs/ext4/move_extent.c:615

but task is already holding lock:
ffff88804ee00c90 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40 fs/ext4/move_extent.c:-1

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ei->i_data_sem/2){++++}-{3:3}:
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       ext4_map_blocks+0x316/0x1b60 fs/ext4/inode.c:604
       ext4_getblk+0x1ab/0x6d0 fs/ext4/inode.c:890
       ext4_bread+0x26/0x170 fs/ext4/inode.c:946
       ext4_quota_read+0x180/0x380 fs/ext4/super.c:7150
       read_blk fs/quota/quota_tree.c:61 [inline]
       find_tree_dqentry+0x1cd/0xf30 fs/quota/quota_tree.c:671
       find_tree_dqentry+0x6b0/0xf30 fs/quota/quota_tree.c:698
       find_tree_dqentry+0x6b0/0xf30 fs/quota/quota_tree.c:698
       find_tree_dqentry+0x6b0/0xf30 fs/quota/quota_tree.c:698
       find_dqentry fs/quota/quota_tree.c:716 [inline]
       qtree_read_dquot+0x558/0x7f0 fs/quota/quota_tree.c:736
       v2_read_dquot+0xc0/0x110 fs/quota/quota_v2.c:336
       dquot_acquire+0x152/0x520 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6805
       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:325
       ext4_orphan_cleanup+0xbd3/0x1400 fs/ext4/orphan.c:470
       __ext4_fill_super fs/ext4/super.c:5530 [inline]
       ext4_fill_super+0x7bdf/0x8150 fs/ext4/super.c:5661
       get_tree_bdev+0x3f1/0x610 fs/super.c:1366
       vfs_get_tree+0x88/0x270 fs/super.c:1573
       do_new_mount+0x24a/0xa40 fs/namespace.c:3078
       do_mount fs/namespace.c:3421 [inline]
       __do_sys_mount fs/namespace.c:3629 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3606
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&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:463
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6805
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3b6/0xcb0 fs/quota/dquot.c:1517
       ext4_mkdir+0x16c/0xc50 fs/ext4/namei.c:3059
       vfs_mkdir+0x387/0x570 fs/namei.c:4114
       do_mkdirat+0x1d0/0x430 fs/namei.c:4139
       __do_sys_mkdirat fs/namei.c:4154 [inline]
       __se_sys_mkdirat fs/namei.c:4152 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4152
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6785
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0x1e3/0x400 fs/quota/dquot.c:412
       __dquot_alloc_space+0x5fc/0xe60 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+0xf74/0x4720 fs/ext4/mballoc.c:5722
       ext4_new_meta_blocks+0x151/0x3a0 fs/ext4/balloc.c:739
       ext4_ext_grow_indepth fs/ext4/extents.c:1331 [inline]
       ext4_ext_create_new_leaf fs/ext4/extents.c:1437 [inline]
       ext4_ext_insert_extent+0x1048/0x4740 fs/ext4/extents.c:2105
       ext4_split_extent_at+0x7ab/0xf60 fs/ext4/extents.c:3236
       ext4_force_split_extent_at fs/ext4/extents.c:338 [inline]
       ext4_swap_extents+0x1103/0x1c80 fs/ext4/extents.c:5773
       move_extent_per_page+0x1f63/0x47e0 fs/ext4/move_extent.c:367
       ext4_move_extents+0x89a/0xb90 fs/ext4/move_extent.c:678
       __ext4_ioctl fs/ext4/ioctl.c:1358 [inline]
       ext4_ioctl+0x3501/0x3dd0 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ei->i_data_sem/1){+.+.}-{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+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
       ext4_move_extents+0x325/0xb90 fs/ext4/move_extent.c:615
       __ext4_ioctl fs/ext4/ioctl.c:1358 [inline]
       ext4_ioctl+0x3501/0x3dd0 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  &ei->i_data_sem/1 --> &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(&ei->i_data_sem/1);

 *** DEADLOCK ***

4 locks held by syz.1.1595/11789:
 #0: ffff88802f912460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:446
 #1: ffff88804ee00e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff88804ee00e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xd5/0x150 fs/inode.c:1208
 #2: ffff88804ee03628 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: ext4_move_extents+0x30a/0xb90 fs/ext4/move_extent.c:608
 #3: ffff88804ee00c90 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40 fs/ext4/move_extent.c:-1

stack backtrace:
CPU: 1 PID: 11789 Comm: syz.1.1595 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
 ext4_move_extents+0x325/0xb90 fs/ext4/move_extent.c:615
 __ext4_ioctl fs/ext4/ioctl.c:1358 [inline]
 ext4_ioctl+0x3501/0x3dd0 fs/ext4/ioctl.c:1614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6f6ad8f6c9
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:00007f6f6bb80038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6f6afe6270 RCX: 00007f6f6ad8f6c9
RDX: 0000200000000100 RSI: 00000000c028660f RDI: 000000000000000b
RBP: 00007f6f6ae11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6f6afe6308 R14: 00007f6f6afe6270 R15: 00007ffec1b67198
 </TASK>