syzbot

loop4: detected capacity change from 0 to 128
EXT4-fs (loop4): mounted filesystem without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.3181/17559 is trying to acquire lock:
ffff888073ea2aa8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_move_extents+0x32b/0xbe0 fs/ext4/move_extent.c:615

but task is already holding lock:
ffff8880541a20a0 (&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+0x338/0x1a90 fs/ext4/inode.c:606
       ext4_getblk+0x1c5/0x720 fs/ext4/inode.c:892
       ext4_bread+0x26/0x170 fs/ext4/inode.c:948
       ext4_quota_read+0x17f/0x380 fs/ext4/super.c:7182
       read_blk fs/quota/quota_tree.c:61 [inline]
       find_tree_dqentry+0x1cc/0xf40 fs/quota/quota_tree.c:671
       find_tree_dqentry+0x6ac/0xf40 fs/quota/quota_tree.c:698
       find_dqentry fs/quota/quota_tree.c:716 [inline]
       qtree_read_dquot+0x59a/0x880 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:488
       ext4_acquire_dquot+0x2e3/0x4a0 fs/ext4/super.c:6837
       dqget+0x713/0xbb0 fs/quota/dquot.c:1010
       __dquot_initialize+0x3a9/0xd00 fs/quota/dquot.c:1539
       ext4_process_orphan+0x4c/0x2e0 fs/ext4/orphan.c:327
       ext4_orphan_cleanup+0xc32/0x1470 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5574 [inline]
       ext4_fill_super+0x6f0c/0x78f0 fs/ext4/super.c:5693
       get_tree_bdev+0x3e6/0x610 fs/super.c:1366
       vfs_get_tree+0x88/0x270 fs/super.c:1573
       do_new_mount+0x247/0xa40 fs/namespace.c:3078
       do_mount fs/namespace.c:3421 [inline]
       __do_sys_mount fs/namespace.c:3629 [inline]
       __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606
       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

-> #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:488
       ext4_acquire_dquot+0x2e3/0x4a0 fs/ext4/super.c:6837
       dqget+0x713/0xbb0 fs/quota/dquot.c:1010
       __dquot_initialize+0x3a9/0xd00 fs/quota/dquot.c:1539
       ext4_process_orphan+0x4c/0x2e0 fs/ext4/orphan.c:327
       ext4_orphan_cleanup+0xc32/0x1470 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5574 [inline]
       ext4_fill_super+0x6f0c/0x78f0 fs/ext4/super.c:5693
       get_tree_bdev+0x3e6/0x610 fs/super.c:1366
       vfs_get_tree+0x88/0x270 fs/super.c:1573
       do_new_mount+0x247/0xa40 fs/namespace.c:3078
       do_mount fs/namespace.c:3421 [inline]
       __do_sys_mount fs/namespace.c:3629 [inline]
       __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606
       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 (&dquot->dq_lock){+.+.}-{3:3}:
       __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:532
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6817
       mark_dquot_dirty fs/quota/dquot.c:397 [inline]
       mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:437
       __dquot_free_space+0x7f8/0xbc0 fs/quota/dquot.c:1964
       dquot_free_space_nodirty include/linux/quotaops.h:372 [inline]
       dquot_free_space+0x1b/0x30 include/linux/quotaops.h:377
       swap_inode_boot_loader+0xc61/0x10f0 fs/ext4/ioctl.c:492
       __ext4_ioctl fs/ext4/ioctl.c:1427 [inline]
       ext4_ioctl+0x1e66/0x4140 fs/ext4/ioctl.c:1617
       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:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ei->i_data_sem/1){+.+.}-{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
       down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
       ext4_move_extents+0x32b/0xbe0 fs/ext4/move_extent.c:615
       __ext4_ioctl fs/ext4/ioctl.c:1361 [inline]
       ext4_ioctl+0x37fe/0x4140 fs/ext4/ioctl.c:1617
       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: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:
  &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.4.3181/17559:
 #0: ffff888062ff4460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:446
 #1: ffff8880541a2218 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff8880541a2218 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: lock_two_nondirectories+0xf7/0x150 fs/inode.c:1208
 #2: ffff888073ea2c20 (&sb->s_type->i_mutex_key#9/4){+.+.}-{3:3}, at: ext4_move_extents+0x310/0xbe0 fs/ext4/move_extent.c:608
 #3: ffff8880541a20a0 (&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: 17559 Comm: syz.4.3181 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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
 down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
 ext4_move_extents+0x32b/0xbe0 fs/ext4/move_extent.c:615
 __ext4_ioctl fs/ext4/ioctl.c:1361 [inline]
 ext4_ioctl+0x37fe/0x4140 fs/ext4/ioctl.c:1617
 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:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6e5579de59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6e566ba028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6e55a25fa0 RCX: 00007f6e5579de59
RDX: 0000200000000040 RSI: 00000000c028660f RDI: 0000000000000005
RBP: 00007f6e55833e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e55a26038 R14: 00007f6e55a25fa0 R15: 00007fffaa5edd58
 </TASK>