======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.1841/12696 is trying to acquire lock:
ffff8880704848c0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x323/0x1b70 fs/ext4/inode.c:604

but task is already holding lock:
ffff88805406a208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_read_dquot+0x4a/0x110 fs/quota/quota_v2.c:335

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+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:6831
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3c3/0xcd0 fs/quota/dquot.c:1517
       ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:327
       ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5556 [inline]
       ext4_fill_super+0x7829/0x7dc0 fs/ext4/super.c:5687
       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+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/0xaf0 kernel/locking/mutex.c:747
       dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6811
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf9/0x400 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+0xf8d/0x4760 fs/ext4/mballoc.c:5738
       ext4_ext_map_blocks+0x195b/0x6810 fs/ext4/extents.c:4340
       ext4_map_blocks+0x9de/0x1b70 fs/ext4/inode.c:679
       _ext4_get_block+0x1e7/0x540 fs/ext4/inode.c:822
       ext4_get_block_unwritten+0x2a/0x100 fs/ext4/inode.c:855
       __block_write_begin_int+0x55d/0x1a80 fs/buffer.c:1991
       ext4_convert_inline_data_to_extent fs/ext4/ext4_jbd2.h:-1 [inline]
       ext4_try_to_write_inline_data+0x81b/0x1150 fs/ext4/inline.c:761
       ext4_write_begin+0x28f/0xf80 fs/ext4/inode.c:1204
       ext4_da_write_begin+0x30a/0x960 fs/ext4/inode.c:3000
       generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862
       ext4_buffered_write_iter+0x11a/0x390 fs/ext4/file.c:285
       ext4_file_write_iter+0x1cf/0x1710 fs/ext4/file.c:-1
       do_iter_readv_writev fs/read_write.c:-1 [inline]
       do_iter_write+0x642/0xb10 fs/read_write.c:861
       vfs_writev fs/read_write.c:934 [inline]
       do_pwritev+0x23d/0x3a0 fs/read_write.c:1031
       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/2){++++}-{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+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       ext4_map_blocks+0x323/0x1b70 fs/ext4/inode.c:604
       ext4_getblk+0x1cc/0x6f0 fs/ext4/inode.c:890
       ext4_bread+0x26/0x170 fs/ext4/inode.c:946
       ext4_quota_read+0x180/0x380 fs/ext4/super.c:7176
       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_dqentry fs/quota/quota_tree.c:716 [inline]
       qtree_read_dquot+0x57b/0x820 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:6831
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3c3/0xcd0 fs/quota/dquot.c:1517
       ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:327
       ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5556 [inline]
       ext4_fill_super+0x7829/0x7dc0 fs/ext4/super.c:5687
       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+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

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 ***

3 locks held by syz.4.1841/12696:
 #0: ffff88805406a0e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
 #1: ffff888054e24428 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_acquire+0x63/0x520 fs/quota/dquot.c:460
 #2: ffff88805406a208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_read_dquot+0x4a/0x110 fs/quota/quota_v2.c:335

stack backtrace:
CPU: 0 PID: 12696 Comm: syz.4.1841 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
 ext4_map_blocks+0x323/0x1b70 fs/ext4/inode.c:604
 ext4_getblk+0x1cc/0x6f0 fs/ext4/inode.c:890
 ext4_bread+0x26/0x170 fs/ext4/inode.c:946
 ext4_quota_read+0x180/0x380 fs/ext4/super.c:7176
 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_dqentry fs/quota/quota_tree.c:716 [inline]
 qtree_read_dquot+0x57b/0x820 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:6831
 dqget+0x778/0xeb0 fs/quota/dquot.c:988
 __dquot_initialize+0x3c3/0xcd0 fs/quota/dquot.c:1517
 ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:327
 ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5556 [inline]
 ext4_fill_super+0x7829/0x7dc0 fs/ext4/super.c:5687
 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+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
RIP: 0033:0x7f3c05b9d20a
Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 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:00007f3c069eee58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f3c069eeee0 RCX: 00007f3c05b9d20a
RDX: 0000200000000040 RSI: 0000200000000000 RDI: 00007f3c069eeea0
RBP: 0000200000000040 R08: 00007f3c069eeee0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000000
R13: 00007f3c069eeea0 R14: 00000000000004fc R15: 0000200000000640
 </TASK>
EXT4-fs error (device loop4): ext4_mb_generate_buddy:1113: group 0, block bitmap and bg descriptor inconsistent: 18 vs 41 free clusters
Quota error (device loop4): write_blk: dquota write failed
Quota error (device loop4): qtree_write_dquot: Error -28 occurred while creating quota
EXT4-fs error (device loop4): ext4_acquire_dquot:6835: comm syz.4.1841: Failed to acquire dquot type 0
EXT4-fs (loop4): 1 truncate cleaned up
EXT4-fs (loop4): mounted filesystem without journal. Quota mode: writeback.