syzbot

loop0: detected capacity change from 0 to 512
EXT4-fs (loop0): orphan cleanup on readonly fs
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.93/4564 is trying to acquire lock:
ffff88806b541e68 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_commit+0x5a/0x410 fs/quota/dquot.c:507

but task is already holding lock:
ffff88806b768c90 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x987/0x1230 fs/ext4/inode.c:4284

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+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:7157
       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+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:6812
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3b6/0xcb0 fs/quota/dquot.c:1517
       ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xbd3/0x1400 fs/ext4/orphan.c:474
       __ext4_fill_super fs/ext4/super.c:5537 [inline]
       ext4_fill_super+0x7bc2/0x8150 fs/ext4/super.c:5668
       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:3069
       do_mount fs/namespace.c:3412 [inline]
       __do_sys_mount fs/namespace.c:3620 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3597
       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 (&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:6812
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3b6/0xcb0 fs/quota/dquot.c:1517
       ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xbd3/0x1400 fs/ext4/orphan.c:474
       __ext4_fill_super fs/ext4/super.c:5537 [inline]
       ext4_fill_super+0x7bc2/0x8150 fs/ext4/super.c:5668
       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:3069
       do_mount fs/namespace.c:3412 [inline]
       __do_sys_mount fs/namespace.c:3620 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3597
       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 (&dquot->dq_lock){+.+.}-{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
       __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:6792
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
       __dquot_free_space+0x7ec/0xbc0 fs/quota/dquot.c:1942
       dquot_free_space_nodirty include/linux/quotaops.h:379 [inline]
       dquot_free_space include/linux/quotaops.h:384 [inline]
       dquot_free_block include/linux/quotaops.h:395 [inline]
       ext4_mb_clear_bb fs/ext4/mballoc.c:6138 [inline]
       ext4_free_blocks+0x1bab/0x2640 fs/ext4/mballoc.c:6268
       ext4_remove_blocks fs/ext4/extents.c:2526 [inline]
       ext4_ext_rm_leaf fs/ext4/extents.c:2692 [inline]
       ext4_ext_remove_space+0x1f0d/0x4490 fs/ext4/extents.c:2940
       ext4_ext_truncate+0x211/0x370 fs/ext4/extents.c:4470
       ext4_truncate+0xa0b/0x1230 fs/ext4/inode.c:4289
       ext4_evict_inode+0xb35/0x1100 fs/ext4/inode.c:286
       evict+0x485/0x870 fs/inode.c:705
       ext4_orphan_cleanup+0xbd3/0x1400 fs/ext4/orphan.c:474
       __ext4_fill_super fs/ext4/super.c:5537 [inline]
       ext4_fill_super+0x7bc2/0x8150 fs/ext4/super.c:5668
       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:3069
       do_mount fs/namespace.c:3412 [inline]
       __do_sys_mount fs/namespace.c:3620 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3597
       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:
  &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.0.93/4564:
 #0: ffff88807bff00e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
 #1: ffff88807bff0650 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1891 [inline]
 #1: ffff88807bff0650 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:2013 [inline]
 #1: ffff88807bff0650 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x436/0x1100 fs/ext4/inode.c:240
 #2: ffff88806b768c90 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x987/0x1230 fs/ext4/inode.c:4284
 #3: ffffffff8cc71c88 (dquot_srcu){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #3: ffffffff8cc71c88 (dquot_srcu){....}-{0:0}, at: srcu_read_lock include/linux/srcu.h:165 [inline]
 #3: ffffffff8cc71c88 (dquot_srcu){....}-{0:0}, at: __dquot_free_space+0x174/0xbc0 fs/quota/dquot.c:1915

stack backtrace:
CPU: 0 PID: 4564 Comm: syz.0.93 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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
 __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:6792
 mark_dquot_dirty fs/quota/dquot.c:372 [inline]
 mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
 __dquot_free_space+0x7ec/0xbc0 fs/quota/dquot.c:1942
 dquot_free_space_nodirty include/linux/quotaops.h:379 [inline]
 dquot_free_space include/linux/quotaops.h:384 [inline]
 dquot_free_block include/linux/quotaops.h:395 [inline]
 ext4_mb_clear_bb fs/ext4/mballoc.c:6138 [inline]
 ext4_free_blocks+0x1bab/0x2640 fs/ext4/mballoc.c:6268
 ext4_remove_blocks fs/ext4/extents.c:2526 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2692 [inline]
 ext4_ext_remove_space+0x1f0d/0x4490 fs/ext4/extents.c:2940
 ext4_ext_truncate+0x211/0x370 fs/ext4/extents.c:4470
 ext4_truncate+0xa0b/0x1230 fs/ext4/inode.c:4289
 ext4_evict_inode+0xb35/0x1100 fs/ext4/inode.c:286
 evict+0x485/0x870 fs/inode.c:705
 ext4_orphan_cleanup+0xbd3/0x1400 fs/ext4/orphan.c:474
 __ext4_fill_super fs/ext4/super.c:5537 [inline]
 ext4_fill_super+0x7bc2/0x8150 fs/ext4/super.c:5668
 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:3069
 do_mount fs/namespace.c:3412 [inline]
 __do_sys_mount fs/namespace.c:3620 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3597
 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: 0033:0x7f8d1299066a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc55343a28 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc55343ab0 RCX: 00007f8d1299066a
RDX: 0000200000000040 RSI: 0000200000000000 RDI: 00007ffc55343a70
RBP: 0000200000000040 R08: 00007ffc55343ab0 R09: 0000000000004517
R10: 0000000000004517 R11: 0000000000000246 R12: 0000200000000000
R13: 00007ffc55343a70 R14: 00000000000004b3 R15: 0000200000000b40
 </TASK>
EXT4-fs (loop0): 1 orphan inode deleted