syzbot

EXT4-fs error (device loop0): ext4_do_update_inode:5279: inode #3: comm syz.0.79: corrupted inode contents
EXT4-fs error (device loop0): ext4_dirty_inode:6156: inode #3: comm syz.0.79: mark_inode_dirty error
EXT4-fs error (device loop0): ext4_do_update_inode:5279: inode #3: comm syz.0.79: corrupted inode contents
EXT4-fs error (device loop0): __ext4_ext_dirty:202: inode #3: comm syz.0.79: mark_inode_dirty error
EXT4-fs error (device loop0): ext4_acquire_dquot:6841: comm syz.0.79: Failed to acquire dquot type 0
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.79/4533 is trying to acquire lock:
ffff88806e64b928 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_commit+0x5a/0x410 fs/quota/dquot.c:507

but task is already holding lock:
ffff88805ac352c8 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x999/0x1240 fs/ext4/inode.c:4297

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+0x323/0x1b70 fs/ext4/inode.c:606
       ext4_getblk+0x1cc/0x6f0 fs/ext4/inode.c:892
       ext4_bread+0x26/0x170 fs/ext4/inode.c:948
       ext4_quota_write+0x236/0x580 fs/ext4/super.c:7228
       write_blk fs/quota/quota_tree.c:70 [inline]
       get_free_dqblk+0x312/0x660 fs/quota/quota_tree.c:136
       do_insert_tree+0x22b/0x1040 fs/quota/quota_tree.c:347
       do_insert_tree+0x9eb/0x1040 fs/quota/quota_tree.c:402
       do_insert_tree+0x9eb/0x1040 fs/quota/quota_tree.c:402
       do_insert_tree+0x9eb/0x1040 fs/quota/quota_tree.c:402
       dq_insert_tree fs/quota/quota_tree.c:432 [inline]
       qtree_write_dquot+0x49d/0x5d0 fs/quota/quota_tree.c:451
       v2_write_dquot+0x108/0x190 fs/quota/quota_v2.c:361
       dquot_acquire+0x2d5/0x520 fs/quota/dquot.c:472
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6837
       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:5574 [inline]
       ext4_fill_super+0x6ee3/0x78c0 fs/ext4/super.c:5693
       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 (&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:6837
       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:5574 [inline]
       ext4_fill_super+0x6ee3/0x78c0 fs/ext4/super.c:5693
       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

-> #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+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       __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:6817
       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:6153 [inline]
       ext4_free_blocks+0x1bf3/0x26a0 fs/ext4/mballoc.c:6283
       ext4_remove_blocks fs/ext4/extents.c:2526 [inline]
       ext4_ext_rm_leaf fs/ext4/extents.c:2692 [inline]
       ext4_ext_remove_space+0x225f/0x44c0 fs/ext4/extents.c:2940
       ext4_ext_truncate+0x211/0x370 fs/ext4/extents.c:4476
       ext4_truncate+0xa23/0x1240 fs/ext4/inode.c:4302
       ext4_evict_inode+0xb41/0x1110 fs/ext4/inode.c:288
       evict+0x4c9/0x8d0 fs/inode.c:705
       ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5574 [inline]
       ext4_fill_super+0x6ee3/0x78c0 fs/ext4/super.c:5693
       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:
  &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.0.79/4533:
 #0: ffff88807ddaa0e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
 #1: ffff88807ddaa650 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1891 [inline]
 #1: ffff88807ddaa650 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:2013 [inline]
 #1: ffff88807ddaa650 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x43c/0x1110 fs/ext4/inode.c:242
 #2: ffff88805ac352c8 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x999/0x1240 fs/ext4/inode.c:4297
 #3: ffffffff8cc75248 (dquot_srcu){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #3: ffffffff8cc75248 (dquot_srcu){....}-{0:0}, at: srcu_read_lock include/linux/srcu.h:165 [inline]
 #3: ffffffff8cc75248 (dquot_srcu){....}-{0:0}, at: __dquot_free_space+0x174/0xbc0 fs/quota/dquot.c:1915

stack backtrace:
CPU: 1 PID: 4533 Comm: syz.0.79 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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
 __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:6817
 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:6153 [inline]
 ext4_free_blocks+0x1bf3/0x26a0 fs/ext4/mballoc.c:6283
 ext4_remove_blocks fs/ext4/extents.c:2526 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2692 [inline]
 ext4_ext_remove_space+0x225f/0x44c0 fs/ext4/extents.c:2940
 ext4_ext_truncate+0x211/0x370 fs/ext4/extents.c:4476
 ext4_truncate+0xa23/0x1240 fs/ext4/inode.c:4302
 ext4_evict_inode+0xb41/0x1110 fs/ext4/inode.c:288
 evict+0x4c9/0x8d0 fs/inode.c:705
 ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5574 [inline]
 ext4_fill_super+0x6ee3/0x78c0 fs/ext4/super.c:5693
 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: 0033:0x7f4b8d39e0ca
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:00007ffebba54b58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffebba54be0 RCX: 00007f4b8d39e0ca
RDX: 0000200000000100 RSI: 0000200000000200 RDI: 00007ffebba54ba0
RBP: 0000200000000100 R08: 00007ffebba54be0 R09: 0000000002000005
R10: 0000000002000005 R11: 0000000000000246 R12: 0000200000000200
R13: 00007ffebba54ba0 R14: 00000000000004fa R15: 0000200000003140
 </TASK>
EXT4-fs (loop0): 1 orphan inode deleted