ext4 filesystem being mounted at /478/bus supports timestamps until 2038-01-19 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.8.4577/24356 is trying to acquire lock:
ffff8880555b1768 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_commit+0x5a/0x410 fs/quota/dquot.c:507

but task is already holding lock:
ffff88805c3fc8c0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x999/0x1240 fs/ext4/inode.c:4290

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_write+0x36/0x60 kernel/locking/rwsem.c:1573
       ext4_map_blocks+0x910/0x1b70 fs/ext4/inode.c:672
       ext4_getblk+0x1cc/0x6f0 fs/ext4/inode.c:890
       ext4_bread+0x26/0x170 fs/ext4/inode.c:946
       ext4_quota_write+0x236/0x580 fs/ext4/super.c:7222
       write_blk fs/quota/quota_tree.c:70 [inline]
       find_free_dqentry+0x673/0xc20 fs/quota/quota_tree.c:318
       do_insert_tree+0x70d/0x1040 fs/quota/quota_tree.c:400
       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: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 (&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

-> #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:6811
       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:6154 [inline]
       ext4_free_blocks+0x1bf3/0x26a0 fs/ext4/mballoc.c:6284
       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:4470
       ext4_truncate+0xa23/0x1240 fs/ext4/inode.c:4295
       ext4_setattr+0x10cb/0x19f0 fs/ext4/inode.c:5649
       notify_change+0xc74/0xf40 fs/attr.c:499
       do_truncate+0x1ac/0x240 fs/open.c:65
       handle_truncate fs/namei.c:3293 [inline]
       do_open fs/namei.c:3638 [inline]
       path_openat+0x2861/0x2ee0 fs/namei.c:3791
       do_filp_open+0x1f1/0x430 fs/namei.c:3818
       do_sys_openat2+0x150/0x4b0 fs/open.c:1320
       do_sys_open fs/open.c:1336 [inline]
       __do_sys_openat fs/open.c:1352 [inline]
       __se_sys_openat fs/open.c:1347 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1347
       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 ***

5 locks held by syz.8.4577/24356:
 #0: ffff888056dd2460 (sb_writers#4){++++}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402
 #1: ffff88805c3fca38 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff88805c3fca38 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: do_truncate+0x198/0x240 fs/open.c:63
 #2: ffff88805c3fcbd8 (mapping.invalidate_lock#2){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:803 [inline]
 #2: ffff88805c3fcbd8 (mapping.invalidate_lock#2){++++}-{3:3}, at: ext4_setattr+0xe6f/0x19f0 fs/ext4/inode.c:5572
 #3: ffff88805c3fc8c0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x999/0x1240 fs/ext4/inode.c:4290
 #4: ffffffff8cc74988 (dquot_srcu){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #4: ffffffff8cc74988 (dquot_srcu){....}-{0:0}, at: srcu_read_lock include/linux/srcu.h:165 [inline]
 #4: ffffffff8cc74988 (dquot_srcu){....}-{0:0}, at: __dquot_free_space+0x174/0xbc0 fs/quota/dquot.c:1915

stack backtrace:
CPU: 0 PID: 24356 Comm: syz.8.4577 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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:6811
 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:6154 [inline]
 ext4_free_blocks+0x1bf3/0x26a0 fs/ext4/mballoc.c:6284
 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:4470
 ext4_truncate+0xa23/0x1240 fs/ext4/inode.c:4295
 ext4_setattr+0x10cb/0x19f0 fs/ext4/inode.c:5649
 notify_change+0xc74/0xf40 fs/attr.c:499
 do_truncate+0x1ac/0x240 fs/open.c:65
 handle_truncate fs/namei.c:3293 [inline]
 do_open fs/namei.c:3638 [inline]
 path_openat+0x2861/0x2ee0 fs/namei.c:3791
 do_filp_open+0x1f1/0x430 fs/namei.c:3818
 do_sys_openat2+0x150/0x4b0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 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: 0033:0x7f98e019aeb9
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:00007f98de3f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f98e0415fa0 RCX: 00007f98e019aeb9
RDX: 0000000000080602 RSI: 0000200000000180 RDI: ffffffffffffff9c
RBP: 00007f98e0208c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000148 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f98e0416038 R14: 00007f98e0415fa0 R15: 00007ffe2e4d1068
 </TASK>