syzbot

loop0: detected capacity change from 0 to 512
ext4 filesystem being mounted at /116/file1 supports timestamps until 2038-01-19 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.133/4699 is trying to acquire lock:
ffff88805ca39ca8 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_commit+0x5a/0x410 fs/quota/dquot.c:507

but task is already holding lock:
ffff88805c8d8c70 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x96d/0x10d0 fs/ext4/inode.c:4251

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+0x44/0x2e0 kernel/locking/rwsem.c:1498
       ext4_map_blocks+0x32f/0x1b30 fs/ext4/inode.c:598
       ext4_getblk+0x16d/0x630 fs/ext4/inode.c:870
       ext4_bread+0x26/0x180 fs/ext4/inode.c:923
       ext4_quota_read+0x1b3/0x3a0 fs/ext4/super.c:6550
       read_blk fs/quota/quota_tree.c:55 [inline]
       find_tree_dqentry+0x188/0xb30 fs/quota/quota_tree.c:617
       find_tree_dqentry+0x3eb/0xb30 fs/quota/quota_tree.c:635
       find_tree_dqentry+0x3eb/0xb30 fs/quota/quota_tree.c:635
       find_tree_dqentry+0x3eb/0xb30 fs/quota/quota_tree.c:635
       find_dqentry fs/quota/quota_tree.c:647 [inline]
       qtree_read_dquot+0x13c/0x680 fs/quota/quota_tree.c:667
       v2_read_dquot+0xc0/0x110 fs/quota/quota_v2.c:333
       dquot_acquire+0x152/0x520 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6205
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       dquot_get_dqblk+0x27/0x2c0 fs/quota/dquot.c:2692
       quota_getquota+0x256/0x4c0 fs/quota/quota.c:213
       __do_sys_quotactl fs/quota/quota.c:959 [inline]
       __se_sys_quotactl+0x295/0x6c0 fs/quota/quota.c:915
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       v2_read_dquot+0x4a/0x110 fs/quota/quota_v2.c:332
       dquot_acquire+0x152/0x520 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6205
       dqget+0x778/0xeb0 fs/quota/dquot.c:988
       __dquot_initialize+0x3b6/0xcb0 fs/quota/dquot.c:1517
       ext4_rename fs/ext4/namei.c:3882 [inline]
       ext4_rename2+0x6b3/0x3000 fs/ext4/namei.c:4272
       vfs_rename+0xbbf/0x10d0 fs/namei.c:4840
       do_renameat2+0xa83/0xf70 fs/namei.c:4993
       __do_sys_rename fs/namei.c:5039 [inline]
       __se_sys_rename fs/namei.c:5037 [inline]
       __x64_sys_rename+0x82/0x90 fs/namei.c:5037
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&dquot->dq_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
       ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6185
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
       __dquot_free_space+0x7ca/0xb90 fs/quota/dquot.c:1942
       dquot_free_space_nodirty include/linux/quotaops.h:376 [inline]
       dquot_free_space include/linux/quotaops.h:381 [inline]
       dquot_free_block include/linux/quotaops.h:392 [inline]
       ext4_mb_clear_bb fs/ext4/mballoc.c:6151 [inline]
       ext4_free_blocks+0x1af5/0x2480 fs/ext4/mballoc.c:6281
       ext4_remove_blocks fs/ext4/extents.c:2525 [inline]
       ext4_ext_rm_leaf fs/ext4/extents.c:2691 [inline]
       ext4_ext_remove_space+0x1eaa/0x43a0 fs/ext4/extents.c:2939
       ext4_ext_truncate+0x192/0x240 fs/ext4/extents.c:4473
       ext4_truncate+0x9f1/0x10d0 fs/ext4/inode.c:4256
       ext4_evict_inode+0xb43/0x1080 fs/ext4/inode.c:289
       evict+0x485/0x870 fs/inode.c:647
       __dentry_kill+0x431/0x650 fs/dcache.c:586
       dentry_kill+0xb8/0x290 fs/dcache.c:-1
       dput+0xd8/0x1a0 fs/dcache.c:893
       do_renameat2+0x704/0xf70 fs/namei.c:4995
       __do_sys_rename fs/namei.c:5039 [inline]
       __se_sys_rename fs/namei.c:5037 [inline]
       __x64_sys_rename+0x82/0x90 fs/namei.c:5037
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.0.133/4699:
 #0: ffff888078d32460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff88805c912bd0 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: lock_rename include/linux/fs.h:-1 [inline]
 #1: ffff88805c912bd0 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: do_renameat2+0x42a/0xf70 fs/namei.c:4932
 #2: ffff888078d32650 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline]
 #2: ffff888078d32650 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1928 [inline]
 #2: ffff888078d32650 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x444/0x1080 fs/ext4/inode.c:243
 #3: ffff88805c8d8c70 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_truncate+0x96d/0x10d0 fs/ext4/inode.c:4251
 #4: ffffffff8c23f0d8 (dquot_srcu){....}-{0:0}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312

stack backtrace:
CPU: 1 PID: 4699 Comm: syz.0.133 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 dquot_commit+0x5a/0x410 fs/quota/dquot.c:507
 ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6185
 mark_dquot_dirty fs/quota/dquot.c:372 [inline]
 mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412
 __dquot_free_space+0x7ca/0xb90 fs/quota/dquot.c:1942
 dquot_free_space_nodirty include/linux/quotaops.h:376 [inline]
 dquot_free_space include/linux/quotaops.h:381 [inline]
 dquot_free_block include/linux/quotaops.h:392 [inline]
 ext4_mb_clear_bb fs/ext4/mballoc.c:6151 [inline]
 ext4_free_blocks+0x1af5/0x2480 fs/ext4/mballoc.c:6281
 ext4_remove_blocks fs/ext4/extents.c:2525 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2691 [inline]
 ext4_ext_remove_space+0x1eaa/0x43a0 fs/ext4/extents.c:2939
 ext4_ext_truncate+0x192/0x240 fs/ext4/extents.c:4473
 ext4_truncate+0x9f1/0x10d0 fs/ext4/inode.c:4256
 ext4_evict_inode+0xb43/0x1080 fs/ext4/inode.c:289
 evict+0x485/0x870 fs/inode.c:647
 __dentry_kill+0x431/0x650 fs/dcache.c:586
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xd8/0x1a0 fs/dcache.c:893
 do_renameat2+0x704/0xf70 fs/namei.c:4995
 __do_sys_rename fs/namei.c:5039 [inline]
 __se_sys_rename fs/namei.c:5037 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5037
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fa3a14fc749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffec9ac69d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007fa3a1752fa0 RCX: 00007fa3a14fc749
RDX: 0000000000000000 RSI: 0000200000000300 RDI: 0000200000000000
RBP: 00007fa3a1580f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3a1752fa0 R14: 00007fa3a1752fa0 R15: 0000000000000002
 </TASK>
EXT4-fs (loop0): re-mounted. Opts: (null). Quota mode: writeback.