loop2: detected capacity change from 0 to 512
EXT4-fs (loop2): feature flags set on rev 0 fs, running e2fsck is recommended
[EXT4 FS bs=4096, gc=1, bpg=3008, ipg=32, mo=8001e119, mo2=0000]
======================================================
WARNING: possible circular locking dependency detected
5.15.173-syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1006/7148 is trying to acquire lock:
ffff88805bc98c70 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x391/0x1c70 fs/ext4/inode.c:597

but task is already holding lock:
ffff88801c252208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       down_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
       v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2eb/0x4a0 fs/ext4/super.c:6193
       dqget+0x762/0xe90 fs/quota/dquot.c:986
       __dquot_initialize+0x2d9/0xea0 fs/quota/dquot.c:1515
       ext4_create+0xb1/0x550 fs/ext4/namei.c:2876
       lookup_open fs/namei.c:3462 [inline]
       open_last_lookups fs/namei.c:3532 [inline]
       path_openat+0x130a/0x2f20 fs/namei.c:3739
       do_filp_open+0x21c/0x460 fs/namei.c:3769
       do_sys_openat2+0x13b/0x4f0 fs/open.c:1253
       do_sys_open fs/open.c:1269 [inline]
       __do_sys_openat fs/open.c:1285 [inline]
       __se_sys_openat fs/open.c:1280 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1280
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 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+0x57/0x510 fs/quota/dquot.c:507
       ext4_write_dquot+0x1fd/0x360 fs/ext4/super.c:6173
       mark_dquot_dirty fs/quota/dquot.c:372 [inline]
       mark_all_dquot_dirty+0xf7/0x400 fs/quota/dquot.c:412
       __dquot_alloc_space+0xdd8/0x1090 fs/quota/dquot.c:1750
       dquot_alloc_space_nodirty include/linux/quotaops.h:297 [inline]
       dquot_alloc_space include/linux/quotaops.h:310 [inline]
       dquot_alloc_block include/linux/quotaops.h:334 [inline]
       ext4_mb_new_blocks+0x12d8/0x4d60 fs/ext4/mballoc.c:5739
       ext4_ext_map_blocks+0x1b01/0x7630 fs/ext4/extents.c:4339
       ext4_map_blocks+0xa66/0x1c70 fs/ext4/inode.c:672
       _ext4_get_block+0x23b/0x660 fs/ext4/inode.c:815
       ext4_block_write_begin+0x6b0/0x13a0 fs/ext4/inode.c:1100
       ext4_write_begin+0x6c6/0x15f0
       ext4_da_write_begin+0x342/0xb60 fs/ext4/inode.c:2974
       generic_perform_write+0x2bf/0x5b0 mm/filemap.c:3785
       ext4_buffered_write_iter+0x227/0x360 fs/ext4/file.c:268
       ext4_file_write_iter+0x1d1/0x1940 fs/ext4/file.c:662
       call_write_iter include/linux/fs.h:2174 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0xacd/0xe50 fs/read_write.c:594
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&ei->i_data_sem/2){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       down_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
       ext4_map_blocks+0x391/0x1c70 fs/ext4/inode.c:597
       ext4_getblk+0x19f/0x710 fs/ext4/inode.c:869
       ext4_bread+0x2a/0x170 fs/ext4/inode.c:922
       ext4_quota_read+0x1a1/0x2c0 fs/ext4/super.c:6521
       read_blk fs/quota/quota_tree.c:55 [inline]
       find_tree_dqentry+0x192/0xb60 fs/quota/quota_tree.c:617
       find_tree_dqentry+0x41a/0xb60 fs/quota/quota_tree.c:635
       find_dqentry fs/quota/quota_tree.c:647 [inline]
       qtree_read_dquot+0x13f/0x650 fs/quota/quota_tree.c:667
       v2_read_dquot+0xbe/0x100 fs/quota/quota_v2.c:333
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:463
       ext4_acquire_dquot+0x2eb/0x4a0 fs/ext4/super.c:6193
       dqget+0x762/0xe90 fs/quota/dquot.c:986
       __dquot_initialize+0x2d9/0xea0 fs/quota/dquot.c:1515
       ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0x9d9/0x1240 fs/ext4/orphan.c:474
       ext4_fill_super+0x98de/0xa110 fs/ext4/super.c:4975
       mount_bdev+0x2c9/0x3f0 fs/super.c:1400
       legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
       vfs_get_tree+0x88/0x270 fs/super.c:1530
       do_new_mount+0x2ba/0xb40 fs/namespace.c:3012
       do_mount fs/namespace.c:3355 [inline]
       __do_sys_mount fs/namespace.c:3563 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3540
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.2.1006/7148:
 #0: ffff88801c2520e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x210/0x940 fs/super.c:229
 #1: ffff88805bc885e8 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_acquire+0x64/0x680 fs/quota/dquot.c:460
 #2: ffff88801c252208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332

stack backtrace:
CPU: 0 PID: 7148 Comm: syz.2.1006 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 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+0x1649/0x5930 kernel/locking/lockdep.c:3788
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 down_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
 ext4_map_blocks+0x391/0x1c70 fs/ext4/inode.c:597
 ext4_getblk+0x19f/0x710 fs/ext4/inode.c:869
 ext4_bread+0x2a/0x170 fs/ext4/inode.c:922
 ext4_quota_read+0x1a1/0x2c0 fs/ext4/super.c:6521
 read_blk fs/quota/quota_tree.c:55 [inline]
 find_tree_dqentry+0x192/0xb60 fs/quota/quota_tree.c:617
 find_tree_dqentry+0x41a/0xb60 fs/quota/quota_tree.c:635
 find_dqentry fs/quota/quota_tree.c:647 [inline]
 qtree_read_dquot+0x13f/0x650 fs/quota/quota_tree.c:667
 v2_read_dquot+0xbe/0x100 fs/quota/quota_v2.c:333
 dquot_acquire+0x188/0x680 fs/quota/dquot.c:463
 ext4_acquire_dquot+0x2eb/0x4a0 fs/ext4/super.c:6193
 dqget+0x762/0xe90 fs/quota/dquot.c:986
 __dquot_initialize+0x2d9/0xea0 fs/quota/dquot.c:1515
 ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
 ext4_orphan_cleanup+0x9d9/0x1240 fs/ext4/orphan.c:474
 ext4_fill_super+0x98de/0xa110 fs/ext4/super.c:4975
 mount_bdev+0x2c9/0x3f0 fs/super.c:1400
 legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x2ba/0xb40 fs/namespace.c:3012
 do_mount fs/namespace.c:3355 [inline]
 __do_sys_mount fs/namespace.c:3563 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3540
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fdf82700fba
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:00007fdf80576e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fdf80576ef0 RCX: 00007fdf82700fba
RDX: 0000000020000000 RSI: 0000000020000500 RDI: 00007fdf80576eb0
RBP: 0000000020000000 R08: 00007fdf80576ef0 R09: 000000000001c916
R10: 000000000001c916 R11: 0000000000000246 R12: 0000000020000500
R13: 00007fdf80576eb0 R14: 00000000000004d8 R15: 0000000020000100
 </TASK>
EXT4-fs (loop2): ext4_process_orphan: truncating inode 12 to 4096 bytes
EXT4-fs (loop2): 1 truncate cleaned up
EXT4-fs (loop2): mounted filesystem without journal. Opts: nobarrier,noblock_validity,nombcache,norecovery,acl,resgid=0x000000000000ee01,norecovery,noauto_da_alloc,resgid=0x000000000000ee002,errors=continue. Quota mode: writeback.