syzbot

EXT4-fs (loop5): mounted filesystem 00000000-0000-0000-0000-000000000000 without journal. Quota mode: writeback.
======================================================
WARNING: possible circular locking dependency detected
6.3.0-rc3-syzkaller-00026-gfff5a5e7f528 #0 Not tainted
------------------------------------------------------
syz-executor.5/23700 is trying to acquire lock:
ffff8880360ea0a0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x980/0x1cf0 fs/ext4/inode.c:644

but task is already holding lock:
ffff888033c5e208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_write_dquot+0x9f/0x190 fs/quota/quota_v2.c:354

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+0x1e1/0x520 kernel/locking/lockdep.c:5669
       down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
       v2_read_dquot+0x4e/0x110 fs/quota/quota_v2.c:332
       dquot_acquire+0x18c/0x680 fs/quota/dquot.c:435
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6770
       dqget+0x98f/0xdb0 fs/quota/dquot.c:914
       __dquot_initialize+0x2dd/0xe20 fs/quota/dquot.c:1492
       ext4_create+0xb5/0x550 fs/ext4/namei.c:2801
       lookup_open fs/namei.c:3416 [inline]
       open_last_lookups fs/namei.c:3484 [inline]
       path_openat+0x13df/0x3170 fs/namei.c:3712
       do_filp_open+0x234/0x490 fs/namei.c:3742
       do_sys_openat2+0x13f/0x500 fs/open.c:1348
       do_sys_open fs/open.c:1364 [inline]
       __do_sys_openat fs/open.c:1380 [inline]
       __se_sys_openat fs/open.c:1375 [inline]
       __x64_sys_openat+0x247/0x290 fs/open.c:1375
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       lock_acquire+0x1e1/0x520 kernel/locking/lockdep.c:5669
       __mutex_lock_common+0x1d8/0x2530 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
       dquot_commit+0x5b/0x520 fs/quota/dquot.c:479
       ext4_write_dquot+0x1f2/0x2c0 fs/ext4/super.c:6754
       mark_dquot_dirty fs/quota/dquot.c:346 [inline]
       mark_all_dquot_dirty fs/quota/dquot.c:384 [inline]
       __dquot_alloc_space+0x54c/0xf50 fs/quota/dquot.c:1722
       dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline]
       dquot_alloc_space include/linux/quotaops.h:313 [inline]
       dquot_alloc_block include/linux/quotaops.h:337 [inline]
       ext4_mb_new_blocks+0x111a/0x45f0 fs/ext4/mballoc.c:5571
       ext4_ext_map_blocks+0x1973/0x7210 fs/ext4/extents.c:4286
       ext4_map_blocks+0xa4c/0x1cf0 fs/ext4/inode.c:651
       ext4_getblk+0x1ef/0x7c0 fs/ext4/inode.c:863
       ext4_bread+0x2e/0x180 fs/ext4/inode.c:919
       ext4_append+0x323/0x5c0 fs/ext4/namei.c:83
       ext4_init_new_dir+0x33e/0xa20 fs/ext4/namei.c:2955
       ext4_mkdir+0x4f6/0xce0 fs/ext4/namei.c:3001
       vfs_mkdir+0x29d/0x450 fs/namei.c:4038
       do_mkdirat+0x264/0x520 fs/namei.c:4061
       __do_sys_mkdirat fs/namei.c:4076 [inline]
       __se_sys_mkdirat fs/namei.c:4074 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4074
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&ei->i_data_sem/2){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3098 [inline]
       check_prevs_add kernel/locking/lockdep.c:3217 [inline]
       validate_chain+0x166b/0x58e0 kernel/locking/lockdep.c:3832
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
       lock_acquire+0x1e1/0x520 kernel/locking/lockdep.c:5669
       down_write+0x3a/0x50 kernel/locking/rwsem.c:1573
       ext4_map_blocks+0x980/0x1cf0 fs/ext4/inode.c:644
       ext4_getblk+0x1ef/0x7c0 fs/ext4/inode.c:863
       ext4_bread+0x2e/0x180 fs/ext4/inode.c:919
       ext4_quota_write+0x222/0x580 fs/ext4/super.c:7135
       write_blk fs/quota/quota_tree.c:64 [inline]
       find_free_dqentry fs/quota/quota_tree.c:312 [inline]
       do_insert_tree+0xe07/0x1a60 fs/quota/quota_tree.c:373
       do_insert_tree+0x70f/0x1a60 fs/quota/quota_tree.c:375
       do_insert_tree+0x70f/0x1a60 fs/quota/quota_tree.c:375
       do_insert_tree+0x70f/0x1a60 fs/quota/quota_tree.c:375
       dq_insert_tree fs/quota/quota_tree.c:401 [inline]
       qtree_write_dquot+0x3bd/0x530 fs/quota/quota_tree.c:420
       v2_write_dquot+0x120/0x190 fs/quota/quota_v2.c:358
       dquot_acquire+0x351/0x680 fs/quota/dquot.c:444
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6770
       dqget+0x98f/0xdb0 fs/quota/dquot.c:914
       __dquot_initialize+0x462/0xe20 fs/quota/dquot.c:1492
       ext4_create+0xb5/0x550 fs/ext4/namei.c:2801
       lookup_open fs/namei.c:3416 [inline]
       open_last_lookups fs/namei.c:3484 [inline]
       path_openat+0x13df/0x3170 fs/namei.c:3712
       do_filp_open+0x234/0x490 fs/namei.c:3742
       do_sys_openat2+0x13f/0x500 fs/open.c:1348
       do_sys_open fs/open.c:1364 [inline]
       __do_sys_open fs/open.c:1372 [inline]
       __se_sys_open fs/open.c:1368 [inline]
       __x64_sys_open+0x225/0x270 fs/open.c:1368
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

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 ***

4 locks held by syz-executor.5/23700:
 #0: ffff888033c5e460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:394
 #1: ffff8880360ec030 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff8880360ec030 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: open_last_lookups fs/namei.c:3481 [inline]
 #1: ffff8880360ec030 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: path_openat+0x7ba/0x3170 fs/namei.c:3712
 #2: ffff88803c40d768 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_acquire+0x68/0x680 fs/quota/dquot.c:432
 #3: ffff888033c5e208 (&s->s_dquot.dqio_sem){++++}-{3:3}, at: v2_write_dquot+0x9f/0x190 fs/quota/quota_v2.c:354

stack backtrace:
CPU: 1 PID: 23700 Comm: syz-executor.5 Not tainted 6.3.0-rc3-syzkaller-00026-gfff5a5e7f528 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2fe/0x3b0 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3098 [inline]
 check_prevs_add kernel/locking/lockdep.c:3217 [inline]
 validate_chain+0x166b/0x58e0 kernel/locking/lockdep.c:3832
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
 lock_acquire+0x1e1/0x520 kernel/locking/lockdep.c:5669
 down_write+0x3a/0x50 kernel/locking/rwsem.c:1573
 ext4_map_blocks+0x980/0x1cf0 fs/ext4/inode.c:644
 ext4_getblk+0x1ef/0x7c0 fs/ext4/inode.c:863
 ext4_bread+0x2e/0x180 fs/ext4/inode.c:919
 ext4_quota_write+0x222/0x580 fs/ext4/super.c:7135
 write_blk fs/quota/quota_tree.c:64 [inline]
 find_free_dqentry fs/quota/quota_tree.c:312 [inline]
 do_insert_tree+0xe07/0x1a60 fs/quota/quota_tree.c:373
 do_insert_tree+0x70f/0x1a60 fs/quota/quota_tree.c:375
 do_insert_tree+0x70f/0x1a60 fs/quota/quota_tree.c:375
 do_insert_tree+0x70f/0x1a60 fs/quota/quota_tree.c:375
 dq_insert_tree fs/quota/quota_tree.c:401 [inline]
 qtree_write_dquot+0x3bd/0x530 fs/quota/quota_tree.c:420
 v2_write_dquot+0x120/0x190 fs/quota/quota_v2.c:358
 dquot_acquire+0x351/0x680 fs/quota/dquot.c:444
 ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6770
 dqget+0x98f/0xdb0 fs/quota/dquot.c:914
 __dquot_initialize+0x462/0xe20 fs/quota/dquot.c:1492
 ext4_create+0xb5/0x550 fs/ext4/namei.c:2801
 lookup_open fs/namei.c:3416 [inline]
 open_last_lookups fs/namei.c:3484 [inline]
 path_openat+0x13df/0x3170 fs/namei.c:3712
 do_filp_open+0x234/0x490 fs/namei.c:3742
 do_sys_openat2+0x13f/0x500 fs/open.c:1348
 do_sys_open fs/open.c:1364 [inline]
 __do_sys_open fs/open.c:1372 [inline]
 __se_sys_open fs/open.c:1368 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1368
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc0eac8c0f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc0eba18168 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fc0eadabf80 RCX: 00007fc0eac8c0f9
RDX: 0000000000000000 RSI: 000000000014937e RDI: 0000000020000180
RBP: 00007fc0eace7b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff8357c10f R14: 00007fc0eba18300 R15: 0000000000022000
 </TASK>