warning: checkpointing journal with EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT can be slow
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/4382 is trying to acquire lock:
ffff8880264f83f0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:803 [inline]
ffff8880264f83f0 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_bmap+0x4f/0x3f0 fs/ext4/inode.c:3166

but task is already holding lock:
ffff88814d3c83f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x317/0xcd0 fs/jbd2/journal.c:2499

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       mutex_lock_io_nested+0x43/0x60 kernel/locking/mutex.c:777
       jbd2_journal_flush+0x285/0xcd0 fs/jbd2/journal.c:2489
       ext4_ioctl_checkpoint fs/ext4/ioctl.c:856 [inline]
       __ext4_ioctl fs/ext4/ioctl.c:1282 [inline]
       ext4_ioctl+0x31f7/0x3840 fs/ext4/ioctl.c:1291
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
       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

-> #2 (&journal->j_barrier){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       jbd2_journal_lock_updates+0x2ce/0x390 fs/jbd2/transaction.c:905
       ext4_change_inode_journal_flag+0x18e/0x710 fs/ext4/inode.c:6135
       ext4_ioctl_setflags fs/ext4/ioctl.c:448 [inline]
       ext4_fileattr_set+0xe61/0x1750 fs/ext4/ioctl.c:772
       vfs_fileattr_set+0x859/0xb10 fs/ioctl.c:700
       ioctl_setflags fs/ioctl.c:732 [inline]
       do_vfs_ioctl+0x1881/0x1f40 fs/ioctl.c:843
       __do_sys_ioctl fs/ioctl.c:872 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:860
       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 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       percpu_down_write+0x52/0x2f0 kernel/locking/percpu-rwsem.c:217
       ext4_ind_migrate+0x247/0x8e0 fs/ext4/migrate.c:625
       ext4_ioctl_setflags fs/ext4/ioctl.c:457 [inline]
       ext4_fileattr_set+0xf53/0x1750 fs/ext4/ioctl.c:772
       vfs_fileattr_set+0x859/0xb10 fs/ioctl.c:700
       ioctl_setflags fs/ioctl.c:732 [inline]
       do_vfs_ioctl+0x1881/0x1f40 fs/ioctl.c:843
       __do_sys_ioctl fs/ioctl.c:872 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:860
       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 (&sb->s_type->i_mutex_key#9){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3120 [inline]
       check_prevs_add kernel/locking/lockdep.c:3239 [inline]
       validate_chain kernel/locking/lockdep.c:3855 [inline]
       __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
       lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       inode_lock_shared include/linux/fs.h:803 [inline]
       ext4_bmap+0x4f/0x3f0 fs/ext4/inode.c:3166
       bmap+0xa2/0xd0 fs/inode.c:1820
       jbd2_journal_bmap fs/jbd2/journal.c:981 [inline]
       __jbd2_journal_erase fs/jbd2/journal.c:1795 [inline]
       jbd2_journal_flush+0x7e0/0xcd0 fs/jbd2/journal.c:2517
       ext4_ioctl_checkpoint fs/ext4/ioctl.c:856 [inline]
       __ext4_ioctl fs/ext4/ioctl.c:1282 [inline]
       ext4_ioctl+0x31f7/0x3840 fs/ext4/ioctl.c:1291
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
       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:
  &sb->s_type->i_mutex_key#9 --> &journal->j_barrier --> &journal->j_checkpoint_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&journal->j_checkpoint_mutex);
                               lock(&journal->j_barrier);
                               lock(&journal->j_checkpoint_mutex);
  rlock(&sb->s_type->i_mutex_key#9);

 *** DEADLOCK ***

2 locks held by syz.0.17/4382:
 #0: ffff88814d3c8170 (&journal->j_barrier){+.+.}-{3:3}, at: jbd2_journal_lock_updates+0x2ce/0x390 fs/jbd2/transaction.c:905
 #1: ffff88814d3c83f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x317/0xcd0 fs/jbd2/journal.c:2499

stack backtrace:
CPU: 1 PID: 4382 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x400 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3120 [inline]
 check_prevs_add kernel/locking/lockdep.c:3239 [inline]
 validate_chain kernel/locking/lockdep.c:3855 [inline]
 __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
 lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
 down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
 inode_lock_shared include/linux/fs.h:803 [inline]
 ext4_bmap+0x4f/0x3f0 fs/ext4/inode.c:3166
 bmap+0xa2/0xd0 fs/inode.c:1820
 jbd2_journal_bmap fs/jbd2/journal.c:981 [inline]
 __jbd2_journal_erase fs/jbd2/journal.c:1795 [inline]
 jbd2_journal_flush+0x7e0/0xcd0 fs/jbd2/journal.c:2517
 ext4_ioctl_checkpoint fs/ext4/ioctl.c:856 [inline]
 __ext4_ioctl fs/ext4/ioctl.c:1282 [inline]
 ext4_ioctl+0x31f7/0x3840 fs/ext4/ioctl.c:1291
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 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: 0033:0x7f465d50b559
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:00007fff4d6987c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f465d792fa0 RCX: 00007f465d50b559
RDX: 00002000000001c0 RSI: 000000004004662b RDI: 0000000000000004
RBP: 00007f465d5a2ab8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f465d792fac R14: 00007f465d792fa0 R15: 00007f465d792fa0
 </TASK>