syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:2/34 is trying to acquire lock:
ffff88814dec8990 (jbd2_handle){++++}-{0:0}, at: wait_transaction_locked+0x1aa/0x270 fs/jbd2/transaction.c:155

but task is already holding lock:
ffff88814dec6c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1768 [inline]
ffff88814dec6c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2808

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
       ext4_writepages_down_read fs/ext4/ext4.h:1768 [inline]
       ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2808
       do_writepages+0x3b3/0x630 mm/page-writeback.c:2575
       __writeback_single_inode+0x153/0xec0 fs/fs-writeback.c:1635
       writeback_single_inode+0x21f/0x760 fs/fs-writeback.c:1756
       write_inode_now+0x183/0x210 fs/fs-writeback.c:2808
       iput_final fs/inode.c:1807 [inline]
       iput+0x5ae/0x920 fs/inode.c:1846
       ext4_xattr_block_set+0x249e/0x32b0 fs/ext4/xattr.c:2146
       ext4_xattr_move_to_block fs/ext4/xattr.c:2664 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2739 [inline]
       ext4_expand_extra_isize_ea+0x12c5/0x1e80 fs/ext4/xattr.c:2827
       __ext4_expand_extra_isize+0x306/0x400 fs/ext4/inode.c:5990
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6033 [inline]
       __ext4_mark_inode_dirty+0x45d/0x6e0 fs/ext4/inode.c:6111
       ext4_evict_inode+0x7f3/0xea0 fs/ext4/inode.c:254
       evict+0x4ca/0x8d0 fs/inode.c:705
       ext4_orphan_cleanup+0xbec/0x1420 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5621 [inline]
       ext4_fill_super+0x5eea/0x67b0 fs/ext4/super.c:5744
       get_tree_bdev+0x3f3/0x520 fs/super.c:1591
       vfs_get_tree+0x8c/0x280 fs/super.c:1764
       do_new_mount+0x24b/0xa40 fs/namespace.c:3386
       do_mount fs/namespace.c:3726 [inline]
       __do_sys_mount fs/namespace.c:3935 [inline]
       __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&ei->xattr_sem){++++}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ext4_setattr+0x86b/0x1dc0 fs/ext4/inode.c:5501
       notify_change+0xb0d/0xe10 fs/attr.c:499
       chown_common+0x413/0x5d0 fs/open.c:783
       do_fchownat+0x14b/0x240 fs/open.c:814
       __do_sys_chown fs/open.c:834 [inline]
       __se_sys_chown fs/open.c:832 [inline]
       __x64_sys_chown+0x82/0x90 fs/open.c:832
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (jbd2_handle){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       wait_transaction_locked+0x1c3/0x270 fs/jbd2/transaction.c:155
       add_transaction_credits fs/jbd2/transaction.c:226 [inline]
       start_this_handle+0x7e8/0x21c0 fs/jbd2/transaction.c:407
       jbd2__journal_start+0x2bb/0x5b0 fs/jbd2/transaction.c:505
       __ext4_journal_start_sb+0x203/0x560 fs/ext4/ext4_jbd2.c:112
       __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
       ext4_do_writepages+0xfb7/0x3990 fs/ext4/inode.c:2703
       ext4_writepages+0x1dd/0x350 fs/ext4/inode.c:2809
       do_writepages+0x3b3/0x630 mm/page-writeback.c:2575
       __writeback_single_inode+0x153/0xec0 fs/fs-writeback.c:1635
       writeback_sb_inodes+0x7cd/0xf50 fs/fs-writeback.c:1926
       __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:1997
       wb_writeback+0x47e/0xbf0 fs/fs-writeback.c:2107
       wb_check_old_data_flush fs/fs-writeback.c:2211 [inline]
       wb_do_writeback fs/fs-writeback.c:2264 [inline]
       wb_workfn+0xad7/0xe60 fs/fs-writeback.c:2292
       process_one_work kernel/workqueue.c:2653 [inline]
       process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730
       worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811
       kthread+0x2fa/0x390 kernel/kthread.c:388
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

other info that might help us debug this:

Chain exists of:
  jbd2_handle --> &ei->xattr_sem --> &sbi->s_writepages_rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&sbi->s_writepages_rwsem);
                               lock(&ei->xattr_sem);
                               lock(&sbi->s_writepages_rwsem);
  lock(jbd2_handle);

 *** DEADLOCK ***

4 locks held by kworker/u4:2/34:
 #0: ffff88801ce77538 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff88801ce77538 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc90000aafd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc90000aafd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #2: ffff88814dec40e0 (&type->s_umount_key#32){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607
 #3: ffff88814dec6c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1768 [inline]
 #3: ffff88814dec6c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2808

stack backtrace:
CPU: 1 PID: 34 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 wait_transaction_locked+0x1c3/0x270 fs/jbd2/transaction.c:155
 add_transaction_credits fs/jbd2/transaction.c:226 [inline]
 start_this_handle+0x7e8/0x21c0 fs/jbd2/transaction.c:407
 jbd2__journal_start+0x2bb/0x5b0 fs/jbd2/transaction.c:505
 __ext4_journal_start_sb+0x203/0x560 fs/ext4/ext4_jbd2.c:112
 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
 ext4_do_writepages+0xfb7/0x3990 fs/ext4/inode.c:2703
 ext4_writepages+0x1dd/0x350 fs/ext4/inode.c:2809
 do_writepages+0x3b3/0x630 mm/page-writeback.c:2575
 __writeback_single_inode+0x153/0xec0 fs/fs-writeback.c:1635
 writeback_sb_inodes+0x7cd/0xf50 fs/fs-writeback.c:1926
 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:1997
 wb_writeback+0x47e/0xbf0 fs/fs-writeback.c:2107
 wb_check_old_data_flush fs/fs-writeback.c:2211 [inline]
 wb_do_writeback fs/fs-writeback.c:2264 [inline]
 wb_workfn+0xad7/0xe60 fs/fs-writeback.c:2292
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>