syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:12/3512 is trying to acquire lock:
ffff88805a1f4b40 (&rl->lock){++++}-{3:3}, at: ntfs_read_block fs/ntfs/aops.c:248 [inline]
ffff88805a1f4b40 (&rl->lock){++++}-{3:3}, at: ntfs_read_folio+0x144d/0x2980 fs/ntfs/aops.c:436

but task is already holding lock:
ffff88805a1f7510 (&ni->mrec_lock){+.+.}-{3:3}, at: map_mft_record+0x50/0x650 fs/ntfs/mft.c:154

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->mrec_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       map_mft_record+0x50/0x650 fs/ntfs/mft.c:154
       ntfs_truncate+0x28a/0x28a0 fs/ntfs/inode.c:2383
       ntfs_truncate_vfs fs/ntfs/inode.c:2863 [inline]
       ntfs_setattr+0x34a/0x430 fs/ntfs/inode.c:2915
       notify_change+0xb0d/0xe10 fs/attr.c:499
       do_truncate+0x19b/0x220 fs/open.c:66
       vfs_truncate+0x266/0x300 fs/open.c:112
       do_sys_truncate+0xe0/0x1a0 fs/open.c:135
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&rl->lock){++++}-{3:3}:
       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+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ntfs_read_block fs/ntfs/aops.c:248 [inline]
       ntfs_read_folio+0x144d/0x2980 fs/ntfs/aops.c:436
       filemap_read_folio+0x167/0x760 mm/filemap.c:2420
       do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3804
       do_read_cache_page+0x32/0x250 mm/filemap.c:3870
       read_mapping_page include/linux/pagemap.h:892 [inline]
       ntfs_map_page fs/ntfs/aops.h:75 [inline]
       ntfs_sync_mft_mirror+0x236/0x1aa0 fs/ntfs/mft.c:480
       write_mft_record_nolock+0x116f/0x18c0 fs/ntfs/mft.c:787
       write_mft_record+0x136/0x300 fs/ntfs/mft.h:95
       __ntfs_write_inode+0x731/0xc00 fs/ntfs/inode.c:3051
       write_inode fs/fs-writeback.c:1483 [inline]
       __writeback_single_inode+0x705/0xee0 fs/fs-writeback.c:1700
       writeback_sb_inodes+0x77c/0xef0 fs/fs-writeback.c:1926
       wb_writeback+0x450/0xba0 fs/fs-writeback.c:2105
       wb_do_writeback fs/fs-writeback.c:2252 [inline]
       wb_workfn+0x3ff/0xe20 fs/fs-writeback.c:2292
       process_one_work kernel/workqueue.c:2634 [inline]
       process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
       worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
       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:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ni->mrec_lock);
                               lock(&rl->lock);
                               lock(&ni->mrec_lock);
  rlock(&rl->lock);

 *** DEADLOCK ***

3 locks held by kworker/u4:12/3512:
 #0: ffff88801a27e938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88801a27e938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000d3cfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000d3cfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff88805a1f7510 (&ni->mrec_lock){+.+.}-{3:3}, at: map_mft_record+0x50/0x650 fs/ntfs/mft.c:154

stack backtrace:
CPU: 1 PID: 3512 Comm: kworker/u4:12 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: writeback wb_workfn (flush-7:3)
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 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+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
 ntfs_read_block fs/ntfs/aops.c:248 [inline]
 ntfs_read_folio+0x144d/0x2980 fs/ntfs/aops.c:436
 filemap_read_folio+0x167/0x760 mm/filemap.c:2420
 do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3804
 do_read_cache_page+0x32/0x250 mm/filemap.c:3870
 read_mapping_page include/linux/pagemap.h:892 [inline]
 ntfs_map_page fs/ntfs/aops.h:75 [inline]
 ntfs_sync_mft_mirror+0x236/0x1aa0 fs/ntfs/mft.c:480
 write_mft_record_nolock+0x116f/0x18c0 fs/ntfs/mft.c:787
 write_mft_record+0x136/0x300 fs/ntfs/mft.h:95
 __ntfs_write_inode+0x731/0xc00 fs/ntfs/inode.c:3051
 write_inode fs/fs-writeback.c:1483 [inline]
 __writeback_single_inode+0x705/0xee0 fs/fs-writeback.c:1700
 writeback_sb_inodes+0x77c/0xef0 fs/fs-writeback.c:1926
 wb_writeback+0x450/0xba0 fs/fs-writeback.c:2105
 wb_do_writeback fs/fs-writeback.c:2252 [inline]
 wb_workfn+0x3ff/0xe20 fs/fs-writeback.c:2292
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 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>