syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:8/4510 is trying to acquire lock:
ffff888070768100 (&rl->lock){++++}-{3:3}, at: ntfs_read_block fs/ntfs/aops.c:248 [inline]
ffff888070768100 (&rl->lock){++++}-{3:3}, at: ntfs_read_folio+0x1463/0x29c0 fs/ntfs/aops.c:436

but task is already holding lock:
ffff8880548d5410 (&ni->mrec_lock){+.+.}-{3:3}, at: map_mft_record+0x4c/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+0x12d/0xaf0 kernel/locking/mutex.c:747
       map_mft_record+0x4c/0x650 fs/ntfs/mft.c:154
       ntfs_attr_extend_allocation+0x528/0x4360 fs/ntfs/attrib.c:2002
       ntfs_prepare_file_for_write fs/ntfs/file.c:391 [inline]
       ntfs_file_write_iter+0x369/0x1a70 fs/ntfs/file.c:1915
       call_write_iter include/linux/fs.h:2265 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x4b1/0xa30 fs/read_write.c:584
       ksys_write+0x14c/0x250 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&rl->lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       ntfs_read_block fs/ntfs/aops.c:248 [inline]
       ntfs_read_folio+0x1463/0x29c0 fs/ntfs/aops.c:436
       filemap_read_folio+0x16b/0x770 mm/filemap.c:2490
       do_read_cache_folio+0x2a0/0x760 mm/filemap.c:3659
       do_read_cache_page+0x32/0x220 mm/filemap.c:3701
       read_mapping_page include/linux/pagemap.h:793 [inline]
       ntfs_map_page fs/ntfs/aops.h:75 [inline]
       ntfs_sync_mft_mirror+0x24f/0x1ad0 fs/ntfs/mft.c:480
       write_mft_record_nolock+0x1188/0x1900 fs/ntfs/mft.c:787
       write_mft_record+0x136/0x300 fs/ntfs/mft.h:95
       __ntfs_write_inode+0x724/0xbf0 fs/ntfs/inode.c:3050
       write_inode fs/fs-writeback.c:1470 [inline]
       __writeback_single_inode+0x75b/0x1160 fs/fs-writeback.c:1687
       writeback_sb_inodes+0xb30/0x1850 fs/fs-writeback.c:1913
       wb_writeback+0x482/0xd50 fs/fs-writeback.c:2087
       wb_do_writeback fs/fs-writeback.c:2230 [inline]
       wb_workfn+0x423/0xee0 fs/fs-writeback.c:2270
       process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
       worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
       kthread+0x29d/0x330 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

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);
  lock(&rl->lock);

 *** DEADLOCK ***

3 locks held by kworker/u4:8/4510:
 #0: ffff88801ba6d938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc90003637d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #2: ffff8880548d5410 (&ni->mrec_lock){+.+.}-{3:3}, at: map_mft_record+0x4c/0x650 fs/ntfs/mft.c:154

stack backtrace:
CPU: 1 PID: 4510 Comm: kworker/u4:8 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: writeback wb_workfn (flush-7:2)
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
 ntfs_read_block fs/ntfs/aops.c:248 [inline]
 ntfs_read_folio+0x1463/0x29c0 fs/ntfs/aops.c:436
 filemap_read_folio+0x16b/0x770 mm/filemap.c:2490
 do_read_cache_folio+0x2a0/0x760 mm/filemap.c:3659
 do_read_cache_page+0x32/0x220 mm/filemap.c:3701
 read_mapping_page include/linux/pagemap.h:793 [inline]
 ntfs_map_page fs/ntfs/aops.h:75 [inline]
 ntfs_sync_mft_mirror+0x24f/0x1ad0 fs/ntfs/mft.c:480
 write_mft_record_nolock+0x1188/0x1900 fs/ntfs/mft.c:787
 write_mft_record+0x136/0x300 fs/ntfs/mft.h:95
 __ntfs_write_inode+0x724/0xbf0 fs/ntfs/inode.c:3050
 write_inode fs/fs-writeback.c:1470 [inline]
 __writeback_single_inode+0x75b/0x1160 fs/fs-writeback.c:1687
 writeback_sb_inodes+0xb30/0x1850 fs/fs-writeback.c:1913
 wb_writeback+0x482/0xd50 fs/fs-writeback.c:2087
 wb_do_writeback fs/fs-writeback.c:2230 [inline]
 wb_workfn+0x423/0xee0 fs/fs-writeback.c:2270
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>