syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.8.692/10767 is trying to acquire lock:
ffff88801afde090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff88801786baa0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
ffff88801786baa0 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x168/0x400 mm/util.c:554

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc6/0x120 mm/memory.c:5968
       reiserfs_ioctl+0x143/0x2d0 fs/reiserfs/ioctl.c:96
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
       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 (&sbi->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
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
       reiserfs_dirty_inode+0xf4/0x240 fs/reiserfs/super.c:704
       __mark_inode_dirty+0x2cc/0xca0 fs/fs-writeback.c:2465
       generic_update_time fs/inode.c:1981 [inline]
       inode_update_time fs/inode.c:1994 [inline]
       touch_atime+0x356/0x580 fs/inode.c:2065
       file_accessed include/linux/fs.h:2358 [inline]
       generic_file_mmap+0xc8/0x130 mm/filemap.c:3724
       call_mmap include/linux/fs.h:2023 [inline]
       mmap_file mm/internal.h:98 [inline]
       __mmap_region mm/mmap.c:2790 [inline]
       mmap_region+0xfa5/0x2020 mm/mmap.c:2941
       do_mmap+0x92f/0x10a0 mm/mmap.c:1385
       vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
       ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1431
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_lock);
                               lock(&sbi->lock);
                               lock(&mm->mmap_lock);
  lock(&sbi->lock);

 *** DEADLOCK ***

2 locks held by syz.8.692/10767:
 #0: ffff88801786baa0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
 #0: ffff88801786baa0 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x168/0x400 mm/util.c:554
 #1: ffff88802623c418 (sb_writers#29){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2358 [inline]
 #1: ffff88802623c418 (sb_writers#29){.+.+}-{0:0}, at: generic_file_mmap+0xc8/0x130 mm/filemap.c:3724

stack backtrace:
CPU: 1 PID: 10767 Comm: syz.8.692 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
 reiserfs_dirty_inode+0xf4/0x240 fs/reiserfs/super.c:704
 __mark_inode_dirty+0x2cc/0xca0 fs/fs-writeback.c:2465
 generic_update_time fs/inode.c:1981 [inline]
 inode_update_time fs/inode.c:1994 [inline]
 touch_atime+0x356/0x580 fs/inode.c:2065
 file_accessed include/linux/fs.h:2358 [inline]
 generic_file_mmap+0xc8/0x130 mm/filemap.c:3724
 call_mmap include/linux/fs.h:2023 [inline]
 mmap_file mm/internal.h:98 [inline]
 __mmap_region mm/mmap.c:2790 [inline]
 mmap_region+0xfa5/0x2020 mm/mmap.c:2941
 do_mmap+0x92f/0x10a0 mm/mmap.c:1385
 vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
 ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1431
 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
RIP: 0033:0x7f45f358f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f45f43ef038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f45f37e6090 RCX: 00007f45f358f749
RDX: 0000000000000001 RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f45f3613f91 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f45f37e6128 R14: 00007f45f37e6090 R15: 00007fff66daedb8
 </TASK>