======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.537/6584 is trying to acquire lock:
ffff888027add090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x75/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1302 [inline]
ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1481 [inline]
ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1558 [inline]
ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind+0x4c6/0x810 mm/mempolicy.c:1554

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc2/0x120 mm/memory.c:5850
       reiserfs_ioctl+0x13b/0x330 fs/reiserfs/ioctl.c:96
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
       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 (&sbi->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
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12d/0xaf0 kernel/locking/mutex.c:747
       reiserfs_write_lock+0x75/0xd0 fs/reiserfs/lock.c:27
       map_block_for_writepage fs/reiserfs/inode.c:2388 [inline]
       reiserfs_write_full_page fs/reiserfs/inode.c:2585 [inline]
       reiserfs_writepage+0xa29/0x3af0 fs/reiserfs/inode.c:2737
       writeout mm/migrate.c:888 [inline]
       fallback_migrate_folio mm/migrate.c:912 [inline]
       move_to_new_folio+0x636/0xe00 mm/migrate.c:961
       __migrate_folio_move mm/migrate.c:1199 [inline]
       migrate_folio_move mm/migrate.c:1297 [inline]
       migrate_pages_batch mm/migrate.c:1639 [inline]
       migrate_pages+0x36b3/0x55e0 mm/migrate.c:1843
       do_mbind mm/mempolicy.c:1334 [inline]
       kernel_mbind mm/mempolicy.c:1481 [inline]
       __do_sys_mbind mm/mempolicy.c:1558 [inline]
       __se_sys_mbind+0x64f/0x810 mm/mempolicy.c:1554
       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

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 ***

1 lock held by syz.0.537/6584:
 #0: ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 #0: ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1302 [inline]
 #0: ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1481 [inline]
 #0: ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1558 [inline]
 #0: ffff8880252ce2d8 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind+0x4c6/0x810 mm/mempolicy.c:1554

stack backtrace:
CPU: 0 PID: 6584 Comm: syz.0.537 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12d/0xaf0 kernel/locking/mutex.c:747
 reiserfs_write_lock+0x75/0xd0 fs/reiserfs/lock.c:27
 map_block_for_writepage fs/reiserfs/inode.c:2388 [inline]
 reiserfs_write_full_page fs/reiserfs/inode.c:2585 [inline]
 reiserfs_writepage+0xa29/0x3af0 fs/reiserfs/inode.c:2737
 writeout mm/migrate.c:888 [inline]
 fallback_migrate_folio mm/migrate.c:912 [inline]
 move_to_new_folio+0x636/0xe00 mm/migrate.c:961
 __migrate_folio_move mm/migrate.c:1199 [inline]
 migrate_folio_move mm/migrate.c:1297 [inline]
 migrate_pages_batch mm/migrate.c:1639 [inline]
 migrate_pages+0x36b3/0x55e0 mm/migrate.c:1843
 do_mbind mm/mempolicy.c:1334 [inline]
 kernel_mbind mm/mempolicy.c:1481 [inline]
 __do_sys_mbind mm/mempolicy.c:1558 [inline]
 __se_sys_mbind+0x64f/0x810 mm/mempolicy.c:1554
 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
RIP: 0033:0x7f5d1fd9c819
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:00007f5d20cad028 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
RAX: ffffffffffffffda RBX: 00007f5d20015fa0 RCX: 00007f5d1fd9c819
RDX: 0000000000004005 RSI: 0000000000004000 RDI: 0000200000000000
RBP: 00007f5d1fe32c91 R08: 0000000000000006 R09: 0000000000000002
R10: 0000200000000c00 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5d20016038 R14: 00007f5d20015fa0 R15: 00007ffecdef0e08
 </TASK>