syzbot

ocfs2: Mounting device (7,4) on (node local, slot 0) with writeback data mode.
======================================================
WARNING: possible circular locking dependency detected
6.6.102-syzkaller #0 Not tainted
------------------------------------------------------
syz.4.1187/11094 is trying to acquire lock:
ffff88802d0f6a20 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0xaa/0x120 mm/memory.c:5946

but task is already holding lock:
ffff8880787eb120 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_fiemap+0x2ad/0xc80 fs/ocfs2/extent_map.c:755

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       ocfs2_page_mkwrite+0x2d0/0xd10 fs/ocfs2/mmap.c:142
       do_page_mkwrite+0x153/0x3e0 mm/memory.c:2950
       wp_page_shared mm/memory.c:3310 [inline]
       do_wp_page+0xe5e/0x3630 mm/memory.c:3395
       handle_pte_fault mm/memory.c:5041 [inline]
       __handle_mm_fault mm/memory.c:5166 [inline]
       handle_mm_fault+0x12d4/0x4920 mm/memory.c:5331
       do_user_addr_fault+0x738/0x12e0 arch/x86/mm/fault.c:1373
       handle_page_fault arch/x86/mm/fault.c:1465 [inline]
       exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
       __put_user_4+0x11/0x20 arch/x86/lib/putuser.S:87
       __sys_socketpair+0xb8/0x550 net/socket.c:1765
       __do_sys_socketpair net/socket.c:1831 [inline]
       __se_sys_socketpair net/socket.c:1828 [inline]
       __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
       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

-> #1 (sb_pagefaults#3){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1633 [inline]
       sb_start_pagefault include/linux/fs.h:1737 [inline]
       ocfs2_page_mkwrite+0x18b/0xd10 fs/ocfs2/mmap.c:122
       do_page_mkwrite+0x153/0x3e0 mm/memory.c:2950
       wp_page_shared mm/memory.c:3310 [inline]
       do_wp_page+0xe5e/0x3630 mm/memory.c:3395
       handle_pte_fault mm/memory.c:5041 [inline]
       __handle_mm_fault mm/memory.c:5166 [inline]
       handle_mm_fault+0x12d4/0x4920 mm/memory.c:5331
       do_user_addr_fault+0x738/0x12e0 arch/x86/mm/fault.c:1373
       handle_page_fault arch/x86/mm/fault.c:1465 [inline]
       exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
       __put_user_4+0x11/0x20 arch/x86/lib/putuser.S:87
       __sys_socketpair+0xb8/0x550 net/socket.c:1765
       __do_sys_socketpair net/socket.c:1831 [inline]
       __se_sys_socketpair net/socket.c:1828 [inline]
       __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
       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 (&mm->mmap_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
       __might_fault+0xc6/0x120 mm/memory.c:5946
       _copy_to_user+0x2a/0xa0 lib/usercopy.c:36
       copy_to_user include/linux/uaccess.h:191 [inline]
       fiemap_fill_next_extent+0x1c1/0x390 fs/ioctl.c:145
       ocfs2_fiemap_inline fs/ocfs2/extent_map.c:725 [inline]
       ocfs2_fiemap+0x9d6/0xc80 fs/ocfs2/extent_map.c:762
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x140c/0x1bb0 fs/ioctl.c:811
       __do_sys_ioctl fs/ioctl.c:869 [inline]
       __se_sys_ioctl+0x83/0x170 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

other info that might help us debug this:

Chain exists of:
  &mm->mmap_lock --> sb_pagefaults#3 --> &ocfs2_file_ip_alloc_sem_key

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&ocfs2_file_ip_alloc_sem_key);
                               lock(sb_pagefaults#3);
                               lock(&ocfs2_file_ip_alloc_sem_key);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

1 lock held by syz.4.1187/11094:
 #0: ffff8880787eb120 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_fiemap+0x2ad/0xc80 fs/ocfs2/extent_map.c:755

stack backtrace:
CPU: 1 PID: 11094 Comm: syz.4.1187 Not tainted 6.6.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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
 __might_fault+0xc6/0x120 mm/memory.c:5946
 _copy_to_user+0x2a/0xa0 lib/usercopy.c:36
 copy_to_user include/linux/uaccess.h:191 [inline]
 fiemap_fill_next_extent+0x1c1/0x390 fs/ioctl.c:145
 ocfs2_fiemap_inline fs/ocfs2/extent_map.c:725 [inline]
 ocfs2_fiemap+0x9d6/0xc80 fs/ocfs2/extent_map.c:762
 ioctl_fiemap fs/ioctl.c:220 [inline]
 do_vfs_ioctl+0x140c/0x1bb0 fs/ioctl.c:811
 __do_sys_ioctl fs/ioctl.c:869 [inline]
 __se_sys_ioctl+0x83/0x170 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
RIP: 0033:0x7f243898ebe9
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:00007f2439739038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2438bb5fa0 RCX: 00007f243898ebe9
RDX: 0000200000000040 RSI: 00000000c020660b RDI: 0000000000000004
RBP: 00007f2438a11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2438bb6038 R14: 00007f2438bb5fa0 R15: 00007ffd93a70f88
 </TASK>