syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.5567/21324 is trying to acquire lock:
ffff888049220660 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}, at: ocfs2_page_mkwrite+0x2ff/0xc40 fs/ocfs2/mmap.c:142

but task is already holding lock:
ffff8880305c4520 (sb_pagefaults#6){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310 mm/memory.c:3361

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_pagefaults#6){.+.+}-{0:0}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
       percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
       __sb_start_write include/linux/fs.h:1799 [inline]
       sb_start_pagefault include/linux/fs.h:1964 [inline]
       ocfs2_page_mkwrite+0x1da/0xc40 fs/ocfs2/mmap.c:122
       do_page_mkwrite+0x14d/0x310 mm/memory.c:3361
       wp_page_shared mm/memory.c:3762 [inline]
       do_wp_page+0x268d/0x5800 mm/memory.c:3981
       handle_pte_fault mm/memory.c:6068 [inline]
       __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195
       handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
       do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387
       handle_page_fault arch/x86/mm/fault.c:1476 [inline]
       exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #1 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __might_fault+0xcc/0x130 mm/memory.c:6958
       _inline_copy_to_user include/linux/uaccess.h:192 [inline]
       _copy_to_user+0x2c/0xb0 lib/usercopy.c:26
       copy_to_user include/linux/uaccess.h:225 [inline]
       fiemap_fill_next_extent+0x1c0/0x390 fs/ioctl.c:145
       ocfs2_fiemap+0x888/0xc90 fs/ocfs2/extent_map.c:806
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x1173/0x1430 fs/ioctl.c:532
       __do_sys_ioctl fs/ioctl.c:596 [inline]
       __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
       ocfs2_page_mkwrite+0x2ff/0xc40 fs/ocfs2/mmap.c:142
       do_page_mkwrite+0x14d/0x310 mm/memory.c:3361
       wp_page_shared mm/memory.c:3762 [inline]
       do_wp_page+0x268d/0x5800 mm/memory.c:3981
       handle_pte_fault mm/memory.c:6068 [inline]
       __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195
       handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
       do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387
       handle_page_fault arch/x86/mm/fault.c:1476 [inline]
       exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

other info that might help us debug this:

Chain exists of:
  &ocfs2_file_ip_alloc_sem_key --> &mm->mmap_lock --> sb_pagefaults#6

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_pagefaults#6);
                               lock(&mm->mmap_lock);
                               lock(sb_pagefaults#6);
  lock(&ocfs2_file_ip_alloc_sem_key);

 *** DEADLOCK ***

2 locks held by syz.6.5567/21324:
 #0: ffff88806a4aace0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:472 [inline]
 #0: ffff88806a4aace0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:277 [inline]
 #0: ffff88806a4aace0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x32/0x300 mm/mmap_lock.c:337
 #1: ffff8880305c4520 (sb_pagefaults#6){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310 mm/memory.c:3361

stack backtrace:
CPU: 0 UID: 0 PID: 21324 Comm: syz.6.5567 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
 ocfs2_page_mkwrite+0x2ff/0xc40 fs/ocfs2/mmap.c:142
 do_page_mkwrite+0x14d/0x310 mm/memory.c:3361
 wp_page_shared mm/memory.c:3762 [inline]
 do_wp_page+0x268d/0x5800 mm/memory.c:3981
 handle_pte_fault mm/memory.c:6068 [inline]
 __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7efe916651c9
Code: ff ff ff 01 64 48 8b 04 25 00 00 00 00 48 8d b8 c8 fe ff ff e8 68 59 0c 00 85 c0 75 10 48 8b 44 24 68 48 8b b4 24 98 00 00 00 <48> 89 30 64 f0 83 2c 25 90 ff ff ff 01 48 8b 84 24 80 00 00 00 48
RSP: 002b:00007fff280eb9c0 EFLAGS: 00010246
RAX: 00002000000015c0 RBX: 0000000000000002 RCX: ffffffffffffff7f
RDX: c0b6bdd36fbbe298 RSI: 0000200000000080 RDI: 000055557d8cc3c8
RBP: 00007efe919d7da0 R08: 0000001b31920000 R09: 0000000000000002
R10: 0000000000000000 R11: 0000000000000001 R12: 00007efe919d609c
R13: 00007efe919d6090 R14: fffffffffffffffe R15: 00007fff280ebad0
 </TASK>