syzbot

======================================================
WARNING: possible circular locking dependency detected
6.1.141-syzkaller #0 Not tainted
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syz.4.420/5740 is trying to acquire lock:
ffff0000f637ea20 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_page_mkwrite+0x328/0xbf4 fs/ocfs2/mmap.c:142

but task is already holding lock:
ffff0000f7eba558 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x13c/0x358 mm/memory.c:3011

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_pagefaults#3){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1891 [inline]
       sb_start_pagefault include/linux/fs.h:1995 [inline]
       ocfs2_page_mkwrite+0x194/0xbf4 fs/ocfs2/mmap.c:122
       do_page_mkwrite+0x13c/0x358 mm/memory.c:3011
       wp_page_shared+0x148/0x550 mm/memory.c:3360
       do_wp_page+0xca0/0xef0 mm/memory.c:3510
       handle_pte_fault mm/memory.c:5049 [inline]
       __handle_mm_fault mm/memory.c:5173 [inline]
       handle_mm_fault+0x133c/0x2fd4 mm/memory.c:5294
       __do_page_fault arch/arm64/mm/fault.c:499 [inline]
       do_page_fault+0x310/0x99c arch/arm64/mm/fault.c:583
       do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:803
       el0_da+0x70/0x154 arch/arm64/kernel/entry-common.c:515
       el0t_64_sync_handler+0x90/0xf0 arch/arm64/kernel/entry-common.c:658
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc4/0x124 mm/memory.c:5852
       _copy_to_user include/linux/uaccess.h:143 [inline]
       copy_to_user include/linux/uaccess.h:169 [inline]
       fiemap_fill_next_extent+0x15c/0x3b4 fs/ioctl.c:144
       ocfs2_fiemap_inline fs/ocfs2/extent_map.c:725 [inline]
       ocfs2_fiemap+0x75c/0x9b0 fs/ocfs2/extent_map.c:762
       ioctl_fiemap fs/ioctl.c:219 [inline]
       do_vfs_ioctl+0x1694/0x206c fs/ioctl.c:810
       __do_sys_ioctl fs/ioctl.c:868 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #0 (&ocfs2_file_ip_alloc_sem_key){++++}-{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+0x293c/0x6544 kernel/locking/lockdep.c:5049
       lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
       down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
       ocfs2_page_mkwrite+0x328/0xbf4 fs/ocfs2/mmap.c:142
       do_page_mkwrite+0x13c/0x358 mm/memory.c:3011
       wp_page_shared+0x148/0x550 mm/memory.c:3360
       do_wp_page+0xca0/0xef0 mm/memory.c:3510
       handle_pte_fault mm/memory.c:5049 [inline]
       __handle_mm_fault mm/memory.c:5173 [inline]
       handle_mm_fault+0x133c/0x2fd4 mm/memory.c:5294
       __do_page_fault arch/arm64/mm/fault.c:499 [inline]
       do_page_fault+0x310/0x99c arch/arm64/mm/fault.c:583
       do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:803
       el0_da+0x70/0x154 arch/arm64/kernel/entry-common.c:515
       el0t_64_sync_handler+0x90/0xf0 arch/arm64/kernel/entry-common.c:658
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

2 locks held by syz.4.420/5740:
 #0: ffff0000ca465548 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff0000ca465548 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5322 [inline]
 #0: ffff0000ca465548 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x38/0x2e8 mm/memory.c:5384
 #1: ffff0000f7eba558 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x13c/0x358 mm/memory.c:3011

stack backtrace:
CPU: 1 PID: 5740 Comm: syz.4.420 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2048
 check_noncircular+0x240/0x2d4 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+0x293c/0x6544 kernel/locking/lockdep.c:5049
 lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
 down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
 ocfs2_page_mkwrite+0x328/0xbf4 fs/ocfs2/mmap.c:142
 do_page_mkwrite+0x13c/0x358 mm/memory.c:3011
 wp_page_shared+0x148/0x550 mm/memory.c:3360
 do_wp_page+0xca0/0xef0 mm/memory.c:3510
 handle_pte_fault mm/memory.c:5049 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x133c/0x2fd4 mm/memory.c:5294
 __do_page_fault arch/arm64/mm/fault.c:499 [inline]
 do_page_fault+0x310/0x99c arch/arm64/mm/fault.c:583
 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:803
 el0_da+0x70/0x154 arch/arm64/kernel/entry-common.c:515
 el0t_64_sync_handler+0x90/0xf0 arch/arm64/kernel/entry-common.c:658
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585