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NILFS (loop0): vblocknr = 23 has abnormal lifetime: start cno (= 4294967298) > current cno (= 3)
NILFS error (device loop0): nilfs_bmap_propagate: broken bmap (inode number=4)
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 Not tainted
------------------------------------------------------
segctord/5821 is trying to acquire lock:
ffff88814d79f090 (&nilfs->ns_sem){++++}-{4:4}, at: nilfs_set_error fs/nilfs2/super.c:92 [inline]
ffff88814d79f090 (&nilfs->ns_sem){++++}-{4:4}, at: __nilfs_error+0x1ca/0x4b0 fs/nilfs2/super.c:141

but task is already holding lock:
ffff88814d79f2a0 (&nilfs->ns_segctor_sem){++++}-{4:4}, at: nilfs_transaction_lock+0x253/0x4c0 fs/nilfs2/segment.c:357

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (&nilfs->ns_segctor_sem){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
       nilfs_transaction_begin+0x365/0x710 fs/nilfs2/segment.c:221
       nilfs_page_mkwrite+0x8b0/0xc20 fs/nilfs2/file.c:95
       do_page_mkwrite+0x14a/0x310 mm/memory.c:3287
       wp_page_shared mm/memory.c:3688 [inline]
       do_wp_page+0x2626/0x5760 mm/memory.c:3907
       handle_pte_fault mm/memory.c:6013 [inline]
       __handle_mm_fault+0x1028/0x5380 mm/memory.c:6140
       handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309
       do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1337
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #5 (sb_internal#2){.+.+}-{0:0}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       percpu_down_read include/linux/percpu-rwsem.h:52 [inline]
       __sb_start_write include/linux/fs.h:1783 [inline]
       sb_start_intwrite include/linux/fs.h:1966 [inline]
       nilfs_transaction_begin+0x268/0x710 fs/nilfs2/segment.c:218
       nilfs_page_mkwrite+0x8b0/0xc20 fs/nilfs2/file.c:95
       do_page_mkwrite+0x14a/0x310 mm/memory.c:3287
       wp_page_shared mm/memory.c:3688 [inline]
       do_wp_page+0x2626/0x5760 mm/memory.c:3907
       handle_pte_fault mm/memory.c:6013 [inline]
       __handle_mm_fault+0x1028/0x5380 mm/memory.c:6140
       handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309
       do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1337
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #4 (sb_pagefaults){.+.+}-{0:0}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       percpu_down_read include/linux/percpu-rwsem.h:52 [inline]
       __sb_start_write include/linux/fs.h:1783 [inline]
       sb_start_pagefault include/linux/fs.h:1948 [inline]
       nilfs_page_mkwrite+0x21e/0xc20 fs/nilfs2/file.c:57
       do_page_mkwrite+0x14a/0x310 mm/memory.c:3287
       wp_page_shared mm/memory.c:3688 [inline]
       do_wp_page+0x2626/0x5760 mm/memory.c:3907
       handle_pte_fault mm/memory.c:6013 [inline]
       __handle_mm_fault+0x1028/0x5380 mm/memory.c:6140
       handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309
       do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1337
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #3 (vm_lock){++++}-{0:0}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       __vma_enter_locked+0x182/0x380 mm/memory.c:6473
       __vma_start_write+0x1e/0x120 mm/memory.c:6497
       vma_start_write include/linux/mm.h:829 [inline]
       mprotect_fixup+0x571/0x9b0 mm/mprotect.c:670
       setup_arg_pages+0x53a/0xaa0 fs/exec.c:780
       load_elf_binary+0xb7a/0x27b0 fs/binfmt_elf.c:1019
       search_binary_handler fs/exec.c:1778 [inline]
       exec_binprm fs/exec.c:1810 [inline]
       bprm_execve+0x999/0x1440 fs/exec.c:1862
       kernel_execve+0x8f0/0x9f0 fs/exec.c:2028
       try_to_run_init_process+0x13/0x60 init/main.c:1385
       kernel_init+0xad/0x1d0 init/main.c:1513
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       __might_fault+0xcc/0x130 mm/memory.c:7151
       _copy_to_iter+0xf3/0x15a0 lib/iov_iter.c:184
       copy_page_to_iter+0xa7/0x150 lib/iov_iter.c:362
       copy_folio_to_iter include/linux/uio.h:198 [inline]
       filemap_read+0x78d/0x11d0 mm/filemap.c:2753
       blkdev_read_iter+0x30a/0x440 block/fops.c:809
       new_sync_read fs/read_write.c:489 [inline]
       vfs_read+0x4cd/0x980 fs/read_write.c:570
       ksys_read+0x145/0x250 fs/read_write.c:713
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&sb->s_type->i_mutex_key#7){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
       inode_lock include/linux/fs.h:867 [inline]
       set_blocksize+0x23b/0x500 block/bdev.c:203
       sb_set_blocksize block/bdev.c:224 [inline]
       sb_min_blocksize+0x119/0x210 block/bdev.c:239
       init_nilfs+0x43/0x690 fs/nilfs2/the_nilfs.c:710
       nilfs_fill_super+0x8f/0x650 fs/nilfs2/super.c:1060
       nilfs_get_tree+0x4f4/0x870 fs/nilfs2/super.c:1228
       vfs_get_tree+0x8f/0x2b0 fs/super.c:1759
       do_new_mount+0x24a/0xa40 fs/namespace.c:3884
       do_mount fs/namespace.c:4224 [inline]
       __do_sys_mount fs/namespace.c:4435 [inline]
       __se_sys_mount+0x317/0x410 fs/namespace.c:4412
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&nilfs->ns_sem){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
       __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
       nilfs_set_error fs/nilfs2/super.c:92 [inline]
       __nilfs_error+0x1ca/0x4b0 fs/nilfs2/super.c:141
       nilfs_bmap_convert_error fs/nilfs2/bmap.c:35 [inline]
       nilfs_bmap_propagate+0x108/0x130 fs/nilfs2/bmap.c:332
       nilfs_collect_file_data+0x4f/0xd0 fs/nilfs2/segment.c:589
       nilfs_segctor_apply_buffers+0x161/0x330 fs/nilfs2/segment.c:1010
       nilfs_segctor_scan_file+0x68e/0x8e0 fs/nilfs2/segment.c:1059
       nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1254 [inline]
       nilfs_segctor_collect fs/nilfs2/segment.c:1547 [inline]
       nilfs_segctor_do_construct+0x1d46/0x6970 fs/nilfs2/segment.c:2122
       nilfs_segctor_construct+0x17b/0x690 fs/nilfs2/segment.c:2478
       nilfs_segctor_thread_construct fs/nilfs2/segment.c:2586 [inline]
       nilfs_segctor_thread+0x6f7/0xe00 fs/nilfs2/segment.c:2700
       kthread+0x70e/0x8a0 kernel/kthread.c:464
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
  &nilfs->ns_sem --> sb_internal#2 --> &nilfs->ns_segctor_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&nilfs->ns_segctor_sem);
                               lock(sb_internal#2);
                               lock(&nilfs->ns_segctor_sem);
  lock(&nilfs->ns_sem);

 *** DEADLOCK ***

1 lock held by segctord/5821:
 #0: ffff88814d79f2a0 (&nilfs->ns_segctor_sem){++++}-{4:4}, at: nilfs_transaction_lock+0x253/0x4c0 fs/nilfs2/segment.c:357

stack backtrace:
CPU: 0 UID: 0 PID: 5821 Comm: segctord Not tainted 6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2079
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211
 check_prev_add kernel/locking/lockdep.c:3166 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
 nilfs_set_error fs/nilfs2/super.c:92 [inline]
 __nilfs_error+0x1ca/0x4b0 fs/nilfs2/super.c:141
 nilfs_bmap_convert_error fs/nilfs2/bmap.c:35 [inline]
 nilfs_bmap_propagate+0x108/0x130 fs/nilfs2/bmap.c:332
 nilfs_collect_file_data+0x4f/0xd0 fs/nilfs2/segment.c:589
 nilfs_segctor_apply_buffers+0x161/0x330 fs/nilfs2/segment.c:1010
 nilfs_segctor_scan_file+0x68e/0x8e0 fs/nilfs2/segment.c:1059
 nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1254 [inline]
 nilfs_segctor_collect fs/nilfs2/segment.c:1547 [inline]
 nilfs_segctor_do_construct+0x1d46/0x6970 fs/nilfs2/segment.c:2122
 nilfs_segctor_construct+0x17b/0x690 fs/nilfs2/segment.c:2478
 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2586 [inline]
 nilfs_segctor_thread+0x6f7/0xe00 fs/nilfs2/segment.c:2700
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Remounting filesystem read-only