syzbot

loop2: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.195/7010 is trying to acquire lock:
ffff88801bb9a8f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff88801cebbdc8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1fd/0x1990 fs/hfsplus/extents.c:455

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       hfsplus_get_block+0x39f/0x1530 fs/hfsplus/extents.c:260
       block_read_full_folio+0x42e/0xf40 fs/buffer.c:2406
       filemap_read_folio+0x167/0x760 mm/filemap.c:2420
       do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3804
       do_read_cache_page+0x32/0x250 mm/filemap.c:3870
       read_mapping_page include/linux/pagemap.h:892 [inline]
       hfsplus_block_allocate+0xff/0x8e0 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
       hfsplus_get_block+0x412/0x1530 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
       __block_write_begin fs/buffer.c:2173 [inline]
       block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
       cont_write_begin+0x5c8/0x7e0 fs/buffer.c:2591
       hfsplus_write_begin+0x8b/0xd0 fs/hfsplus/inode.c:52
       generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
       generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152
       __kernel_write_iter+0x274/0x670 fs/read_write.c:517
       __kernel_write+0xf0/0x140 fs/read_write.c:537
       __dump_emit+0x206/0x310 fs/coredump.c:882
       elf_core_dump+0x28fe/0x36e0 fs/binfmt_elf.c:2136
       do_coredump+0x1755/0x2480 fs/coredump.c:833
       get_signal+0x1133/0x1400 kernel/signal.c:2888
       arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
       exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
       exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
       irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:315
       exc_page_fault+0x8f/0x110 arch/x86/mm/fault.c:1524
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608

-> #0 (&sbi->alloc_mutex){+.+.}-{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
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35
       hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
       hfsplus_bmap_reserve+0x122/0x500 fs/hfsplus/btree.c:358
       hfsplus_create_cat+0x184/0xff0 fs/hfsplus/catalog.c:272
       hfsplus_fill_super+0x12fa/0x1b90 fs/hfsplus/super.c:573
       mount_bdev+0x22b/0x2d0 fs/super.c:1643
       legacy_get_tree+0xea/0x180 fs/fs_context.c:662
       vfs_get_tree+0x8c/0x280 fs/super.c:1764
       do_new_mount+0x24b/0xa40 fs/namespace.c:3386
       do_mount fs/namespace.c:3726 [inline]
       __do_sys_mount fs/namespace.c:3935 [inline]
       __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
       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:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&HFSPLUS_I(inode)->extents_lock
);
                               lock(&sbi->alloc_mutex);
                               lock(&HFSPLUS_I(inode)->extents_lock);
  lock(&sbi->alloc_mutex);

 *** DEADLOCK ***

4 locks held by syz.2.195/7010:
 #0: ffff8880568880e0 (&type->s_umount_key#61){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880568880e0 (&type->s_umount_key#61){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880568880e0 (&type->s_umount_key#61){+.+.}-{3:3}, at: mount_bdev+0x1e8/0x2d0 fs/super.c:1641
 #1: ffff88801bb9a998 (&sbi->vh_mutex){+.+.}-{3:3}, at: hfsplus_fill_super+0x128a/0x1b90 fs/hfsplus/super.c:566
 #2: ffff888056dfa0b0 (&tree->tree_lock#2){+.+.}-{3:3}, at: hfsplus_find_init+0x154/0x1d0 fs/hfsplus/bfind.c:28
 #3: 
ffff88801cebbdc8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1fd/0x1990 fs/hfsplus/extents.c:455

stack backtrace:
CPU: 1 PID: 7010 Comm: syz.2.195 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35
 hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
 hfsplus_bmap_reserve+0x122/0x500 fs/hfsplus/btree.c:358
 hfsplus_create_cat+0x184/0xff0 fs/hfsplus/catalog.c:272
 hfsplus_fill_super+0x12fa/0x1b90 fs/hfsplus/super.c:573
 mount_bdev+0x22b/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
 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: 0033:0x7f4040d90eea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f4041cbae68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4041cbaef0 RCX: 00007f4040d90eea
RDX: 0000200000000100 RSI: 0000200000002900 RDI: 00007f4041cbaeb0
RBP: 0000200000000100 R08: 00007f4041cbaef0 R09: 0000000002000010
R10: 0000000002000010 R11: 0000000000000246 R12: 0000200000002900
R13: 00007f4041cbaeb0 R14: 00000000000006d0 R15: 00002000000022c0
 </TASK>
hfsplus: xattr searching failed