======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.159/6782 is trying to acquire lock:
ffff88805e57e0e8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0xa7/0xc40 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff88803b86f178 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1f8/0x1ba0 fs/hfsplus/extents.c:453

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547
       hfsplus_get_block+0x39a/0x15e0 fs/hfsplus/extents.c:260
       block_read_full_folio+0x29f/0x830 fs/buffer.c:2420
       filemap_read_folio+0x117/0x380 mm/filemap.c:2444
       do_read_cache_folio+0x2ba/0x560 mm/filemap.c:4037
       do_read_cache_page mm/filemap.c:4103 [inline]
       read_cache_page+0x5d/0x170 mm/filemap.c:4112
       read_mapping_page include/linux/pagemap.h:993 [inline]
       hfsplus_block_allocate+0xf3/0xc40 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xa9a/0x1ba0 fs/hfsplus/extents.c:464
       hfsplus_get_block+0x40c/0x15e0 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
       block_write_begin fs/buffer.c:2256 [inline]
       cont_write_begin+0x789/0xb50 fs/buffer.c:2594
       hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
       page_symlink+0x26f/0x430 fs/namei.c:5598
       hfsplus_symlink+0xca/0x260 fs/hfsplus/dir.c:449
       vfs_symlink+0x143/0x2f0 fs/namei.c:4817
       do_symlinkat+0x1b1/0x3f0 fs/namei.c:4843
       __do_sys_symlink fs/namei.c:4864 [inline]
       __se_sys_symlink fs/namei.c:4862 [inline]
       __x64_sys_symlink+0x7a/0x90 fs/namei.c:4862
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&sbi->alloc_mutex){+.+.}-{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
       __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547
       hfsplus_block_allocate+0xa7/0xc40 fs/hfsplus/bitmap.c:35
       hfsplus_file_extend+0xa9a/0x1ba0 fs/hfsplus/extents.c:464
       hfsplus_get_block+0x40c/0x15e0 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
       block_write_begin fs/buffer.c:2256 [inline]
       cont_write_begin+0x789/0xb50 fs/buffer.c:2594
       hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
       cont_expand_zero fs/buffer.c:2522 [inline]
       cont_write_begin+0x2fd/0xb50 fs/buffer.c:2584
       hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
       generic_cont_expand_simple+0x13f/0x210 fs/buffer.c:2485
       hfsplus_setattr+0x169/0x270 fs/hfsplus/inode.c:260
       notify_change+0xc18/0xf60 fs/attr.c:546
       do_truncate+0x1a4/0x220 fs/open.c:68
       vfs_truncate+0x493/0x520 fs/open.c:118
       do_sys_truncate+0xdb/0x190 fs/open.c:141
       __do_sys_truncate fs/open.c:153 [inline]
       __se_sys_truncate fs/open.c:151 [inline]
       __x64_sys_truncate+0x5b/0x70 fs/open.c:151
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

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 ***

3 locks held by syz.2.159/6782:
 #0: ffff888064a60480 (sb_writers#23){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
 #1: ffff88803b86f3d8 (&sb->s_type->i_mutex_key#30){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:985 [inline]
 #1: ffff88803b86f3d8 (&sb->s_type->i_mutex_key#30){+.+.}-{4:4}, at: do_truncate+0x171/0x220 fs/open.c:63
 #2: ffff88803b86f178 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1f8/0x1ba0 fs/hfsplus/extents.c:453

stack backtrace:
CPU: 1 UID: 0 PID: 6782 Comm: syz.2.159 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
 __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547
 hfsplus_block_allocate+0xa7/0xc40 fs/hfsplus/bitmap.c:35
 hfsplus_file_extend+0xa9a/0x1ba0 fs/hfsplus/extents.c:464
 hfsplus_get_block+0x40c/0x15e0 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
 block_write_begin fs/buffer.c:2256 [inline]
 cont_write_begin+0x789/0xb50 fs/buffer.c:2594
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
 cont_expand_zero fs/buffer.c:2522 [inline]
 cont_write_begin+0x2fd/0xb50 fs/buffer.c:2584
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
 generic_cont_expand_simple+0x13f/0x210 fs/buffer.c:2485
 hfsplus_setattr+0x169/0x270 fs/hfsplus/inode.c:260
 notify_change+0xc18/0xf60 fs/attr.c:546
 do_truncate+0x1a4/0x220 fs/open.c:68
 vfs_truncate+0x493/0x520 fs/open.c:118
 do_sys_truncate+0xdb/0x190 fs/open.c:141
 __do_sys_truncate fs/open.c:153 [inline]
 __se_sys_truncate fs/open.c:151 [inline]
 __x64_sys_truncate+0x5b/0x70 fs/open.c:151
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc2ee04f749
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:00007fc2ec28d038 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007fc2ee2a6090 RCX: 00007fc2ee04f749
RDX: 0000000000000000 RSI: 0000000000001bfc RDI: 00002000000003c0
RBP: 00007fc2ee0d3f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc2ee2a6128 R14: 00007fc2ee2a6090 R15: 00007ffc07285f68
 </TASK>