syzbot

loop0: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.23/6109 is trying to acquire lock:
ffff888023dcd0e8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0xa7/0xc40 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff888039904478 (&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:4024
       do_read_cache_page mm/filemap.c:4090 [inline]
       read_cache_page+0x5d/0x170 mm/filemap.c:4099
       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
       generic_perform_write+0x29d/0x8c0 mm/filemap.c:4242
       generic_file_write_iter+0x118/0x550 mm/filemap.c:4385
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x5d5/0xb40 fs/read_write.c:686
       ksys_write+0x14b/0x260 fs/read_write.c:738
       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_bmap_reserve+0x125/0x500 fs/hfsplus/btree.c:358
       hfsplus_create_cat+0x18e/0x1130 fs/hfsplus/catalog.c:272
       hfsplus_fill_super+0x1313/0x1b70 fs/hfsplus/super.c:580
       get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691
       vfs_get_tree+0x92/0x2b0 fs/super.c:1751
       fc_mount fs/namespace.c:1208 [inline]
       do_new_mount_fc fs/namespace.c:3651 [inline]
       do_new_mount+0x302/0xa10 fs/namespace.c:3727
       do_mount fs/namespace.c:4050 [inline]
       __do_sys_mount fs/namespace.c:4238 [inline]
       __se_sys_mount+0x313/0x410 fs/namespace.c:4215
       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 ***

4 locks held by syz.0.23/6109:
 #0: ffff88803722a0d0 (&type->s_umount_key#53/1){+.+.}-{4:4}, at: alloc_super+0x1ba/0x9a0 fs/super.c:344
 #1: ffff888023dcd178 (&sbi->vh_mutex){+.+.}-{4:4}, at: hfsplus_fill_super+0x1296/0x1b70 fs/hfsplus/super.c:573
 #2: ffff888023c6a0a0 (&tree->tree_lock){+.+.}-{4:4}, at: hfsplus_find_init+0x168/0x290 fs/hfsplus/bfind.c:28
 #3: ffff888039904478 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1f8/0x1ba0 fs/hfsplus/extents.c:453

stack backtrace:
CPU: 0 UID: 0 PID: 6109 Comm: syz.0.23 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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_bmap_reserve+0x125/0x500 fs/hfsplus/btree.c:358
 hfsplus_create_cat+0x18e/0x1130 fs/hfsplus/catalog.c:272
 hfsplus_fill_super+0x1313/0x1b70 fs/hfsplus/super.c:580
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691
 vfs_get_tree+0x92/0x2b0 fs/super.c:1751
 fc_mount fs/namespace.c:1208 [inline]
 do_new_mount_fc fs/namespace.c:3651 [inline]
 do_new_mount+0x302/0xa10 fs/namespace.c:3727
 do_mount fs/namespace.c:4050 [inline]
 __do_sys_mount fs/namespace.c:4238 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4215
 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: 0033:0x7f675e2b066a
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:00007ffe52d2bd68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe52d2bdf0 RCX: 00007f675e2b066a
RDX: 0000200000000000 RSI: 0000200000000100 RDI: 00007ffe52d2bdb0
RBP: 0000200000000000 R08: 00007ffe52d2bdf0 R09: 000000000180000c
R10: 000000000180000c R11: 0000000000000246 R12: 0000200000000100
R13: 00007ffe52d2bdb0 R14: 00000000000006eb R15: 00002000000005c0
 </TASK>