syzbot

loop0: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.26/6113 is trying to acquire lock:
ffff888037cc00a0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfsplus_find_init+0x168/0x290 fs/hfsplus/bfind.c:28

but task is already holding lock:
ffff888051bc0ff8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2a4/0xc70 fs/hfsplus/extents.c:573

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_file_extend+0x1f8/0x1ba0 fs/hfsplus/extents.c:453
       hfsplus_bmap_reserve+0x125/0x500 fs/hfsplus/btree.c:358
       __hfsplus_ext_write_extent+0x2b0/0x5e0 fs/hfsplus/extents.c:104
       __hfsplus_ext_cache_extent+0x9f/0xd40 fs/hfsplus/extents.c:186
       hfsplus_ext_read_extent fs/hfsplus/extents.c:218 [inline]
       hfsplus_file_extend+0x437/0x1ba0 fs/hfsplus/extents.c:457
       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

-> #0 (&tree->tree_lock/1){+.+.}-{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_find_init+0x168/0x290 fs/hfsplus/bfind.c:28
       hfsplus_file_truncate+0x388/0xc70 fs/hfsplus/extents.c:579
       hfsplus_write_begin+0xa8/0xb0 fs/hfsplus/inode.c:52
       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(&tree->tree_lock/1);
                               lock(&HFSPLUS_I(inode)->extents_lock);
  lock(&tree->tree_lock/1);

 *** DEADLOCK ***

3 locks held by syz.0.26/6113:
 #0: ffff888028b36480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:508
 #1: ffff888051bc1258 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:985 [inline]
 #1: ffff888051bc1258 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: do_truncate+0x171/0x220 fs/open.c:63
 #2: ffff888051bc0ff8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2a4/0xc70 fs/hfsplus/extents.c:573

stack backtrace:
CPU: 0 UID: 0 PID: 6113 Comm: syz.0.26 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_find_init+0x168/0x290 fs/hfsplus/bfind.c:28
 hfsplus_file_truncate+0x388/0xc70 fs/hfsplus/extents.c:579
 hfsplus_write_begin+0xa8/0xb0 fs/hfsplus/inode.c:52
 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: 0033:0x7fa84ccfefc9
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:00007ffde88f2e78 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007fa84cf55fa0 RCX: 00007fa84ccfefc9
RDX: 0000000000000000 RSI: 0000000003000000 RDI: 0000200000000900
RBP: 00007fa84cd81f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa84cf55fa0 R14: 00007fa84cf55fa0 R15: 0000000000000002
 </TASK>