syzbot

loop1: detected capacity change from 0 to 1024
hfsplus: xattr searching failed
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.580/6760 is trying to acquire lock:
ffff888076ec60f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_free+0xc1/0x4d0 fs/hfsplus/bitmap.c:182

but task is already holding lock:
ffff8880197b3708 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x2a0/0xb40 fs/hfsplus/extents.c:574

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+0x1eb/0x2390 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hfsplus_get_block+0x39b/0x1530 fs/hfsplus/extents.c:260
       block_read_full_page+0x2e8/0xd10 fs/buffer.c:2290
       do_read_cache_page+0x8a1/0x1030 mm/filemap.c:-1
       read_mapping_page include/linux/pagemap.h:515 [inline]
       hfsplus_block_allocate+0xf4/0x900 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xa8e/0x1950 fs/hfsplus/extents.c:466
       hfsplus_get_block+0x40e/0x1530 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x54e/0x15a0 fs/buffer.c:2012
       __block_write_begin fs/buffer.c:2062 [inline]
       block_write_begin fs/buffer.c:2122 [inline]
       cont_write_begin+0x58a/0x7b0 fs/buffer.c:2471
       hfsplus_write_begin+0x92/0xe0 fs/hfsplus/inode.c:53
       __page_symlink+0xf6/0x1f0 fs/namei.c:5199
       hfsplus_symlink+0xc6/0x260 fs/hfsplus/dir.c:449
       vfs_symlink+0x247/0x3d0 fs/namei.c:4437
       do_symlinkat+0x1be/0x6c0 fs/namei.c:4466
       __do_sys_symlink fs/namei.c:4488 [inline]
       __se_sys_symlink fs/namei.c:4486 [inline]
       __x64_sys_symlink+0x7a/0x90 fs/namei.c:4486
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&sbi->alloc_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hfsplus_block_free+0xc1/0x4d0 fs/hfsplus/bitmap.c:182
       hfsplus_free_extents+0x42d/0xa50 fs/hfsplus/extents.c:371
       hfsplus_file_truncate+0x745/0xb40 fs/hfsplus/extents.c:589
       hfsplus_setattr+0x1c0/0x280 fs/hfsplus/inode.c:267
       notify_change+0xbcd/0xee0 fs/attr.c:505
       do_truncate+0x197/0x220 fs/open.c:65
       vfs_truncate+0x262/0x2f0 fs/open.c:111
       do_sys_truncate+0xdc/0x190 fs/open.c:134
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.1.580/6760:
 #0: ffff888076d26460 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff8880197b3900 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff8880197b3900 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: do_truncate+0x183/0x220 fs/open.c:63
 #2: ffff8880197b3708 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x2a0/0xb40 fs/hfsplus/extents.c:574

stack backtrace:
CPU: 0 PID: 6760 Comm: syz.1.580 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 hfsplus_block_free+0xc1/0x4d0 fs/hfsplus/bitmap.c:182
 hfsplus_free_extents+0x42d/0xa50 fs/hfsplus/extents.c:371
 hfsplus_file_truncate+0x745/0xb40 fs/hfsplus/extents.c:589
 hfsplus_setattr+0x1c0/0x280 fs/hfsplus/inode.c:267
 notify_change+0xbcd/0xee0 fs/attr.c:505
 do_truncate+0x197/0x220 fs/open.c:65
 vfs_truncate+0x262/0x2f0 fs/open.c:111
 do_sys_truncate+0xdc/0x190 fs/open.c:134
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f00b6659fc9
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:00007f00b48c1038 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007f00b68b0fa0 RCX: 00007f00b6659fc9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000200000000140
RBP: 00007f00b66dcf91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f00b68b1038 R14: 00007f00b68b0fa0 R15: 00007ffce0192e68
 </TASK>