syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.317/5644 is trying to acquire lock:
ffff888073ac48f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_free+0xbf/0x4b0 fs/hfsplus/bitmap.c:182

but task is already holding lock:
ffff8880203ca988 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x28f/0xb30 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 kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       hfsplus_get_block+0x39b/0x1530 fs/hfsplus/extents.c:260
       block_read_full_folio+0x3c9/0xed0 fs/buffer.c:2271
       filemap_read_folio+0x160/0x760 mm/filemap.c:2490
       do_read_cache_folio+0x2a0/0x760 mm/filemap.c:3627
       do_read_cache_page+0x32/0x220 mm/filemap.c:3669
       read_mapping_page include/linux/pagemap.h:791 [inline]
       hfsplus_block_allocate+0xfb/0x8e0 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+0x54b/0x1a70 fs/buffer.c:1991
       __block_write_begin fs/buffer.c:2041 [inline]
       block_write_begin+0x96/0x1e0 fs/buffer.c:2102
       cont_write_begin+0x5c4/0x7d0 fs/buffer.c:2456
       hfsplus_write_begin+0x87/0xd0 fs/hfsplus/inode.c:52
       generic_perform_write+0x2db/0x560 mm/filemap.c:3846
       __generic_file_write_iter+0x172/0x430 mm/filemap.c:3974
       generic_file_write_iter+0xab/0x2e0 mm/filemap.c:4006
       call_write_iter include/linux/fs.h:2265 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x44c/0x960 fs/read_write.c:584
       ksys_write+0x143/0x240 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&sbi->alloc_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       hfsplus_block_free+0xbf/0x4b0 fs/hfsplus/bitmap.c:182
       hfsplus_free_extents+0x10d/0xa50 fs/hfsplus/extents.c:360
       hfsplus_file_truncate+0x731/0xb30 fs/hfsplus/extents.c:589
       hfsplus_setattr+0x1c0/0x280 fs/hfsplus/inode.c:269
       notify_change+0xc74/0xf40 fs/attr.c:499
       do_truncate+0x197/0x220 fs/open.c:65
       handle_truncate fs/namei.c:3285 [inline]
       do_open fs/namei.c:3630 [inline]
       path_openat+0x27f2/0x2e70 fs/namei.c:3783
       do_filp_open+0x1c1/0x3c0 fs/namei.c:3810
       do_sys_openat2+0x142/0x490 fs/open.c:1318
       do_sys_open fs/open.c:1334 [inline]
       __do_sys_open fs/open.c:1342 [inline]
       __se_sys_open fs/open.c:1338 [inline]
       __x64_sys_open+0x11b/0x140 fs/open.c:1338
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 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 ***

3 locks held by syz.4.317/5644:
 #0: ffff8880786a8460 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:393
 #1: ffff8880203cab80 (&sb->s_type->i_mutex_key#25){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff8880203cab80 (&sb->s_type->i_mutex_key#25){+.+.}-{3:3}, at: do_truncate+0x183/0x220 fs/open.c:63
 #2: ffff8880203ca988 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x28f/0xb30 fs/hfsplus/extents.c:574

stack backtrace:
CPU: 1 PID: 5644 Comm: syz.4.317 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
 hfsplus_block_free+0xbf/0x4b0 fs/hfsplus/bitmap.c:182
 hfsplus_free_extents+0x10d/0xa50 fs/hfsplus/extents.c:360
 hfsplus_file_truncate+0x731/0xb30 fs/hfsplus/extents.c:589
 hfsplus_setattr+0x1c0/0x280 fs/hfsplus/inode.c:269
 notify_change+0xc74/0xf40 fs/attr.c:499
 do_truncate+0x197/0x220 fs/open.c:65
 handle_truncate fs/namei.c:3285 [inline]
 do_open fs/namei.c:3630 [inline]
 path_openat+0x27f2/0x2e70 fs/namei.c:3783
 do_filp_open+0x1c1/0x3c0 fs/namei.c:3810
 do_sys_openat2+0x142/0x490 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_open fs/open.c:1342 [inline]
 __se_sys_open fs/open.c:1338 [inline]
 __x64_sys_open+0x11b/0x140 fs/open.c:1338
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f629698eba9
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:00007f62977ff038 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f6296bd6090 RCX: 00007f629698eba9
RDX: 0000000000000020 RSI: 000000000014927e RDI: 00002000000001c0
RBP: 00007f6296a11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6296bd6128 R14: 00007f6296bd6090 R15: 00007ffe55ad2a88
 </TASK>