syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.27/6089 is trying to acquire lock:
ffff888033d3d0f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0xd2/0xd10 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff88807bf93dc8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1ca/0x1320 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}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776
       hfsplus_get_block+0x272/0xac0 fs/hfsplus/extents.c:260
       block_read_full_folio+0x457/0x850 fs/buffer.c:2420
       filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2496
       do_read_cache_folio+0x266/0x5c0 mm/filemap.c:4096
       do_read_cache_page mm/filemap.c:4162 [inline]
       read_cache_page+0x5b/0x160 mm/filemap.c:4171
       read_mapping_page include/linux/pagemap.h:1011 [inline]
       hfsplus_block_allocate+0x131/0xd10 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0x459/0x1320 fs/hfsplus/extents.c:464
       hfsplus_get_block+0x1a9/0xac0 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x4f4/0x16d0 fs/buffer.c:2145
       block_write_begin+0x9d/0x1d0 fs/buffer.c:2256
       cont_write_begin+0x61a/0x950 fs/buffer.c:2594
       hfsplus_write_begin+0x64/0x120 fs/hfsplus/inode.c:48
       cont_expand_zero fs/buffer.c:2555 [inline]
       cont_write_begin+0x6ff/0x950 fs/buffer.c:2584
       hfsplus_write_begin+0x64/0x120 fs/hfsplus/inode.c:48
       generic_cont_expand_simple+0x122/0x200 fs/buffer.c:2485
       hfsplus_setattr+0x250/0x320 fs/hfsplus/inode.c:280
       notify_change+0x6d2/0x1290 fs/attr.c:546
       do_truncate+0x1d7/0x230 fs/open.c:68
       do_ftruncate+0x59e/0x920 fs/open.c:195
       do_sys_ftruncate+0x61/0xb0 fs/open.c:207
       __do_sys_ftruncate fs/open.c:212 [inline]
       __se_sys_ftruncate fs/open.c:210 [inline]
       __x64_sys_ftruncate+0x58/0x80 fs/open.c:210
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xf80 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 kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x1669/0x2890 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776
       hfsplus_block_allocate+0xd2/0xd10 fs/hfsplus/bitmap.c:35
       hfsplus_file_extend+0x459/0x1320 fs/hfsplus/extents.c:464
       hfsplus_get_block+0x1a9/0xac0 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x4f4/0x16d0 fs/buffer.c:2145
       block_write_begin+0x9d/0x1d0 fs/buffer.c:2256
       cont_write_begin+0x61a/0x950 fs/buffer.c:2594
       hfsplus_write_begin+0x64/0x120 fs/hfsplus/inode.c:48
       cont_expand_zero fs/buffer.c:2522 [inline]
       cont_write_begin+0x34f/0x950 fs/buffer.c:2584
       hfsplus_write_begin+0x64/0x120 fs/hfsplus/inode.c:48
       generic_perform_write+0x3c4/0x900 mm/filemap.c:4314
       __generic_file_write_iter+0x1f7/0x240 mm/filemap.c:4431
       generic_file_write_iter+0xe1/0x3d0 mm/filemap.c:4457
       do_iter_readv_writev+0x662/0x9e0 fs/read_write.c:827
       vfs_writev+0x35f/0xde0 fs/read_write.c:1057
       do_pwritev+0x1a6/0x270 fs/read_write.c:1153
       __do_sys_pwritev2 fs/read_write.c:1211 [inline]
       __se_sys_pwritev2 fs/read_write.c:1202 [inline]
       __x64_sys_pwritev2+0xef/0x160 fs/read_write.c:1202
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xf80 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.0.27/6089:
 #0: ffff88807bdde420 (sb_writers#12){.+.+}-{0:0}, at: do_pwritev+0x1a6/0x270 fs/read_write.c:1153
 #1: ffff88807bf93fb8 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
 #1: ffff88807bf93fb8 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: generic_file_write_iter+0x8c/0x3d0 mm/filemap.c:4454
 #2: ffff88807bf93dc8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1ca/0x1320 fs/hfsplus/extents.c:453

stack backtrace:
CPU: 1 UID: 0 PID: 6089 Comm: syz.0.27 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x340 kernel/locking/lockdep.c:2043
 check_noncircular+0x146/0x160 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 kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x1669/0x2890 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776
 hfsplus_block_allocate+0xd2/0xd10 fs/hfsplus/bitmap.c:35
 hfsplus_file_extend+0x459/0x1320 fs/hfsplus/extents.c:464
 hfsplus_get_block+0x1a9/0xac0 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x4f4/0x16d0 fs/buffer.c:2145
 block_write_begin+0x9d/0x1d0 fs/buffer.c:2256
 cont_write_begin+0x61a/0x950 fs/buffer.c:2594
 hfsplus_write_begin+0x64/0x120 fs/hfsplus/inode.c:48
 cont_expand_zero fs/buffer.c:2522 [inline]
 cont_write_begin+0x34f/0x950 fs/buffer.c:2584
 hfsplus_write_begin+0x64/0x120 fs/hfsplus/inode.c:48
 generic_perform_write+0x3c4/0x900 mm/filemap.c:4314
 __generic_file_write_iter+0x1f7/0x240 mm/filemap.c:4431
 generic_file_write_iter+0xe1/0x3d0 mm/filemap.c:4457
 do_iter_readv_writev+0x662/0x9e0 fs/read_write.c:827
 vfs_writev+0x35f/0xde0 fs/read_write.c:1057
 do_pwritev+0x1a6/0x270 fs/read_write.c:1153
 __do_sys_pwritev2 fs/read_write.c:1211 [inline]
 __se_sys_pwritev2 fs/read_write.c:1202 [inline]
 __x64_sys_pwritev2+0xef/0x160 fs/read_write.c:1202
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd41798f749
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:00007fff859fa628 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007fd417be5fa0 RCX: 00007fd41798f749
RDX: 0000000000000001 RSI: 00002000000001c0 RDI: 0000000000000005
RBP: 00007fd417a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd417be5fa0 R14: 00007fd417be5fa0 R15: 0000000000000006
 </TASK>