[v6.6] possible deadlock in hfsplus_block_allocate

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0a805b6ea8cd Linux 6.6.116
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1790b812580000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=8ebd19ca442a1085bae2
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/13874446b4b2/disk-0a805b6e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/69a5e59e1ade/vmlinux-0a805b6e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/322c0711f976/bzImage-0a805b6e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8ebd19...@syzkaller.appspotmail.com

loop2: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1425/10055 is trying to acquire lock:
ffff8880773e88f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff888025f18e88 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1fd/0x1990 fs/hfsplus/extents.c:455

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+0x129/0xcc0 kernel/locking/mutex.c:747
hfsplus_get_block+0x39f/0x1530 fs/hfsplus/extents.c:260
block_read_full_folio+0x42e/0xf40 fs/buffer.c:2406
filemap_read_folio+0x167/0x760 mm/filemap.c:2420
do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3789
do_read_cache_page+0x32/0x250 mm/filemap.c:3855
read_mapping_page include/linux/pagemap.h:892 [inline]
hfsplus_block_allocate+0xff/0x8e0 fs/hfsplus/bitmap.c:37
hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
hfsplus_get_block+0x412/0x1530 fs/hfsplus/extents.c:245
__block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
__block_write_begin fs/buffer.c:2173 [inline]
block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
cont_write_begin+0x5c8/0x7e0 fs/buffer.c:2591
hfsplus_write_begin+0x8b/0xd0 fs/hfsplus/inode.c:52
page_symlink+0x243/0x3c0 fs/namei.c:5238
hfsplus_symlink+0xca/0x260 fs/hfsplus/dir.c:449
vfs_symlink+0x138/0x2b0 fs/namei.c:4481
do_symlinkat+0x1b2/0x3f0 fs/namei.c:4507
__do_sys_symlinkat fs/namei.c:4523 [inline]
__se_sys_symlinkat fs/namei.c:4520 [inline]
__x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4520
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 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:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35
hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
hfsplus_bmap_reserve+0x122/0x500 fs/hfsplus/btree.c:358
hfsplus_create_cat+0x184/0xff0 fs/hfsplus/catalog.c:272
hfsplus_fill_super+0x12fa/0x1b90 fs/hfsplus/super.c:573
mount_bdev+0x22b/0x2d0 fs/super.c:1643
legacy_get_tree+0xea/0x180 fs/fs_context.c:662
vfs_get_tree+0x8c/0x280 fs/super.c:1764
do_new_mount+0x24b/0xa40 fs/namespace.c:3386
do_mount fs/namespace.c:3726 [inline]
__do_sys_mount fs/namespace.c:3935 [inline]
__se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 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 ***

4 locks held by syz.2.1425/10055:
#0: ffff8880263180e0 (&type->s_umount_key#106){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
#0: ffff8880263180e0 (&type->s_umount_key#106){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
#0: ffff8880263180e0 (&type->s_umount_key#106){+.+.}-{3:3}, at: mount_bdev+0x1e8/0x2d0 fs/super.c:1641
#1: ffff8880773e8998 (&sbi->vh_mutex){+.+.}-{3:3}, at: hfsplus_fill_super+0x128a/0x1b90 fs/hfsplus/super.c:566
#2: ffff88807a7aa0b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x154/0x1d0 fs/hfsplus/bfind.c:28
#3: ffff888025f18e88 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1fd/0x1990 fs/hfsplus/extents.c:455

stack backtrace:
CPU: 0 PID: 10055 Comm: syz.2.1425 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35
hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
hfsplus_bmap_reserve+0x122/0x500 fs/hfsplus/btree.c:358
hfsplus_create_cat+0x184/0xff0 fs/hfsplus/catalog.c:272
hfsplus_fill_super+0x12fa/0x1b90 fs/hfsplus/super.c:573
mount_bdev+0x22b/0x2d0 fs/super.c:1643
legacy_get_tree+0xea/0x180 fs/fs_context.c:662
vfs_get_tree+0x8c/0x280 fs/super.c:1764
do_new_mount+0x24b/0xa40 fs/namespace.c:3386
do_mount fs/namespace.c:3726 [inline]
__do_sys_mount fs/namespace.c:3935 [inline]
__se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f41d3990e6a
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:00007f41d47f5e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f41d47f5ef0 RCX: 00007f41d3990e6a
RDX: 0000200000000100 RSI: 0000200000002900 RDI: 00007f41d47f5eb0
RBP: 0000200000000100 R08: 00007f41d47f5ef0 R09: 0000000002000010
R10: 0000000002000010 R11: 0000000000000246 R12: 0000200000002900
R13: 00007f41d47f5eb0 R14: 00000000000006e5 R15: 00002000000022c0
</TASK>
hfsplus: xattr searching failed


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