[v6.1] possible deadlock in hfsplus_block_free (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3db754f56897 Linux 6.1.152
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1136ec7c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=2df8b8fe48c65624e526
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/662de00db314/disk-3db754f5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74288f70f46c/vmlinux-3db754f5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab4512d1fabb/bzImage-3db754f5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2df8b8...@syzkaller.appspotmail.com

======================================================
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>


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