syzbot


possible deadlock in hfsplus_block_free (6)

Status: upstream: reported on 2026/05/01 12:21
Reported-by: syzbot+3518a5fb497efab248e3@syzkaller.appspotmail.com
First crash: 51d, last: 27d
Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in hfsplus_block_free (2) 4 4 744d 744d 0/3 auto-obsoleted due to no activity on 2024/09/15 13:42
linux-5.15 possible deadlock in hfsplus_block_free (4) 4 1 239d 239d 0/3 auto-obsoleted due to no activity on 2026/02/02 10:58
linux-4.14 possible deadlock in hfsplus_block_free hfsplus 4 10 1213d 1298d 0/1 upstream: reported on 2022/12/01 19:36
linux-6.1 possible deadlock in hfsplus_block_free (5) 4 1 169d 169d 0/3 auto-obsoleted due to no activity on 2026/04/13 08:07
linux-5.15 possible deadlock in hfsplus_block_free (3) 4 2 474d 475d 0/3 auto-obsoleted due to no activity on 2025/06/13 01:35
linux-4.19 possible deadlock in hfsplus_block_free hfsplus 4 20 1204d 1295d 0/1 upstream: reported on 2022/12/04 19:32
linux-6.1 possible deadlock in hfsplus_block_free (4) 4 1 276d 276d 0/3 auto-obsoleted due to no activity on 2025/12/27 09:21
upstream possible deadlock in hfsplus_block_free hfs 4 C inconclusive error 393 34d 1300d 0/29 upstream: reported C repro on 2022/11/29 08:32
linux-5.15 possible deadlock in hfsplus_block_free 4 20 972d 1175d 0/3 auto-obsoleted due to no activity on 2024/01/31 18:41
linux-5.15 possible deadlock in hfsplus_block_free (5) 4 8 21d 49d 0/3 upstream: reported on 2026/05/04 02:29
linux-6.1 possible deadlock in hfsplus_block_free (3) 4 4 428d 490d 0/3 auto-obsoleted due to no activity on 2025/07/29 00:39
linux-5.15 possible deadlock in hfsplus_block_free (2) 4 1 744d 744d 0/3 auto-obsoleted due to no activity on 2024/09/15 11:28
linux-6.1 possible deadlock in hfsplus_block_free 4 27 898d 1162d 0/3 auto-obsoleted due to no activity on 2024/04/14 19:02
linux-6.6 possible deadlock in hfsplus_block_free (2) 4 1 165d 165d 0/2 auto-obsoleted due to no activity on 2026/04/17 20:22
linux-6.6 possible deadlock in hfsplus_block_free 4 1 277d 277d 0/2 auto-obsoleted due to no activity on 2025/12/26 20:38

Sample crash report:
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/4648 is trying to acquire lock:
ffff88807cd768f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_free+0xbf/0x4b0 fs/hfsplus/bitmap.c:182

but task is already holding lock:
ffff888051c1c488 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x2b7/0xb60 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+0x12d/0xaf0 kernel/locking/mutex.c:747
       hfsplus_get_block+0x3a1/0x15a0 fs/hfsplus/extents.c:260
       block_read_full_folio+0x3e6/0xf00 fs/buffer.c:2271
       filemap_read_folio+0x16b/0x770 mm/filemap.c:2490
       do_read_cache_folio+0x2a0/0x760 mm/filemap.c:3659
       do_read_cache_page+0x32/0x220 mm/filemap.c:3701
       read_mapping_page include/linux/pagemap.h:793 [inline]
       hfsplus_block_allocate+0xdc/0x8a0 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xb1f/0x1a50 fs/hfsplus/extents.c:466
       hfsplus_get_block+0x430/0x15a0 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x55d/0x1a80 fs/buffer.c:1991
       __block_write_begin fs/buffer.c:2041 [inline]
       block_write_begin+0x96/0x1e0 fs/buffer.c:2102
       cont_write_begin+0x5ea/0x800 fs/buffer.c:2456
       hfsplus_write_begin+0x87/0xd0 fs/hfsplus/inode.c:52
       generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862
       __generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
       generic_file_write_iter+0xab/0x2e0 mm/filemap.c:3989
       __kernel_write_iter+0x285/0x650 fs/read_write.c:517
       __kernel_write+0x103/0x170 fs/read_write.c:537
       __dump_emit+0x208/0x310 fs/coredump.c:873
       elf_core_dump+0x2858/0x35d0 fs/binfmt_elf.c:2306
       do_coredump+0x165b/0x22f0 fs/coredump.c:824
       get_signal+0x10aa/0x1350 kernel/signal.c:2857
       arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871
       exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
       irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316
       exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1485
       asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608

-> #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+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12d/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+0x765/0xb60 fs/hfsplus/extents.c:589
       hfsplus_delete_inode+0x17c/0x230 fs/hfsplus/inode.c:-1
       hfsplus_unlink+0x4f7/0x7b0 fs/hfsplus/dir.c:405
       vfs_unlink+0x385/0x600 fs/namei.c:4330
       do_unlinkat+0x335/0x580 fs/namei.c:4398
       __do_sys_unlink fs/namei.c:4446 [inline]
       __se_sys_unlink fs/namei.c:4444 [inline]
       __x64_sys_unlink+0x45/0x50 fs/namei.c:4444
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       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 ***

5 locks held by syz-executor/4648:
 #0: ffff8880524f2460 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402
 #1: ffff888051c1bfc0 (&type->i_mutex_dir_key#14/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline]
 #1: ffff888051c1bfc0 (&type->i_mutex_dir_key#14/1){+.+.}-{3:3}, at: do_unlinkat+0x189/0x580 fs/namei.c:4381
 #2: ffff888051c1c680 (&sb->s_type->i_mutex_key#40){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #2: ffff888051c1c680 (&sb->s_type->i_mutex_key#40){+.+.}-{3:3}, at: vfs_unlink+0xee/0x600 fs/namei.c:4319
 #3: ffff88807cd76998 (&sbi->vh_mutex){+.+.}-{3:3}, at: hfsplus_unlink+0x175/0x7b0 fs/hfsplus/dir.c:370
 #4: ffff888051c1c488 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x2b7/0xb60 fs/hfsplus/extents.c:574

stack backtrace:
CPU: 0 PID: 4648 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 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+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12d/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+0x765/0xb60 fs/hfsplus/extents.c:589
 hfsplus_delete_inode+0x17c/0x230 fs/hfsplus/inode.c:-1
 hfsplus_unlink+0x4f7/0x7b0 fs/hfsplus/dir.c:405
 vfs_unlink+0x385/0x600 fs/namei.c:4330
 do_unlinkat+0x335/0x580 fs/namei.c:4398
 __do_sys_unlink fs/namei.c:4446 [inline]
 __se_sys_unlink fs/namei.c:4444 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4444
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9b1239bf47
Code: 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffdeef48668 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9b1239bf47
RDX: 00007ffdeef48690 RSI: 00007ffdeef48720 RDI: 00007ffdeef48720
RBP: 00007ffdeef48720 R08: 00007ffdeef49720 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffdeef49810
R13: 00007f9b124321ca R14: 00000000000bbbb0 R15: 00007ffdeef4b9d0
 </TASK>
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed
hfsplus: inconsistency in B*Tree (0,1,255,1,0)
hfsplus: xattr search failed

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/26 02:58 linux-6.1.y dcbcab9d7079 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in hfsplus_block_free
2026/05/04 10:46 linux-6.1.y 4931e0e1673d 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in hfsplus_block_free
2026/05/02 00:19 linux-6.1.y 4931e0e1673d 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in hfsplus_block_free
2026/05/01 12:21 linux-6.1.y 4931e0e1673d 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in hfsplus_block_free
* Struck through repros no longer work on HEAD.