possible deadlock in hfsplus_block_allocate (3)

Status: upstream: reported C repro on 2025/01/14 13:47
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+8615b1f196bc0cecc8bb@syzkaller.appspotmail.com
First crash: 571d, last: 65d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/01/15 upstream (ToT) 7f5b6a8ec18e C [report] possible deadlock in hfsplus_block_allocate
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in hfsplus_block_allocate 4 26 831d 1227d 0/3 auto-obsoleted due to no activity on 2024/08/08 03:24
linux-4.14 possible deadlock in hfsplus_block_allocate hfsplus 4 2 1298d 1315d 0/1 upstream: reported on 2023/01/02 02:59
linux-6.1 possible deadlock in hfsplus_block_allocate (2) origin:upstream 4 syz, C error 17 98d 609d 0/3 upstream: reported C repro on 2024/12/07 22:33
upstream possible deadlock in hfsplus_block_allocate hfs 4 syz, C done error 434 6d15h 1348d 0/29 upstream: reported C repro on 2022/11/29 13:38
linux-5.15 possible deadlock in hfsplus_block_allocate (2) 4 1 735d 735d 0/3 auto-obsoleted due to no activity on 2024/11/11 18:00
linux-6.6 possible deadlock in hfsplus_block_allocate 4 2 215d 274d 0/2 auto-obsoleted due to no activity on 2026/04/15 15:45
linux-4.19 possible deadlock in hfsplus_block_allocate hfsplus 4 2 1318d 1325d 0/1 upstream: reported on 2022/12/22 13:15
linux-5.15 possible deadlock in hfsplus_block_allocate 4 18 872d 1233d 0/3 auto-obsoleted due to no activity on 2024/06/27 07:36
▶ ▼ Last patch testing requests (7)
Created Duration User Patch Repo Result
2026/06/04 11:29 25m retest repro linux-5.15.y report log
2026/03/03 15:39 11m retest repro linux-5.15.y report log
2025/12/23 13:42 10m retest repro linux-5.15.y report log
2025/09/30 15:19 1h27m retest repro linux-5.15.y report log
2025/07/21 21:06 11m retest repro linux-5.15.y report log
2025/05/11 04:15 12m retest repro linux-5.15.y report log
2025/01/28 15:09 14m retest repro linux-5.15.y report log

Sample crash report:
loop0: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
5.15.176-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor148/4108 is trying to acquire lock:
ffff0000d94bd0f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_allocate+0x8c/0x800 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff0000d67773c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x198/0x14e0 fs/hfsplus/extents.c:458

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+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       hfsplus_get_block+0x2c4/0x1194 fs/hfsplus/extents.c:260
       block_read_full_page+0x2a0/0xc4c fs/buffer.c:2290
       hfsplus_readpage+0x28/0x38 fs/hfsplus/inode.c:28
       do_read_cache_page+0x60c/0x950
       read_cache_page+0x68/0x84 mm/filemap.c:3574
       read_mapping_page include/linux/pagemap.h:515 [inline]
       hfsplus_block_allocate+0xe0/0x800 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0x770/0x14e0 fs/hfsplus/extents.c:469
       hfsplus_get_block+0x398/0x1194 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x3ec/0x1608 fs/buffer.c:2012
       __block_write_begin fs/buffer.c:2062 [inline]
       block_write_begin fs/buffer.c:2122 [inline]
       cont_write_begin+0x538/0x710 fs/buffer.c:2471
       hfsplus_write_begin+0xa8/0xf8 fs/hfsplus/inode.c:53
       pagecache_write_begin+0xa0/0xc0 mm/filemap.c:3608
       cont_expand_zero fs/buffer.c:2431 [inline]
       cont_write_begin+0x5a8/0x710 fs/buffer.c:2461
       hfsplus_write_begin+0xa8/0xf8 fs/hfsplus/inode.c:53
       pagecache_write_begin+0xa0/0xc0 mm/filemap.c:3608
       generic_cont_expand_simple+0x12c/0x208 fs/buffer.c:2362
       hfsplus_setattr+0x148/0x25c fs/hfsplus/inode.c:261
       notify_change+0xa34/0xcf8 fs/attr.c:505
       do_truncate+0x1c0/0x28c fs/open.c:65
       do_sys_ftruncate+0x288/0x31c fs/open.c:193
       __do_sys_ftruncate fs/open.c:204 [inline]
       __se_sys_ftruncate fs/open.c:202 [inline]
       __arm64_sys_ftruncate+0x60/0x74 fs/open.c:202
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&sbi->alloc_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
       lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       hfsplus_block_allocate+0x8c/0x800 fs/hfsplus/bitmap.c:35
       hfsplus_file_extend+0x770/0x14e0 fs/hfsplus/extents.c:469
       hfsplus_get_block+0x398/0x1194 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x3ec/0x1608 fs/buffer.c:2012
       __block_write_begin fs/buffer.c:2062 [inline]
       block_write_begin fs/buffer.c:2122 [inline]
       cont_write_begin+0x538/0x710 fs/buffer.c:2471
       hfsplus_write_begin+0xa8/0xf8 fs/hfsplus/inode.c:53
       pagecache_write_begin+0xa0/0xc0 mm/filemap.c:3608
       cont_expand_zero fs/buffer.c:2398 [inline]
       cont_write_begin+0x26c/0x710 fs/buffer.c:2461
       hfsplus_write_begin+0xa8/0xf8 fs/hfsplus/inode.c:53
       generic_perform_write+0x24c/0x520 mm/filemap.c:3785
       __generic_file_write_iter+0x230/0x454 mm/filemap.c:3912
       generic_file_write_iter+0xb4/0x1b8 mm/filemap.c:3944
       do_iter_readv_writev+0x420/0x5f8
       do_iter_write+0x1b8/0x66c fs/read_write.c:855
       vfs_writev fs/read_write.c:928 [inline]
       do_pwritev+0x1ec/0x334 fs/read_write.c:1025
       __do_sys_pwritev2 fs/read_write.c:1084 [inline]
       __se_sys_pwritev2 fs/read_write.c:1075 [inline]
       __arm64_sys_pwritev2+0xd4/0x108 fs/read_write.c:1075
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

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-executor148/4108:
 #0: ffff0000c93d4460 (sb_writers#8){.+.+}-{0:0}, at: vfs_writev fs/read_write.c:927 [inline]
 #0: ffff0000c93d4460 (sb_writers#8){.+.+}-{0:0}, at: do_pwritev+0x1d8/0x334 fs/read_write.c:1025
 #1: ffff0000d67775c0 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #1: ffff0000d67775c0 (&sb->s_type->i_mutex_key#17){+.+.}-{3:3}, at: generic_file_write_iter+0x84/0x1b8 mm/filemap.c:3941
 #2: ffff0000d67773c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x198/0x14e0 fs/hfsplus/extents.c:458

stack backtrace:
CPU: 1 PID: 4108 Comm: syz-executor148 Not tainted 5.15.176-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
 hfsplus_block_allocate+0x8c/0x800 fs/hfsplus/bitmap.c:35
 hfsplus_file_extend+0x770/0x14e0 fs/hfsplus/extents.c:469
 hfsplus_get_block+0x398/0x1194 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x3ec/0x1608 fs/buffer.c:2012
 __block_write_begin fs/buffer.c:2062 [inline]
 block_write_begin fs/buffer.c:2122 [inline]
 cont_write_begin+0x538/0x710 fs/buffer.c:2471
 hfsplus_write_begin+0xa8/0xf8 fs/hfsplus/inode.c:53
 pagecache_write_begin+0xa0/0xc0 mm/filemap.c:3608
 cont_expand_zero fs/buffer.c:2398 [inline]
 cont_write_begin+0x26c/0x710 fs/buffer.c:2461
 hfsplus_write_begin+0xa8/0xf8 fs/hfsplus/inode.c:53
 generic_perform_write+0x24c/0x520 mm/filemap.c:3785
 __generic_file_write_iter+0x230/0x454 mm/filemap.c:3912
 generic_file_write_iter+0xb4/0x1b8 mm/filemap.c:3944
 do_iter_readv_writev+0x420/0x5f8
 do_iter_write+0x1b8/0x66c fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x1ec/0x334 fs/read_write.c:1025
 __do_sys_pwritev2 fs/read_write.c:1084 [inline]
 __se_sys_pwritev2 fs/read_write.c:1075 [inline]
 __arm64_sys_pwritev2+0xd4/0x108 fs/read_write.c:1075
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Crashes (21):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/14 13:46 linux-5.15.y 4735586da88e b1f1cd88 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-linux-5-15-kasan-arm64 possible deadlock in hfsplus_block_allocate
2026/05/04 13:21 linux-5.15.y ef251c45f1cd 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 13:21 linux-5.15.y ef251c45f1cd 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 08:37 linux-5.15.y ef251c45f1cd 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 08:37 linux-5.15.y ef251c45f1cd 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 03:00 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:57 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:52 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:43 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:43 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:40 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:35 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:31 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:31 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/05/04 02:29 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2026/04/12 09:01 linux-5.15.y 91d48252ad4b 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2025/12/30 10:49 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2025/12/27 00:06 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2025/12/08 23:04 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in hfsplus_block_allocate
2025/06/15 22:04 linux-5.15.y 1c700860e8bc 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in hfsplus_block_allocate
2025/04/26 00:42 linux-5.15.y f7347f400572 c6b4fb39 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in hfsplus_block_allocate
* Struck through repros no longer work on HEAD.