WARNING in futex_hash_allocate

Status: upstream: reported C repro on 2026/08/09 19:12
Subsystems: kernel
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+350a93852ac854927f45@syzkaller.appspotmail.com
First crash: 1d09h, last: 1h13m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
483a9628 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in futex_hash_allocate 2026/08/10 00:22 2026/08/10 00:22 2026/08/10 01:05 5d63f80b
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] WARNING in futex_hash_allocate 0 (1) 2026/08/09 19:12

Sample crash report:
------------[ cut here ]------------
do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff81e25edd>] prepare_to_wait_event+0x8d/0x720 kernel/sched/wait.c:317
WARNING: kernel/sched/core.c:9120 at __might_sleep+0x94/0xc0 kernel/sched/core.c:9120, CPU#0: syz.0.17/5928
Modules linked in:
CPU: 0 UID: 0 PID: 5928 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__might_sleep+0x97/0xc0 kernel/sched/core.c:9120
Code: 8b 94 24 70 18 00 00 48 85 d2 75 14 48 83 c4 08 89 ee 48 89 df 31 d2 5b 5d 41 5c e9 33 fc ff ff 48 8d 3d 2c 23 4f 0f 48 89 d1 <67> 48 0f b9 3a eb db e8 5d 3d a5 00 eb 9f 89 74 24 04 e8 82 3d a5
RSP: 0018:ffffc900037efb88 EFLAGS: 00010286
RAX: dffffc0000000000 RBX: ffffffff8bcfd700 RCX: ffffffff81e25edd
RDX: ffffffff81e25edd RSI: 0000000000000002 RDI: ffffffff9124e750
RBP: 000000000000026f R08: ffffffff81fc6852 R09: 0000000000000000
R10: ffffc900037efd38 R11: 0000000000000000 R12: ffff88802b582540
R13: 0000000000000000 R14: dffffc0000000000 R15: ffffffff8e80ae80
FS:  00007efd31a166c0(0000) GS:ffff8880d5dec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efd31a15ff8 CR3: 000000001c3ea000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __mutex_lock_common kernel/locking/mutex.c:623 [inline]
 __mutex_lock+0x10e/0x1bd0 kernel/locking/mutex.c:821
 class_mutex_constructor include/linux/mutex.h:253 [inline]
 futex_pivot_pending kernel/futex/core.c:1789 [inline]
 futex_hash_allocate+0xd22/0x1120 kernel/futex/core.c:1872
 futex_hash_prctl+0x1b8/0x390 kernel/futex/core.c:2027
 __do_sys_prctl+0x16dd/0x2270 kernel/sys.c:2885
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efd30b9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007efd31a16028 EFLAGS: 00000246 ORIG_RAX: 000000000000009d
RAX: ffffffffffffffda RBX: 00007efd30e25fa0 RCX: 00007efd30b9e0d9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 000000000000004e
RBP: 00007efd30c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efd30e26038 R14: 00007efd30e25fa0 R15: 00007ffc8e6af968
 </TASK>
----------------
Code disassembly (best guess):
   0:	8b 94 24 70 18 00 00 	mov    0x1870(%rsp),%edx
   7:	48 85 d2             	test   %rdx,%rdx
   a:	75 14                	jne    0x20
   c:	48 83 c4 08          	add    $0x8,%rsp
  10:	89 ee                	mov    %ebp,%esi
  12:	48 89 df             	mov    %rbx,%rdi
  15:	31 d2                	xor    %edx,%edx
  17:	5b                   	pop    %rbx
  18:	5d                   	pop    %rbp
  19:	41 5c                	pop    %r12
  1b:	e9 33 fc ff ff       	jmp    0xfffffc53
  20:	48 8d 3d 2c 23 4f 0f 	lea    0xf4f232c(%rip),%rdi        # 0xf4f2353
  27:	48 89 d1             	mov    %rdx,%rcx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb db                	jmp    0xc
  31:	e8 5d 3d a5 00       	call   0xa53d93
  36:	eb 9f                	jmp    0xffffffd7
  38:	89 74 24 04          	mov    %esi,0x4(%rsp)
  3c:	e8                   	.byte 0xe8
  3d:	82                   	(bad)
  3e:	3d                   	.byte 0x3d
  3f:	a5                   	movsl  %ds:(%rsi),%es:(%rdi)

Crashes (856):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/09 03:26 upstream 06cf61899d64 5d63f80b .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/10 09:00 upstream db2ddb871435 558388e4 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/10 07:31 upstream b9b3e33b70b7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in futex_hash_allocate
2026/08/10 04:05 upstream b643e495ae92 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/10 03:03 upstream b643e495ae92 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/10 01:57 upstream b643e495ae92 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in futex_hash_allocate
2026/08/09 22:38 upstream b643e495ae92 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in futex_hash_allocate
2026/08/09 21:45 upstream b9b3e33b70b7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/09 17:32 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in futex_hash_allocate
2026/08/09 16:14 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/09 13:28 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/09 12:12 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in futex_hash_allocate
2026/08/09 08:20 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in futex_hash_allocate
2026/08/09 07:46 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/09 07:12 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/09 07:00 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/09 06:46 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/09 06:23 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/09 05:39 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in futex_hash_allocate
2026/08/09 05:32 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in futex_hash_allocate
2026/08/09 05:26 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/09 05:23 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in futex_hash_allocate
2026/08/09 05:10 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in futex_hash_allocate
2026/08/09 05:01 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in futex_hash_allocate
2026/08/09 04:48 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in futex_hash_allocate
2026/08/09 04:40 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/09 04:11 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/09 03:56 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in futex_hash_allocate
2026/08/09 03:46 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in futex_hash_allocate
2026/08/09 03:34 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in futex_hash_allocate
2026/08/09 23:56 upstream b9b3e33b70b7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
2026/08/09 09:05 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
2026/08/09 08:36 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
2026/08/09 07:33 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
2026/08/09 06:37 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
2026/08/09 06:07 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
2026/08/09 22:02 upstream b643e495ae92 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/09 19:54 upstream b643e495ae92 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/09 18:14 upstream b643e495ae92 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/09 15:24 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/09 10:07 upstream 06cf61899d64 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/09 08:52 upstream 06cf61899d64 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/09 03:09 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/09 20:02 upstream b643e495ae92 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 19:23 upstream b643e495ae92 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 15:37 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 05:46 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 05:42 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 05:18 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 04:25 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 03:22 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/09 03:03 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/10 10:20 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux master db2ddb871435 558388e4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64-compat WARNING in futex_hash_allocate
2026/08/10 05:36 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux master db2ddb871435 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64 WARNING in futex_hash_allocate
* Struck through repros no longer work on HEAD.