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
Fix commit: d8aa5dd97944 futex: Fix might_sleep() warning in futex_pivot_pending()
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-arm32 ci-qemu2-riscv64 ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root]
First crash: 35d, last: 15d
Cause bisection: failed (error log, bisect log)
  
✨ AI Patch Versions (6)
Version Stage Reported Report Link Job
1 upstream 2026/08/13 06:50 Discussion 29771462-e030-4501-832d-adbf8cb167c2
5 moderation 2026/08/13 06:32 Discussion 29771462-e030-4501-832d-adbf8cb167c2
4 moderation 2026/08/13 05:36 Discussion 095e447b-214a-45ce-8877-7aa877f5d7ff
3 moderation 2026/08/13 04:08 Discussion 89be9910-7060-43cd-8969-b14a2e87a76a
2 moderation 2026/08/13 03:15 Discussion d25bd376-be2e-491a-a0a7-ef39dc13a9a5
1 moderation 2026/08/12 13:25 Discussion 78f30cbc-93e5-4bed-a5bc-32f4877252b1
✨ AI Jobs (6)
ID Workflow Result Correct Bug Created Started Finished Revision
29771462 patch-iteration WARNING in futex_hash_allocate 2026/08/13 06:30 2026/08/13 06:30 2026/08/13 06:32 67796a05
095e447b patch-iteration WARNING in futex_hash_allocate 2026/08/13 05:10 2026/08/13 05:10 2026/08/13 05:36 67796a05
89be9910 patch-iteration WARNING in futex_hash_allocate 2026/08/13 03:40 2026/08/13 03:40 2026/08/13 04:08 a56bc0a5
d25bd376 patch-iteration WARNING in futex_hash_allocate 2026/08/13 02:45 2026/08/13 02:45 2026/08/13 03:15 a56bc0a5
78f30cbc patching WARNING in futex_hash_allocate 2026/08/12 11:59 2026/08/12 11:59 2026/08/12 13:25 f8d35649
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 (3)
Title Replies (including bot) Last reply
[PATCH] futex: Fix might_sleep() warning in futex_pivot_pending() 2 (2) 2026/08/20 16:31
[PATCH] futex: Fix might_sleep() warning in futex_pivot_pending() 3 (3) 2026/08/17 07:29
[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 [<ffffffff819fc8fd>] prepare_to_wait_event+0x3dd/0x480 kernel/sched/wait.c:317
WARNING: kernel/sched/core.c:9124 at __might_sleep+0x92/0xf0 kernel/sched/core.c:9120, CPU#0: syz.0.17/5885
Modules linked in:
CPU: 0 UID: 0 PID: 5885 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__might_sleep+0xac/0xf0 kernel/sched/core.c:9120
Code: 00 00 48 89 3c 24 41 89 f5 4c 8d 35 6e d3 c4 0e 43 80 3c 3c 00 74 08 48 89 df e8 2f 8e 9e 00 48 8b 0b 4c 89 f7 89 ee 48 89 ca <67> 48 0f b9 3a 44 89 ee 48 8b 3c 24 eb b5 44 89 f1 80 e1 07 80 c1
RSP: 0018:ffffc900035afac0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88801f31b770 RCX: ffffffff819fc8fd
RDX: ffffffff819fc8fd RSI: 0000000000000002 RDI: ffffffff905ae310
RBP: 0000000000000002 R08: ffffc900035afc07 R09: 0000000000000000
R10: ffffc900035afbe0 R11: fffff520006b5f81 R12: 1ffff11003e636ee
R13: 000000000000026f R14: ffffffff905ae310 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888124f49000(0063) knlGS:00000000f6825b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f7425014 CR3: 0000000071ab4000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __mutex_lock_common kernel/locking/mutex.c:623 [inline]
 __mutex_lock+0x118/0x1550 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+0x7fb/0xf00 kernel/futex/core.c:1872
 __do_sys_prctl kernel/sys.c:2885 [inline]
 __se_sys_prctl+0x78c/0x1910 kernel/sys.c:2534
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x23e/0x6f0 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf702f0ec
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000f682550c EFLAGS: 00000206 ORIG_RAX: 00000000000000ac
RAX: ffffffffffffffda RBX: 000000000000004e RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	48 89 3c 24          	mov    %rdi,(%rsp)
   6:	41 89 f5             	mov    %esi,%r13d
   9:	4c 8d 35 6e d3 c4 0e 	lea    0xec4d36e(%rip),%r14        # 0xec4d37e
  10:	43 80 3c 3c 00       	cmpb   $0x0,(%r12,%r15,1)
  15:	74 08                	je     0x1f
  17:	48 89 df             	mov    %rbx,%rdi
  1a:	e8 2f 8e 9e 00       	call   0x9e8e4e
  1f:	48 8b 0b             	mov    (%rbx),%rcx
  22:	4c 89 f7             	mov    %r14,%rdi
  25:	89 ee                	mov    %ebp,%esi
  27:	48 89 ca             	mov    %rcx,%rdx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	44 89 ee             	mov    %r13d,%esi
  32:	48 8b 3c 24          	mov    (%rsp),%rdi
  36:	eb b5                	jmp    0xffffffed
  38:	44 89 f1             	mov    %r14d,%ecx
  3b:	80 e1 07             	and    $0x7,%cl
  3e:	80                   	.byte 0x80
  3f:	c1                   	.byte 0xc1

Crashes (2107):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/17 07:07 upstream dcb68831eac7 746171ee .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
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
2026/08/12 04:45 upstream f5bbbfec59b4 f8d35649 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/23 03:10 upstream 66fb95a52111 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in futex_hash_allocate
2026/08/22 23:05 upstream 66fb95a52111 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in futex_hash_allocate
2026/08/22 20:50 upstream 66fb95a52111 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in futex_hash_allocate
2026/08/22 19:05 upstream 26260251022f 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in futex_hash_allocate
2026/08/19 23:30 upstream bd5f485f3f02 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in futex_hash_allocate
2026/08/19 15:50 upstream bd5f485f3f02 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in futex_hash_allocate
2026/08/22 19:03 upstream 26260251022f 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in futex_hash_allocate
2026/08/29 00:56 upstream 818bebeb63dd 2f52988a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/28 16:35 upstream 818bebeb63dd 41d151d4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/28 16:35 upstream 818bebeb63dd 41d151d4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/28 12:03 upstream 818bebeb63dd 41d151d4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/28 09:32 upstream 818bebeb63dd e2fa417d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/28 03:11 upstream 818bebeb63dd e2fa417d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/28 00:54 upstream 818bebeb63dd e2fa417d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/27 23:10 upstream 818bebeb63dd e2fa417d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/27 21:49 upstream 818bebeb63dd e2fa417d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/27 19:33 upstream 818bebeb63dd c53a1b9c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/27 18:04 upstream 818bebeb63dd c53a1b9c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/27 17:13 upstream 818bebeb63dd c53a1b9c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/27 14:11 upstream 818bebeb63dd c53a1b9c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/27 13:12 upstream 818bebeb63dd c53a1b9c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/27 11:52 upstream 818bebeb63dd c53a1b9c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/27 11:21 upstream 818bebeb63dd c53a1b9c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/27 10:04 upstream 818bebeb63dd c53a1b9c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/27 00:02 upstream 818bebeb63dd a2b77b9e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/26 19:54 upstream 818bebeb63dd a2b77b9e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/26 15:20 upstream 818bebeb63dd a2b77b9e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/26 15:02 upstream 818bebeb63dd a2b77b9e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/26 09:51 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/26 09:45 upstream 818bebeb63dd 6a91adb4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/26 05:54 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/26 05:25 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/26 04:41 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/26 04:23 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/26 03:40 upstream 818bebeb63dd 6a91adb4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/26 02:16 upstream 818bebeb63dd 6a91adb4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/26 01:56 upstream 818bebeb63dd 6a91adb4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/26 00:51 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 23:40 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 23:39 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 17:29 upstream 818bebeb63dd a9a1fc32 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 14:03 upstream 818bebeb63dd a9a1fc32 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/25 13:27 upstream 818bebeb63dd a9a1fc32 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/25 13:10 upstream 818bebeb63dd a9a1fc32 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 11:56 upstream 818bebeb63dd a9a1fc32 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 08:37 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 08:37 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/25 05:48 upstream 818bebeb63dd 614e416a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/25 04:33 upstream 818bebeb63dd 614e416a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/25 03:23 upstream 818bebeb63dd 614e416a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in futex_hash_allocate
2026/08/25 01:57 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in futex_hash_allocate
2026/08/21 04:17 upstream 9d2ed026f031 1e72964b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in futex_hash_allocate
2026/08/24 10:51 linux-next 903c1cf6dff9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in futex_hash_allocate
2026/08/24 04:39 linux-next 903c1cf6dff9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in futex_hash_allocate
2026/08/22 17:17 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux master 26260251022f 1e72964b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64-compat WARNING in futex_hash_allocate
2026/08/16 17:36 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux master 3eb40771c00a 746171ee .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.