INFO: rcu detected stall in khugepaged (3)

Status: upstream: reported on 2026/08/05 00:01
Subsystems: mm
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+d2401aeb74cc84adba04@syzkaller.appspotmail.com
First crash: 594d, last: 1d02h
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ID Workflow Result Correct Bug Created Started Finished Revision
4f1a87d0 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in khugepaged (3) 2026/05/23 06:14 2026/05/23 06:14 2026/05/23 07:17 c69befb3
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Title Replies (including bot) Last reply
[syzbot] [mm?] INFO: rcu detected stall in khugepaged (3) 6 (7) 2026/08/06 17:19
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in khugepaged (2) mm 1 1 774d 774d 0/29 auto-obsoleted due to no activity on 2024/11/17 09:26
upstream INFO: rcu detected stall in khugepaged mm 1 1 1484d 1484d 0/29 auto-obsoleted due to no activity on 2022/12/08 19:48
linux-6.6 INFO: rcu detected stall in khugepaged 1 1 109d 109d 0/2 auto-obsoleted due to no activity on 2026/09/24 00:14

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P38/1:b..l
rcu: 	(detected by 0, t=10503 jiffies, g=61781, q=1904 ncpus=2)
task:khugepaged      state:R  running task     stack:26864 pid:38    tgid:38    ppid:2      task_flags:0x200040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5533 [inline]
 __schedule+0x17db/0x58f0 kernel/sched/core.c:7284
 preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7606
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x910 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:rcu_read_lock include/linux/rcupdate.h:850 [inline]
RIP: 0010:start_flush_work kernel/workqueue.c:4354 [inline]
RIP: 0010:__flush_work+0x14f/0xca0 kernel/workqueue.c:4412
Code: 08 e8 05 15 58 0a 41 89 c7 31 ff 89 c6 e8 c9 59 39 00 45 85 ff 74 15 e8 af e4 1d 00 84 c0 74 18 e8 b6 54 39 00 4c 8b 7c 24 08 <eb> 67 e8 aa 54 39 00 4c 8b 7c 24 08 eb 5b e8 ce 14 58 0a 41 89 c7
RSP: 0018:ffffc90000ae7960 EFLAGS: 00000293
RAX: ffffffff818e967a RBX: ffff8880b8734108 RCX: ffff88802128ddc0
RDX: 0000000000000000 RSI: ffffffff8c6dad60 RDI: ffffffff8c6dad20
RBP: ffffc90000ae7b08 R08: ffffffff818e9631 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff20f4c50 R12: dffffc0000000000
R13: 1ffff110170e6821 R14: 1ffff9200015cf34 R15: ffff8880b87340f0
 __lru_add_drain_all+0x5eb/0x7a0 mm/folio.c:868
 khugepaged_do_scan mm/khugepaged.c:2978 [inline]
 khugepaged+0x1a7/0x1780 mm/khugepaged.c:3047
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (39):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/29 22:54 upstream 6f8319e3e9a4 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/09/26 04:43 upstream aa98230e410f f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/09/21 02:10 upstream 518e5b794c06 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/08/13 21:32 upstream 3d6d817622b0 a9ede23c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/08/06 10:46 upstream 0d8395707651 cc56899a .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2026/08/05 03:36 upstream c21bb4193868 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in khugepaged
2026/07/31 07:15 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/07/01 01:03 upstream dc59e4fea9d8 00e8b0fd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/06/16 19:43 upstream 6b5a2b7d9bc1 0e4b3e40 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in khugepaged
2026/05/06 23:08 upstream adc1e5c6203c cbcd9ea0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in khugepaged
2026/04/12 08:32 upstream e753c16cb3dd 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/04/01 02:57 upstream d0c3bcd5b897 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2026/02/15 02:26 upstream 3e48a11675c5 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2026/01/27 08:57 upstream fcb70a56f4d8 43e1df1d .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2026/01/17 00:39 upstream 39d3389331ab d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2026/01/13 01:22 upstream 0f61b1860cc3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2026/01/03 07:29 upstream 9b0436804460 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2026/01/01 16:07 upstream b69053dd3ffb d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/12/25 07:08 upstream ccd1cdca5cd4 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/12/07 11:06 upstream cc3ee4ba57b7 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/12/07 10:16 upstream cc3ee4ba57b7 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/12/04 09:43 upstream 8f7aa3d3c732 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/12/03 21:34 upstream 3f9f0252130e d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/11/27 01:23 upstream 30f09200cc4a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in khugepaged
2025/11/06 03:28 upstream dc77806cf3b4 a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/11/02 09:02 upstream 691d401c7e0e 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2025/10/08 04:10 upstream 971199ad2a0f 7e2882b3 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/08/04 20:27 upstream d2eedaa3909b f5bcc8dc .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/07/02 10:45 upstream 66701750d556 bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/06/22 02:10 upstream 3f75bfff44be d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2025/06/10 15:57 upstream f09079bd04a9 5d7e17ca .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2025/05/11 05:42 upstream 345030986df8 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in khugepaged
2025/05/07 13:12 upstream 0d8d44db295c 350f4ffc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in khugepaged
2025/02/15 23:27 upstream 7ff71e6d9239 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in khugepaged
2026/08/06 05:57 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: rcu detected stall in khugepaged
2026/04/21 20:46 upstream 4ee64205ffaa 0b6ab7ec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: rcu detected stall in khugepaged
2026/10/02 03:45 linux-next 9f24d789f03b 6d32eb1f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in khugepaged
2026/08/24 03:03 linux-next 903c1cf6dff9 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in khugepaged
2025/07/06 10:54 linux-next 26ffb3d6f02c 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in khugepaged
* Struck through repros no longer work on HEAD.