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: 587d, last: 1h00m
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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 767d 767d 0/29 auto-obsoleted due to no activity on 2024/11/17 09:26
upstream INFO: rcu detected stall in khugepaged mm 1 1 1477d 1477d 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 102d 102d 0/2 auto-obsoleted due to no activity on 2026/09/24 00:14

Sample crash report:
net_ratelimit: 26 callbacks suppressed
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P39/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=30117, q=3145 ncpus=2)
task:khugepaged      state:R  running task     stack:27664 pid:39    tgid:39    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:clear_pages arch/x86/include/asm/page_64.h:103 [inline]
RIP: 0010:clear_page arch/x86/include/asm/page_64.h:114 [inline]
RIP: 0010:clear_user_page include/linux/highmem.h:217 [inline]
RIP: 0010:clear_user_highpage include/linux/highmem.h:265 [inline]
RIP: 0010:__collapse_huge_page_copy+0x1f0/0xc70 mm/khugepaged.c:964
Code: 24 08 42 80 3c 28 00 74 0c 48 c7 c7 00 0f 6e 8e e8 75 15 f9 ff 48 c1 e3 06 48 03 1d 0a 44 2f 0c b9 00 10 00 00 31 c0 48 89 df <f3> aa 0f 1f 44 00 00 e9 bc 00 00 00 e8 ef 10 89 ff 48 b8 ff ff ff
RSP: 0018:ffffc90000af7748 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88804b03c000 RCX: 0000000000000f80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88804b03c080
RBP: ffffea00012c0000 R08: ffff888012f2dfff R09: 1ffff110025e5bff
R10: dffffc0000000000 R11: ffffed10025e5c00 R12: 000000000000003d
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000009
 collapse_huge_page mm/khugepaged.c:1421 [inline]
 mthp_collapse mm/khugepaged.c:1532 [inline]
 collapse_scan_pmd mm/khugepaged.c:1781 [inline]
 collapse_single_pmd+0x2ea7/0x3c50 mm/khugepaged.c:2797
 collapse_scan_mm_slot mm/khugepaged.c:2912 [inline]
 khugepaged_do_scan mm/khugepaged.c:2992 [inline]
 khugepaged+0xa00/0x1780 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 (37):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
2026/08/24 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.