INFO: rcu detected stall in call_usermodehelper_exec_async (4)

Status: upstream: reported C repro on 2025/11/27 14:55
Subsystems: mm
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+be81254ae29faa71cdfe@syzkaller.appspotmail.com
First crash: 432d, last: 11d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
733f030e assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in call_usermodehelper_exec_async (4) 2026/06/01 04:41 2026/06/01 04:41 2026/06/01 05:40 6b4a8443
6790da8f assessment-security 💥 INFO: rcu detected stall in call_usermodehelper_exec_async (4) 2026/05/15 10:21 2026/05/15 10:21 2026/05/15 10:22 9cd3beaa
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [udf?] INFO: rcu detected stall in call_usermodehelper_exec_async (4) 0 (1) 2025/11/27 14:55
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in call_usermodehelper_exec_async (2) 1 1 410d 410d 0/3 auto-obsoleted due to no activity on 2025/10/01 17:46
linux-6.1 INFO: rcu detected stall in call_usermodehelper_exec_async 1 1 790d 790d 0/3 auto-obsoleted due to no activity on 2024/09/16 03:00
upstream INFO: rcu detected stall in call_usermodehelper_exec_async mm 1 1 2440d 2440d 0/29 closed as invalid on 2019/12/04 14:14
linux-6.1 INFO: rcu detected stall in call_usermodehelper_exec_async (3) 1 1 59d 59d 0/3 upstream: reported on 2026/06/09 01:12
linux-5.15 INFO: rcu detected stall in call_usermodehelper_exec_async 1 1 1133d 1133d 0/3 auto-obsoleted due to no activity on 2023/10/09 16:55
upstream INFO: rcu detected stall in call_usermodehelper_exec_async (3) mm 1 23 540d 1036d 0/29 auto-obsoleted due to no activity on 2025/05/14 21:52
upstream INFO: rcu detected stall in call_usermodehelper_exec_async (2) cgroups mm 1 1 1530d 1530d 0/29 auto-closed as invalid on 2022/08/28 20:38
upstream BUG: soft lockup in call_usermodehelper_exec_async mm 1 2 1735d 1785d 0/29 closed as dup on 2021/09/17 07:37
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/12/07 22:22 37m retest repro linux-next OK log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6610/1:b.el
rcu: 	(detected by 1, t=10504 jiffies, g=21225, q=2815 ncpus=2)
task:modprobe        state:R  running task     stack:24776 pid:6610  tgid:6610  ppid:12     task_flags:0x400000 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:trace_lock_acquire include/trace/events/lock.h:23 [inline]
RIP: 0010:lock_acquire+0x61/0x350 kernel/locking/lockdep.c:5831
Code: 24 58 0f 1f 44 00 00 65 8b 05 2f 6c ca 11 83 f8 08 0f 83 83 01 00 00 89 c0 48 0f a3 05 18 dd b4 0e 73 0d e8 f1 29 09 00 84 c0 <0f> 84 ca 01 00 00 83 3d 12 10 b5 0e 00 0f 84 d3 00 00 00 48 8b b4
RSP: 0018:ffffc9000ffeedc0 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8c4bdc60 RDI: ffffffff8c4bdc20
RBP: ffffffff8177827f R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff81b1fa10 R12: 0000000000000002
R13: ffffffff8eb59c60 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:840 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
 unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
 alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
 alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
 pagetable_alloc_noprof include/linux/mm.h:3685 [inline]
 __pud_alloc_one_noprof include/asm-generic/pgalloc.h:181 [inline]
 pud_alloc_one_noprof include/asm-generic/pgalloc.h:206 [inline]
 __pud_alloc+0x3a/0x460 mm/memory.c:6748
 pud_alloc include/linux/mm.h:3595 [inline]
 __handle_mm_fault mm/memory.c:6439 [inline]
 handle_mm_fault+0x1f85/0x3080 mm/memory.c:6686
 do_user_addr_fault+0x744/0x1340 arch/x86/mm/fault.c:1394
 handle_page_fault arch/x86/mm/fault.c:1483 [inline]
 exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0010:__clear_user arch/x86/include/asm/uaccess_64.h:190 [inline]
RIP: 0010:clear_user arch/x86/include/asm/uaccess_64.h:207 [inline]
RIP: 0010:padzero fs/binfmt_elf.c:134 [inline]
RIP: 0010:elf_load+0x4b7/0x6a0 fs/binfmt_elf.c:436
Code: 8d 6f 20 eb 7a 41 be 00 10 00 00 4d 29 ee 48 c7 c7 d6 22 26 8e be b7 00 00 00 e8 34 2c b4 ff 0f 01 cb 31 c0 4c 89 e7 4c 89 f1 <f3> aa 0f 1f 00 49 89 ce 0f 01 ca 31 ff 48 89 ce e8 54 57 5f ff 8b
RSP: 0018:ffffc9000ffefa08 EFLAGS: 00050246
RAX: 0000000000000000 RBX: 00005574c2550010 RCX: 0000000000000ff8
RDX: 0000000000000000 RSI: ffffffff8e4b28e4 RDI: 00005574c2550008
RBP: dffffc0000000000 R08: ffffffff821bde4f R09: 0000000000000000
R10: 0000000000000000 R11: ffff88801b057678 R12: 00005574c2550008
R13: 0000000000000008 R14: 0000000000000ff8 R15: ffff888031713918
 load_elf_binary+0x116f/0x2950 fs/binfmt_elf.c:1188
 search_binary_handler fs/exec.c:1694 [inline]
 exec_binprm fs/exec.c:1726 [inline]
 bprm_execve+0x9c7/0x1630 fs/exec.c:1778
 kernel_execve+0x8c3/0x9c0 fs/exec.c:1922
 call_usermodehelper_exec_async+0x20f/0x360 kernel/umh.c:109
 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>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10503 jiffies! g21225 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=5852
rcu: rcu_preempt kthread starved for 10504 jiffies! g21225 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27496 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7326
 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
 kthread+0x388/0x470 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>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5614 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:qdisc_dev include/net/sch_generic.h:612 [inline]
RIP: 0010:taprio_set_budgets+0x60/0x3a0 net/sched/sch_taprio.c:666
Code: 80 3c 20 00 74 08 4c 89 ff e8 dc 6f 56 f8 4d 8b 3f 49 83 c7 40 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 <74> 08 4c 89 ff e8 b6 6f 56 f8 4d 8b 3f 4c 89 f8 48 c1 e8 03 48 b9
RSP: 0018:ffffc90000007ca8 EFLAGS: 00000046
RAX: 1ffff110036f2008 RBX: ffff88801b790280 RCX: dffffc0000000000
RDX: 0000000000010000 RSI: ffff8880546e2800 RDI: ffff88801b790280
RBP: ffff8880546e2800 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f90 R12: dffffc0000000000
R13: ffff88801b790000 R14: ffff88801b790280 R15: ffff88801b790040
FS:  0000000000000000(0000) GS:ffff888124f4e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005574c2550008 CR3: 0000000033a3b000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 advance_sched+0x970/0xc80 net/sched/sch_taprio.c:984
 __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
 __hrtimer_run_queues+0x3bc/0xa10 kernel/time/hrtimer.c:2096
 hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216
Code: 8b 3d 54 bc 88 0c 48 89 de 5b e9 23 0b 62 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d f8 1b a6 11 65 8b 15 19 1c a6 11 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90003167358 EFLAGS: 00000246
RAX: ffffffff8219923e RBX: ffff8880330da640 RCX: ffff888035e08000
RDX: 8000000057fad027 RSI: 00007fce38da6000 RDI: ffff8880705778c0
RBP: ffffc90003167690 R08: ffffea00015feb33 R09: 1ffffd40002bfd66
R10: dffffc0000000000 R11: fffff940002bfd67 R12: dffffc0000000000
R13: ffff8880705778c0 R14: ffff88807057bd30 R15: 8000000057fad027
 vm_normal_page+0x1e/0x280 mm/memory.c:769
 zap_present_ptes mm/memory.c:1700 [inline]
 do_zap_pte_range mm/memory.c:1832 [inline]
 zap_pte_range mm/memory.c:1934 [inline]
 zap_pmd_range mm/memory.c:2020 [inline]
 zap_pud_range mm/memory.c:2048 [inline]
 zap_p4d_range mm/memory.c:2069 [inline]
 __zap_vma_range+0x1091/0x4f10 mm/memory.c:2109
 unmap_vmas+0x390/0x550 mm/memory.c:2178
 exit_mmap+0x293/0x9f0 mm/mmap.c:1300
 __mmput+0x118/0x420 kernel/fork.c:1187
 exit_mm+0x221/0x2d0 kernel/exit.c:615
 do_exit+0x6cd/0x2360 kernel/exit.c:997
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
 get_signal+0x121b/0x12c0 kernel/signal.c:3046
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x104/0x730 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fce39b59017
Code: Unable to access opcode bytes at 0x7fce39b58fed.
RSP: 002b:00007ffced3ee2b0 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 000055555c66f500 RCX: 00007fce39b59017
RDX: 0000000040000000 RSI: 00007ffced3ee30c RDI: ffffffffffffffff
RBP: 00007ffced3ee30c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffced3ee568 R15: 0000000000000000
 </TASK>

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/27 07:21 upstream 4235cb24ec1e 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in call_usermodehelper_exec_async
2026/07/11 15:21 upstream d96fcfe1b7f9 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in call_usermodehelper_exec_async
2026/07/04 05:36 upstream 71dfdfb0209b fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in call_usermodehelper_exec_async
2026/03/27 19:54 upstream 46b513250491 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in call_usermodehelper_exec_async
2026/03/07 18:48 upstream 4ae12d8bd9a8 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in call_usermodehelper_exec_async
2025/11/08 20:08 upstream e811c33b1f13 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in call_usermodehelper_exec_async
2025/10/30 20:52 upstream e53642b87a4f fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in call_usermodehelper_exec_async
2025/08/19 15:22 upstream be48bcf004f9 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in call_usermodehelper_exec_async
2025/07/19 17:01 upstream 4871b7cb27f4 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in call_usermodehelper_exec_async
2025/07/11 04:54 upstream bc9ff192a6c9 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in call_usermodehelper_exec_async
2025/06/01 16:48 upstream 7d4e49a77d99 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in call_usermodehelper_exec_async
2026/07/13 20:44 net 3f1f75536668 a870962e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in call_usermodehelper_exec_async
2026/06/23 16:19 net a986fde914d8 4b1d8f01 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in call_usermodehelper_exec_async
2026/06/07 03:51 net 9772589b57e4 cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in call_usermodehelper_exec_async
2026/05/31 00:49 net 78ef59e7a645 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in call_usermodehelper_exec_async
2025/12/31 03:21 net 1adaea51c61b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in call_usermodehelper_exec_async
2025/11/23 14:41 linux-next d724c6f85e80 4fb8ef37 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in call_usermodehelper_exec_async
* Struck through repros no longer work on HEAD.