INFO: rcu detected stall in asm_exc_page_fault

Status: upstream: reported C repro on 2026/09/05 19:18
Reported-by: syzbot+5217fb29b57f3f486673@syzkaller.appspotmail.com
First crash: 1d00h, last: 1d00h
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in asm_exc_page_fault (2) kasan mm 1 1 317d 317d 0/29 auto-obsoleted due to no activity on 2026/01/22 14:37
linux-5.15 INFO: rcu detected stall in asm_exc_page_fault 1 1 228d 228d 0/3 auto-obsoleted due to no activity on 2026/05/01 14:57
upstream INFO: rcu detected stall in asm_exc_page_fault mm 1 syz error error 4 521d 911d 0/29 auto-obsoleted due to no activity on 2025/07/30 11:21
linux-6.6 INFO: rcu detected stall in asm_exc_page_fault 1 2 14d 49d 0/2 upstream: reported on 2026/07/19 00:59
android-5-15 BUG: soft lockup in asm_exc_page_fault 1 syz, C error 3 735d 883d 0/2 auto-obsoleted due to no activity on 2024/12/10 17:09

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P4344 0-.... } 2704 jiffies s: 897 root: 0x1/T
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4368 Comm: syz-executor905 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_preemption_disabled+0x1f/0x110 lib/smp_processor_id.c:16
Code: df 8a 48 c7 c6 00 64 df 8a eb 00 55 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65 8b 05 d1 bc d0 75 <65> 8b 0d 72 12 d1 75 f7 c1 ff ff ff 7f 74 1f 65 48 8b 0c 25 28 00
RSP: 0018:ffffc90000007568 EFLAGS: 00000082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 1a50727bd3387200
RDX: 0000000000000100 RSI: ffffffff8adf6400 RDI: ffffffff8adf63c0
RBP: ffffc90000007668 R08: ffffffff8e2116af R09: 1ffffffff1c422d5
R10: dffffc0000000000 R11: fffffbfff1c422d6 R12: dffffc0000000000
R13: 0000000000000000 R14: ffff8880b8e357c0 R15: 0000000000000002
FS:  00007f9a18c5c6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055878931a848 CR3: 000000007834a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 ct_dynticks include/linux/context_tracking_state.h:61 [inline]
 ct_nmi_enter+0xda/0x170 kernel/context_tracking.c:299
 ct_irq_enter_irqson+0xaf/0x170 kernel/context_tracking.c:407
 trace_irq_enable_rcuidle+0x9f/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 12 6c 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007760 EFLAGS: 00000206
RAX: 1a50727bd3387200 RBX: 1ffff92000000ef4 RCX: 1a50727bd3387200
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: ffffffff8adf6420
RBP: ffffc90000007860 R08: ffffffff90b13337 R09: 1ffffffff2162666
R10: dffffc0000000000 R11: fffffbfff2162667 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8e3bb00 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 ndisc_send_skb+0xdc2/0x1520 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x367/0x640 net/ipv6/addrconf.c:3986
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:preempt_schedule_irq+0xb6/0x160 kernel/sched/core.c:6875
Code: 00 00 43 c6 44 37 04 f8 74 0b 0f 0b 48 f7 03 08 00 00 00 74 7f bf 01 00 00 00 e8 45 e2 1e f7 e8 b0 bf 4e f7 fb bf 01 00 00 00 <e8> 25 ba ff ff 43 c6 44 37 08 00 48 c7 44 24 40 00 00 00 00 9c 8f
RSP: 0018:ffffc900045f7a60 EFLAGS: 00000286
RAX: 1a50727bd3387200 RBX: 0000000000000000 RCX: 1a50727bd3387200
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: 0000000000000001
RBP: ffffc900045f7b00 R08: ffff8880b8e357cb R09: 1ffff110171c6af9
R10: dffffc0000000000 R11: ffffed10171c6afa R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920008bef4c
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:preempt_count_sub+0x61/0x160 kernel/sched/core.c:5751
Code: ff ff ff 7f 39 cf 7f 25 81 ff ff 00 00 00 0f 93 c1 84 c0 0f 95 c0 08 c8 74 53 65 8b 05 b0 a0 a9 7e f7 df 65 01 3d a7 a0 a9 7e <5b> 5d c3 e8 17 09 ba 02 85 c0 74 f4 48 c7 c0 68 4b 21 8e 48 c1 e8
RSP: 0018:ffffc900045f7bc8 EFLAGS: 00000297
RAX: 0000000080000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000008 RDI: 00000000ffffffff
RBP: ffffc900045f7c98 R08: ffff88807817446f R09: 1ffff1100f02e88d
R10: dffffc0000000000 R11: ffffed100f02e88e R12: 0000000000000000
R13: 1ffff920008bef80 R14: dffffc0000000000 R15: 1ffff1100f02e88e
 __up_read+0x2b4/0x6b0 kernel/locking/rwsem.c:1356
 lock_mm_and_find_vma+0x107/0x2f0 mm/memory.c:5394
 do_user_addr_fault+0x2e8/0xb20 arch/x86/mm/fault.c:1310
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:__put_user_nocheck_4+0x3/0x11
Code: 00 00 48 39 d9 73 54 0f 01 cb 66 89 01 31 c9 0f 01 ca c3 90 90 90 90 90 48 bb fd ef ff ff ff 7f 00 00 48 39 d9 73 34 0f 01 cb <89> 01 31 c9 0f 01 ca c3 90 90 90 90 90 90 48 bb f9 ef ff ff ff 7f
RSP: 0018:ffffc900045f7e80 EFLAGS: 00050297
RAX: 0000000000000008 RBX: 00007fffffffeffd RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8a8c2a20 RDI: ffffffff8adf6420
RBP: 0000000000000008 R08: ffffffff8e2116af R09: 1ffffffff1c422d5
R10: dffffc0000000000 R11: fffffbfff1c422d6 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000005
 __sys_socketpair+0xb4/0x540 net/socket.c:1720
 __do_sys_socketpair net/socket.c:1786 [inline]
 __se_sys_socketpair net/socket.c:1783 [inline]
 __x64_sys_socketpair+0x97/0xb0 net/socket.c:1783
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9a194939c9
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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9a18c5c218 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007f9a1953c908 RCX: 00007f9a194939c9
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000001
RBP: 00007f9a1953c900 R08: 31203a6b63617473 R09: 31203a6b63617473
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9a19502d1c
R13: fffffffdffffffff R14: 0000200000000140 R15: 0000200000000480
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.775 msecs

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/05 19:17 linux-6.1.y cf82dcca9634 4f7b22a0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in asm_exc_page_fault
* Struck through repros no longer work on HEAD.