INFO: rcu detected stall in proc_reg_read_iter

Status: auto-obsoleted due to no activity on 2025/10/05 00:54
Reported-by: syzbot+72d442db9128d49381f9@syzkaller.appspotmail.com
First crash: 417d, last: 417d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in proc_reg_read_iter (3) prio:high mm 1 2 167d 223d 0/29 auto-obsoleted due to no activity on 2026/06/02 09:49
upstream INFO: rcu detected stall in proc_reg_read_iter fs 1 1 978d 978d 0/29 auto-obsoleted due to no activity on 2024/03/13 15:35
upstream INFO: rcu detected stall in proc_reg_read_iter (2) mm 1 1 353d 353d 0/29 auto-obsoleted due to no activity on 2025/11/28 17:40

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9622/1:b..l
	(detected by 1, t=10502 jiffies, g=39945, q=4)
task:modprobe        state:R  running task     stack:27680 pid: 9622 ppid:  7018 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6780
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x32/0x80 kernel/kcov.c:293
Code: 34 aa 8a 7e 65 8b 15 35 aa 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 5b 83 b9 34 16 00 00 00 74 52 8b 91 10 16 00 00 <83> fa 03 75 47 48 8b 91 18 16 00 00 44 8b 89 14 16 00 00 49 c1 e1
RSP: 0018:ffffc900043bfb30 EFLAGS: 00000246
RAX: ffffffff81355a69 RBX: 0000000000000001 RCX: ffff88807d109dc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff1ff3619
R10: fffffbfff1ff3619 R11: 1ffffffff1ff3618 R12: 0000000000000008
R13: 0000000000000001 R14: ffff88813fffa060 R15: dffffc0000000000
 rcu_read_unlock include/linux/rcupdate.h:768 [inline]
 pfn_valid include/linux/mmzone.h:1510 [inline]
 __virt_addr_valid+0x349/0x470 arch/x86/mm/physaddr.c:65
 check_heap_object mm/usercopy.c:228 [inline]
 __check_object_size+0xa8/0x410 mm/usercopy.c:286
 check_object_size include/linux/thread_info.h:199 [inline]
 check_copy_size include/linux/thread_info.h:232 [inline]
 copy_to_iter include/linux/uio.h:152 [inline]
 seq_read_iter+0xb6b/0xd50 fs/seq_file.c:281
 proc_reg_read_iter+0x1a9/0x270 fs/proc/inode.c:300
 call_read_iter include/linux/fs.h:2166 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x725/0xcf0 fs/read_write.c:485
 ksys_read+0x14d/0x250 fs/read_write.c:623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f89bf1da407
RSP: 002b:00007ffd3ccd0be0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f89bf08ac80 RCX: 00007f89bf1da407
RDX: 0000000000000400 RSI: 000056395ffe2500 RDI: 0000000000000000
RBP: 00007f89bf322ff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffd3ccd0cc8
R13: 00007f89bf322ea0 R14: 00007f89bf1264d0 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10525 jiffies! g39945 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:R  running task     stack:27008 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 9613 Comm: syz.2.1375 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1690 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:212 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:156 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:263 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:208
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 9f 6c c8 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc90002f3fcb0 EFLAGS: 00000246
RAX: 00000000000000f6 RBX: ffffffff8bbafa10 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed10172267a7
R10: ffffed10172267a7 R11: 1ffff110172267a6 R12: ffff8880b9133b01
R13: dffffc0000000000 R14: dffffc0000000000 R15: 0000000000000020
 arch_irq_work_raise+0x82/0xd0 arch/x86/kernel/irq_work.c:31
 irq_work_queue+0x95/0x140 kernel/irq_work.c:75
 bpf_send_signal_common+0x2b2/0x420 kernel/trace/bpf_trace.c:820
 ____bpf_send_signal kernel/trace/bpf_trace.c:829 [inline]
 bpf_send_signal+0x15/0x20 kernel/trace/bpf_trace.c:827
 bpf_prog_7ba5217f62dcd359+0x38/0x8d8
 bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline]
 __bpf_prog_run include/linux/filter.h:628 [inline]
 bpf_prog_run include/linux/filter.h:635 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline]
 bpf_trace_run2+0x15b/0x2d0 kernel/trace/bpf_trace.c:1915
 __bpf_trace_sys_enter+0x60/0x70 include/trace/events/syscalls.h:18
 trace_sys_enter+0x65/0x80 include/trace/events/syscalls.h:18
 syscall_trace_enter+0x115/0x180 kernel/entry/common.c:77
 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f04a1f5ab19
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f049fe25b40 EFLAGS: 00000246 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f04a21e5fa8 RCX: 00007f04a1f5ab19
RDX: 00007f049fe25b40 RSI: 00007f049fe25c70 RDI: 0000000000000011
RBP: 00007f04a21e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f04a21e5fac
R13: 0000000000000000 R14: 00007ffccee01710 R15: 00007ffccee017f8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/27 00:54 linux-5.15.y 1c700860e8bc 803ce19b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in proc_reg_read_iter
* Struck through repros no longer work on HEAD.