syzbot

 sign-in | mailing list | source | docs
🐞 Open [825]
🐞 Fixed [84]
🐞 Invalid [1039]
⬇ Missing Backports [127]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in mmap_pgoff (3)

Status: upstream: reported on 2025/09/22 21:57
Reported-by: syzbot+7ed811a7f17b58c8cdcd@syzkaller.appspotmail.com
First crash: 18d, last: 3d23h
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in mmap_pgoff (6) fs 1 6 386d 482d 0/29 auto-obsoleted due to no activity on 2024/12/18 09:17
upstream INFO: rcu detected stall in mmap_pgoff (5) mm fs 1 2 806d 836d 0/29 auto-obsoleted due to no activity on 2023/10/25 16:56
linux-4.19 INFO: rcu detected stall in mmap_pgoff 1 syz error 2 1633d 1702d 0/1 upstream: reported syz repro on 2021/02/11 18:33
linux-5.15 INFO: rcu detected stall in mmap_pgoff 1 1 732d 732d 0/3 auto-obsoleted due to no activity on 2024/01/17 20:08
linux-5.15 INFO: rcu detected stall in mmap_pgoff (2) 1 10 158d 464d 0/3 auto-obsoleted due to no activity on 2025/08/14 00:27
upstream INFO: rcu detected stall in mmap_pgoff (4) mm 1 1 934d 934d 0/29 auto-obsoleted due to no activity on 2023/05/21 07:37
upstream INFO: rcu detected stall in mmap_pgoff crypto 1 3 1427d 1435d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in mmap_pgoff (3) mm 1 1 1124d 1124d 0/29 auto-obsoleted due to no activity on 2022/12/11 19:43
upstream INFO: rcu detected stall in mmap_pgoff (2) kernel 1 1 1323d 1323d 0/29 auto-closed as invalid on 2022/05/26 19:52

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P12700/1:b..l
	(detected by 0, t=10502 jiffies, g=48753, q=1905)
task:syz.5.2333      state:R  running task     stack:26592 pid:12700 ppid:  6400 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
 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:__sanitizer_cov_trace_pc+0x41/0x60 kernel/kcov.c:211
Code: ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00 00 74 2c 8b 91 10 16 00 00 83 fa 02 75 21 48 8b 91 18 16 00 00 48 8b 32 <48> 8d 7e 01 8b 89 14 16 00 00 48 39 cf 73 08 48 89 44 f2 08 48 89
RSP: 0018:ffffc900037df758 EFLAGS: 00000246
RAX: ffffffff819d9236 RBX: ffffea00019da240 RCX: ffff888061f78000
RDX: ffffc90017024000 RSI: 000000000001b525 RDI: 0000000000000000
RBP: ffffc900037df8d0 R08: dffffc0000000000 R09: fffff9400033b449
R10: fffff9400033b449 R11: 1ffffd400033b448 R12: 0000000000000000
R13: 0000000063dd9007 R14: ffffea00019da240 R15: ffffc900037df9c8
 filemap_map_pmd mm/filemap.c:3212 [inline]
 filemap_map_pages+0x3c6/0x1390 mm/filemap.c:3318
 do_fault_around mm/memory.c:4243 [inline]
 do_read_fault mm/memory.c:4258 [inline]
 do_fault mm/memory.c:4392 [inline]
 handle_pte_fault mm/memory.c:4650 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x2580/0x43c0 mm/memory.c:4883
 faultin_page mm/gup.c:976 [inline]
 __get_user_pages+0x93e/0x11c0 mm/gup.c:1197
 populate_vma_page_range+0x213/0x290 mm/gup.c:1529
 __mm_populate+0x26f/0x3a0 mm/gup.c:1638
 mm_populate include/linux/mm.h:2646 [inline]
 vm_mmap_pgoff+0x203/0x2b0 mm/util.c:556
 ksys_mmap_pgoff+0x140/0x780 mm/mmap.c:1635
 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: 0033:0x7f624b018ec9
RSP: 002b:00007f6249280038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f624b26ffa0 RCX: 00007f624b018ec9
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f624b09bf91 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f624b270038 R14: 00007f624b26ffa0 R15: 00007ffe7e5fc398
 </TASK>
rcu: rcu_preempt kthread starved for 10372 jiffies! g48753 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:28032 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 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 0
CPU: 0 PID: 12706 Comm: syz.0.2344 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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:3936 [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:1685 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 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 ef b8 c7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900033dfcb0 EFLAGS: 00000246
RAX: 00000000000000f6 RBX: ffffffff8bbc2a20 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed10172067af
R10: ffffed10172067af R11: 1ffff110172067ae R12: ffff8880b9033b01
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+0x38/0x244
 bpf_dispatcher_nop_func include/linux/bpf.h:888 [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: 0033:0x7f4295d5dec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4293fa40e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f4295fb5098 RCX: 00007f4295d5dec9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f4295fb5098
RBP: 00007f4295fb5090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4295fb5128 R14: 00007ffe14d3c0c0 R15: 00007ffe14d3c1a8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/07 08:50 linux-5.15.y 29e53a5b1c4f 8ef35d49 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in mmap_pgoff
2025/09/22 21:56 linux-5.15.y 43bb85222e53 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in mmap_pgoff
* Struck through repros no longer work on HEAD.