INFO: rcu detected stall in mmap_file (4)

Status: upstream: reported on 2026/06/14 00:35
Reported-by: syzbot+bde8280833fcc88121dd@syzkaller.appspotmail.com
First crash: 118d, last: 4d21h
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in mmap_file (3) 1 3 221d 392d 0/3 auto-obsoleted due to no activity on 2026/06/11 12:22
linux-5.15 INFO: rcu detected stall in mmap_file 1 1 657d 657d 0/3 auto-obsoleted due to no activity on 2025/04/01 14:21
linux-6.1 INFO: rcu detected stall in mmap_file 1 1 135d 135d 0/3 auto-obsoleted due to no activity on 2026/09/04 21:34
linux-5.15 INFO: rcu detected stall in mmap_file (2) 1 1 502d 502d 0/3 auto-obsoleted due to no activity on 2025/09/02 23:08
android-5-10 BUG: soft lockup in mmap_file 1 1 37d 37d 0/2 premoderation: reported on 2026/09/02 19:03

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=57d/1/0x4000000000000002 softirq=19398/19398 fqs=645 
	(detected by 1, t=10502 jiffies, g=28277, q=94)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9311 Comm: syz.2.1329 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:instrument_atomic_write include/linux/instrumented.h:86 [inline]
RIP: 0010:set_bit include/asm-generic/bitops/instrumented-atomic.h:28 [inline]
RIP: 0010:set_ti_thread_flag include/linux/thread_info.h:89 [inline]
RIP: 0010:set_tsk_thread_flag include/linux/sched.h:1983 [inline]
RIP: 0010:set_tsk_need_resched include/linux/sched.h:2014 [inline]
RIP: 0010:rcu_read_unlock_special+0x251/0x4a0 kernel/rcu/tree_plugin.h:659
Code: 0f 00 0f 85 4a 01 00 00 44 08 24 24 0f 84 40 01 00 00 4c 89 34 24 4c 8b 74 24 10 45 89 f5 41 c1 ed 09 65 4c 8b 3d 9f fa 9c 7e <4c> 89 ff be 08 00 00 00 e8 e2 f4 58 00 f0 41 80 0f 08 65 81 25 8a
RSP: 0018:ffffc9000304eb00 EFLAGS: 00000046
RAX: 0000000000000002 RBX: 1ffff92000609d64 RCX: dffffc0000000000
RDX: ffffc9000c651000 RSI: ffffffff8a7a4b60 RDI: ffffffff8a7a4b20
RBP: ffffc9000304ebe0 R08: ffffffff8d8b2bef R09: 1ffffffff1b1657d
R10: dffffc0000000000 R11: fffffbfff1b1657e R12: ffffffff8c323400
R13: 0000000000000000 R14: 0000000000000046 R15: ffff88802c41bb80
FS:  00007f92c8aca6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001300 CR3: 00000000599f2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 __perf_event_output kernel/events/core.c:7823 [inline]
 perf_event_output_forward+0x255/0x2e0 kernel/events/core.c:7832
 __perf_event_overflow+0x35f/0x550 kernel/events/core.c:9525
 perf_swevent_overflow kernel/events/core.c:9601 [inline]
 perf_swevent_event+0x4b8/0x540 kernel/events/core.c:9639
 perf_tp_event+0x324/0xbe0 kernel/events/core.c:10057
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
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 82 fc 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc9000304f2a0 EFLAGS: 00000206
RAX: bbd967c902007000 RBX: 1ffff92000609e58 RCX: bbd967c902007000
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4b80
RBP: ffffc9000304f380 R08: ffffffff902140c7 R09: 1ffffffff2042818
R10: dffffc0000000000 R11: fffffbfff2042819 R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 is_bpf_text_address+0x24f/0x270 kernel/bpf/core.c:727
 kernel_text_address kernel/extable.c:151 [inline]
 __kernel_text_address+0x9a/0x100 kernel/extable.c:105
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 adjust_va_to_fit_type mm/vmalloc.c:1343 [inline]
 __alloc_vmap_area mm/vmalloc.c:1459 [inline]
 alloc_vmap_area+0x157f/0x1b30 mm/vmalloc.c:1550
 __get_vm_area_node+0x14f/0x2d0 mm/vmalloc.c:2430
 __vmalloc_node_range+0xef/0x8b0 mm/vmalloc.c:3027
 __vmalloc_node mm/vmalloc.c:3087 [inline]
 __vmalloc+0x76/0x80 mm/vmalloc.c:3101
 bpf_prog_alloc_no_stats+0x36/0x2c0 kernel/bpf/core.c:90
 bpf_prog_alloc+0x1a/0x1e0 kernel/bpf/core.c:124
 bpf_prog_load+0x7d1/0x14e0 kernel/bpf/syscall.c:2301
 __sys_bpf+0x532/0x6f0 kernel/bpf/syscall.c:4657
 __do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
 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: 0033:0x7f92ca872199
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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f92c8aca028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f92caaf9fa0 RCX: 00007f92ca872199
RDX: 0000000000000080 RSI: 00002000000001c0 RDI: 0000000000000005
RBP: 00007f92ca9090b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f92caafa038 R14: 00007f92caaf9fa0 R15: 00007ffcd9382e88
 </TASK>
rcu: rcu_preempt kthread starved for 9210 jiffies! g28277 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:27504 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
 kthread+0x42e/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: 9314 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 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+0x1110/0x1270 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+0x845/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 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+0x4b0/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x397/0x8b0 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:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x159/0x1b0 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 4b 0f b6 1f e8 47 a5 4a 00 44 38 e3 75 10 66 90 0f 00 2d 89 d9 f3 08 fb f4 <e9> 16 ff ff ff fb e9 10 ff ff ff e8 b7 6c 8d 08 89 f9 80 e1 07 38
RSP: 0018:ffffc90002dcf600 EFLAGS: 00000246
RAX: 06da1c4be71a4000 RBX: 0000000000000003 RCX: 06da1c4be71a4000
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4b80
RBP: ffffc90002dcf6b0 R08: ffffffff902140c7 R09: 1ffffffff2042818
R10: dffffc0000000000 R11: fffffbfff2042819 R12: 0000000000000003
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff920005b9ec0
 pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x605/0x9b0 kernel/locking/qspinlock.c:508
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
 queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115
 spin_lock include/linux/spinlock.h:364 [inline]
 preload_this_cpu_lock mm/vmalloc.c:1507 [inline]
 alloc_vmap_area+0x677/0x1b30 mm/vmalloc.c:1549
 __get_vm_area_node+0x14f/0x2d0 mm/vmalloc.c:2430
 __vmalloc_node_range+0xef/0x8b0 mm/vmalloc.c:3027
 vmalloc_user+0x70/0x80 mm/vmalloc.c:3173
 kcov_mmap+0x27/0x120 kernel/kcov.c:479
 call_mmap include/linux/fs.h:2184 [inline]
 mmap_file+0x5d/0xb0 mm/util.c:1092
 __mmap_region mm/mmap.c:1796 [inline]
 mmap_region+0x1048/0x1730 mm/mmap.c:2933
 do_mmap+0x801/0xe30 mm/mmap.c:1586
 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:551
 ksys_mmap_pgoff+0x4e2/0x790 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: 0033:0x7f350f122f02
Code: 4f 01 00 0f 1f 44 00 00 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 3b 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 6e 5b 5d c3 0f 1f 00 48 c7 c0 e8 ff ff ff 64
RSP: 002b:00007fff0aadc248 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f350eb84000 RCX: 00007f350f122f02
RDX: 0000000000000003 RSI: 0000000000400000 RDI: 00007f350eb84000
RBP: 0000000000000011 R08: 00000000000000d8 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000206 R12: 0000000000000003
R13: 0000000000000003 R14: 00007fff0aadc4b8 R15: 0000000000000000
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/05 19:46 linux-5.15.y a051a4bf909f af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mmap_file
2026/08/27 00:12 linux-5.15.y 945fa863f02c a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mmap_file
2026/08/16 17:07 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mmap_file
2026/06/19 06:42 linux-5.15.y dc027a595035 a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in mmap_file
2026/06/14 00:35 linux-5.15.y dc027a595035 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mmap_file
* Struck through repros no longer work on HEAD.