INFO: rcu detected stall in mmap_pgoff (4)

Status: upstream: reported on 2026/08/13 09:40
Reported-by: syzbot+3bfd2f5667b2c6829419@syzkaller.appspotmail.com
First crash: 8d08h, last: 8d08h
▶ ▼ Similar bugs (10)
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 701d 797d 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 1121d 1150d 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 1948d 2016d 0/1 upstream: reported syz repro on 2021/02/11 18:33
linux-5.15 INFO: rcu detected stall in mmap_pgoff 1 1 1046d 1046d 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 472d 778d 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 1248d 1248d 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 1741d 1749d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in mmap_pgoff (3) mm 1 1 1438d 1438d 0/29 auto-obsoleted due to no activity on 2022/12/11 19:43
linux-5.15 INFO: rcu detected stall in mmap_pgoff (3) 1 9 145d 332d 0/3 auto-obsoleted due to no activity on 2026/07/07 03:07
upstream INFO: rcu detected stall in mmap_pgoff (2) kernel 1 1 1637d 1637d 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): P10549/1:b..l P10546/1:b..l
	(detected by 0, t=10502 jiffies, g=58273, q=12)
task:syz.8.1327      state:R  running task     stack:25392 pid:10546 ppid:  5074 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 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:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90002f7f620 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: f7d867635a86b200
RDX: 0000000000000000 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a4200
RBP: ffffc90002f7f740 R08: dffffc0000000000 R09: 1ffffffff203dc18
R10: dffffc0000000000 R11: fffffbfff203dc19 R12: ffffffff8c31ef60
R13: 1ffff920005efed0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 filemap_map_pages+0x18e/0x1450 mm/filemap.c:3313
 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+0x25bb/0x4440 mm/memory.c:4883
 faultin_page mm/gup.c:976 [inline]
 __get_user_pages+0x952/0x11e0 mm/gup.c:1197
 populate_vma_page_range+0x213/0x290 mm/gup.c:1529
 __mm_populate+0x275/0x3b0 mm/gup.c:1638
 mm_populate include/linux/mm.h:2646 [inline]
 vm_mmap_pgoff+0x212/0x2d0 mm/util.c:556
 ksys_mmap_pgoff+0x140/0x790 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: 0033:0x7fcbbb4740d9
RSP: 002b:00007fcbb96cc028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fcbbb6fbfa0 RCX: 00007fcbbb4740d9
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007fcbbb50b024 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcbbb6fc038 R14: 00007fcbbb6fbfa0 R15: 00007fff18cacb18
 </TASK>
task:syz.3.1329      state:R  running task     stack:27280 pid:10549 ppid:  6953 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 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:css_tryget include/linux/cgroup.h:354 [inline]
RIP: 0010:get_mem_cgroup_from_objcg+0x99/0x120 mm/memcontrol.c:2815
Code: 80 7c 25 00 00 74 08 48 89 df e8 f2 e1 fa ff 4c 8b 33 4d 8d 7e 54 4c 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 75 15 41 f6 07 01 <75> 26 49 8d 7e 10 e8 bc fc ff ff 84 c0 75 19 eb c4 44 89 f9 80 e1
RSP: 0018:ffffc9000310f680 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888022768790 RCX: b93df426f19f6300
RDX: 0000000000000000 RSI: ffffffff8a7a41e0 RDI: ffffffff8a7a41a0
RBP: 0000000000000005 R08: dffffc0000000000 R09: 1ffffffff203dc18
R10: dffffc0000000000 R11: fffffbfff203dc19 R12: dffffc0000000000
R13: 1ffff110044ed0f2 R14: ffff88802a910000 R15: ffff88802a910054
 obj_cgroup_uncharge_pages mm/memcontrol.c:2992 [inline]
 __memcg_kmem_uncharge_page+0x74/0x140 mm/memcontrol.c:3083
 free_pages_prepare mm/page_alloc.c:1332 [inline]
 __free_pages_ok+0x1a0/0x950 mm/page_alloc.c:1643
 free_nonslab_page+0xde/0x150 mm/slub.c:3540
 kvm_set_memslot+0x1328/0x1a00 virt/kvm/kvm_main.c:1696
 __kvm_set_memory_region+0xb5e/0xd90 virt/kvm/kvm_main.c:1843
 kvm_set_memory_region virt/kvm/kvm_main.c:1864 [inline]
 kvm_vm_ioctl_set_memory_region+0x6f/0xa0 virt/kvm/kvm_main.c:1876
 kvm_vm_ioctl+0x8d7/0xb00 virt/kvm/kvm_main.c:4493
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 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: 0033:0x7ff179b45d6b
RSP: 002b:00007ff177d9c450 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007ff179b45d6b
RDX: 00007ff177d9cbd0 RSI: 000000004020ae46 RDI: 0000000000000004
RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000018
R10: 0000000000000004 R11: 0000000000000246 R12: 00000000fec00000
R13: 00007ff177d9cbd0 R14: 0000200000016000 R15: 0000000000000016
 </TASK>
rcu: rcu_preempt kthread starved for 10331 jiffies! g58273 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:27456 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 0
CPU: 0 PID: 10556 Comm: syz.5.1331 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 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+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0033:0x7f4cc1fa50d7
Code: 83 c8 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
RSP: 002b:00007f4cc01dc028 EFLAGS: 00000246
RAX: 0000000000000028 RBX: 00007f4cc222d090 RCX: 00007f4cc1fa50d9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f4cc203c024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000020000023896 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4cc222d128 R14: 00007f4cc222d090 R15: 00007ffff3d32018
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/13 09:40 linux-5.15.y aabd761612db 359b2492 .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.