rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P15689/1:b..l rcu: (detected by 0, t=10505 jiffies, g=90193, q=320 ncpus=2) task:modprobe state:R running task stack:22624 pid:15689 tgid:15689 ppid:6034 task_flags:0x40000c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7276 preempt_schedule_notrace+0x56/0x90 kernel/sched/core.c:7548 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13 class_preempt_notrace_destructor include/linux/preempt.h:497 [inline] perf_trace_lock+0x38d/0x410 include/trace/events/lock.h:49 __do_trace_lock_release include/trace/events/lock.h:68 [inline] trace_lock_release include/trace/events/lock.h:68 [inline] lock_release+0x396/0x3c0 kernel/locking/lockdep.c:5954 rcu_lock_release include/linux/rcupdate.h:319 [inline] rcu_read_unlock include/linux/rcupdate.h:880 [inline] class_rcu_destructor include/linux/rcupdate.h:1216 [inline] unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x321/0x600 mm/slub.c:5563 _kmalloc_noprof include/linux/slab.h:991 [inline] slab_free_hook mm/slub.c:2700 [inline] slab_free mm/slub.c:6499 [inline] kmem_cache_free+0x156/0x650 mm/slub.c:6626 tear_down_vmas+0x31f/0x530 mm/mmap.c:1277 exit_mmap+0x4ca/0x9f0 mm/mmap.c:1335 __mmput+0x118/0x420 kernel/fork.c:1193 exit_mm+0x221/0x2d0 kernel/exit.c:614 do_exit+0x6cd/0x2360 kernel/exit.c:996 do_group_exit+0x22d/0x2f0 kernel/exit.c:1151 __do_sys_exit_group kernel/exit.c:1162 [inline] __se_sys_exit_group kernel/exit.c:1160 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1160 x64_sys_call+0x18c6/0x18d0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff503f2b6c5 RSP: 002b:00007fff931ba398 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007ff50402cfe8 RCX: 00007ff503f2b6c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000001 RBP: 0000000000000001 R08: 00007fff931ba328 R09: 0000000000000000 R10: 00007fff931ba1c0 R11: 0000000000000202 R12: 0000000000000000 R13: 0000000000000001 R14: 00007ff50402b680 R15: 00007ff50402d000 rcu: rcu_preempt kthread starved for 10503 jiffies! g90193 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:27648 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7276 __schedule_loop kernel/sched/core.c:7353 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7368 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2330 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 6012 Comm: kworker/u8:45 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: events_unbound nsim_dev_trap_report_work RIP: 0010:lock_is_held_type+0x106/0x150 kernel/locking/lockdep.c:6021 Code: 1b 00 00 b8 ff ff ff ff 65 0f c1 05 dc bc af 07 83 f8 01 75 25 9c 58 a9 00 02 00 00 75 39 41 f7 c4 00 02 00 00 74 01 fb 89 d8 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 5b 01 03 00 cc 90 0f 0b 90 48 c7 RSP: 0018:ffffc90006267120 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff8e6feed1 RDI: ffffffff8c6da480 RBP: 00000000ffffffff R08: ffffffff81ed6f89 R09: 0000000000000000 R10: ffffc900062672c0 R11: ffffffffa0400a18 R12: 0000000000000246 R13: ffff88802a4a5dc0 R14: ffffffff8ed5c920 R15: 0000000000000004 FS: 0000000000000000(0000) GS:ffff888124cd5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c26a411 CR3: 000000007e626000 CR4: 00000000003526f0 DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: lock_is_held include/linux/lockdep.h:249 [inline] rcu_read_lock_any_held+0x33/0x90 kernel/rcu/update.c:386 __rht_ptr_rcu include/linux/rhashtable.h:389 [inline] __rhashtable_lookup include/linux/rhashtable.h:632 [inline] rhashtable_lookup_likely include/linux/rhashtable.h:683 [inline] rhtab_lookup_elem+0x2d3/0xd90 kernel/bpf/hashtab.c:2909 rhtab_map_delete_elem+0xc6/0x190 kernel/bpf/hashtab.c:2973 bpf_prog_a4f1e23443ac9f8e+0x4e/0x56 bpf_dispatcher_nop_func include/linux/bpf.h:1483 [inline] __bpf_prog_run include/linux/filter.h:779 [inline] bpf_prog_run include/linux/filter.h:786 [inline] bpf_prog_run_array include/linux/bpf.h:2635 [inline] trace_call_bpf+0x3f1/0xb80 kernel/trace/bpf_trace.c:147 perf_trace_run_bpf_submit+0x78/0x170 kernel/events/core.c:11430 do_perf_trace_lock include/trace/events/lock.h:49 [inline] perf_trace_lock+0x32e/0x410 include/trace/events/lock.h:49 __do_trace_lock_release include/trace/events/lock.h:68 [inline] trace_lock_release include/trace/events/lock.h:68 [inline] lock_release+0x396/0x3c0 kernel/locking/lockdep.c:5954 rcu_lock_release include/linux/rcupdate.h:319 [inline] rcu_read_unlock include/linux/rcupdate.h:880 [inline] class_rcu_destructor include/linux/rcupdate.h:1216 [inline] unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709 __unwind_start+0x514/0x660 arch/x86/kernel/unwind_orc.c:787 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0xe3/0x150 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6499 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6626 nsim_dev_trap_report drivers/net/netdevsim/dev.c:817 [inline] nsim_dev_trap_report_work+0x7ac/0xb40 drivers/net/netdevsim/dev.c:847 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245