rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7782/4:b..l P4979/1:b..l P11496/1:b..l rcu: (detected by 0, t=10502 jiffies, g=90553, q=788 ncpus=1) task:syz.8.1556 state:R running task stack:27256 pid:11496 tgid:11495 ppid:8320 task_flags:0x40044c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7413 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:190 spin_unlock include/linux/spinlock.h:390 [inline] zap_pte_range mm/memory.c:1964 [inline] zap_pmd_range mm/memory.c:2020 [inline] zap_pud_range mm/memory.c:2048 [inline] zap_p4d_range mm/memory.c:2069 [inline] __zap_vma_range+0x24b4/0x4a30 mm/memory.c:2109 unmap_vmas+0x299/0x5f0 mm/memory.c:2178 exit_mmap+0x1ef/0xa00 mm/mmap.c:1300 __mmput+0x12a/0x410 kernel/fork.c:1187 mmput+0x67/0x80 kernel/fork.c:1210 exit_mm kernel/exit.c:615 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:997 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152 get_signal+0x1ec7/0x21e0 kernel/signal.c:3046 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x139/0x6f0 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f235679e019 RSP: 002b:00007f23575a00e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f2356a25fa8 RCX: 00007f235679e019 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f2356a25fa8 RBP: 00007f2356a25fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2356a26038 R14: 00007fff82f02a10 R15: 00007fff82f02af8 task:udevd state:R running task stack:23480 pid:4979 tgid:4979 ppid:1 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0xa00 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 fb 8c 7e 12 83 f8 07 0f 87 da 00 00 00 48 0f a3 05 86 93 3c 0f 0f 82 ac 02 00 00 8b 35 4e c7 3c 0f 85 f6 0f 85 c7 00 00 00 <48> 8b 44 24 30 65 48 2b 05 9d 8c 7e 12 0f 85 ec 02 00 00 48 83 c4 RSP: 0000:ffffc9000336f868 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e18229c RDI: ffffffff8c402680 RBP: ffffffff8ebe8200 R08: 00000000ffffffff R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2677 [inline] slab_free mm/slub.c:6377 [inline] kmem_cache_free+0x127/0x6b0 mm/slub.c:6504 free_filename fs/namei.c:152 [inline] putname+0xb1/0x110 fs/namei.c:311 class_filename_destructor include/linux/fs.h:2564 [inline] class_filename_maybe_null_destructor include/linux/fs.h:2568 [inline] vfs_fstatat+0x86/0xe0 fs/stat.c:368 __do_sys_newfstatat+0x9d/0x120 fs/stat.c:538 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f674eb11b0a RSP: 002b:00007ffdfc1b3ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 0000563ae0dd1408 RCX: 00007f674eb11b0a RDX: 00007ffdfc1b3cf0 RSI: 0000563ae0dbfef3 RDI: 00000000ffffff9c RBP: 0000563aedb0b668 R08: 00063489548db180 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffdfc1b3cf0 R14: 0000000000000000 R15: 00063489548db180 task:syz-executor state:R running task stack:24168 pid:7782 tgid:7782 ppid:7768 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0xa00 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 fb 8c 7e 12 83 f8 07 0f 87 da 00 00 00 48 0f a3 05 86 93 3c 0f 0f 82 ac 02 00 00 8b 35 4e c7 3c 0f 85 f6 0f 85 c7 00 00 00 <48> 8b 44 24 30 65 48 2b 05 9d 8c 7e 12 0f 85 ec 02 00 00 48 83 c4 RSP: 0018:ffffc90005427bb8 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e18229c RDI: ffffffff8c402680 RBP: ffffffff8ebe8200 R08: 0000000039529a68 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] audit_signal_info_syscall+0x73/0xbb0 kernel/auditsc.c:2688 check_kill_permission+0xb5/0x550 kernel/signal.c:811 group_send_sig_info+0xc2/0x300 kernel/signal.c:1422 kill_pid_info_type+0x92/0x290 kernel/signal.c:1466 kill_pid_info kernel/signal.c:1480 [inline] kill_proc_info+0x6f/0x1b0 kernel/signal.c:1487 kill_something_info+0x2a0/0x310 kernel/signal.c:1584 __do_sys_kill kernel/signal.c:3965 [inline] __se_sys_kill kernel/signal.c:3959 [inline] __x64_sys_kill+0x1c4/0x250 kernel/signal.c:3959 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3e3a73f5a7 RSP: 002b:00007ffda7f16c38 EFLAGS: 00000217 ORIG_RAX: 000000000000003e RAX: ffffffffffffffda RBX: 00000000000001fd RCX: 00007f3e3a73f5a7 RDX: 000000000000012b RSI: 0000000000000009 RDI: 00000000000001fd RBP: 00007ffda7f16c7c R08: 00114b7e2735f886 R09: 0000000000000000 R10: 0000000000011b90 R11: 0000000000000217 R12: 00000000000000e5 R13: 0000000000000064 R14: 0000000000060e70 R15: 00007ffda7f16cd0 rcu: rcu_preempt kthread starved for 9781 jiffies! g90553 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:27432 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: 3224 Comm: kworker/R-bat_e Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:198 Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 b6 cf 27 f6 48 89 df e8 3e 1f 28 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 01 00 00 00 e8 05 2e 17 f6 65 8b 05 4e 57 a6 08 85 c0 74 16 5b RSP: 0018:ffffc90000007c68 EFLAGS: 00000246 RAX: 0000000000000006 RBX: ffff88802ab78000 RCX: 0000000000000004 RDX: 0000000000000000 RSI: ffffffff8e1a815f RDI: ffffffff8c402680 RBP: 0000000000000246 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff8881ac053a10 R13: ffff8881ac053a08 R14: ffff88802b6644a3 R15: ffff88802b664410 FS: 0000000000000000(0000) GS:ffff888123dd8000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6971ad307a CR3: 000000002d1c9000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] dummy_timer+0x1d91/0x36f0 drivers/usb/gadget/udc/dummy_hcd.c:2036 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096 hrtimer_run_softirq+0x17d/0x2c0 kernel/time/hrtimer.c:2113 handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622 do_softirq kernel/softirq.c:523 [inline] do_softirq+0xac/0xe0 kernel/softirq.c:510 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_tt_local_purge+0x21c/0x3d0 net/batman-adv/translation-table.c:1366 batadv_tt_purge+0x8b/0xbd0 net/batman-adv/translation-table.c:3565 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] rescuer_thread+0x905/0x14a0 kernel/workqueue.c:3629 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245