rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5151/2:b..l P13718/3:b..l rcu: (detected by 0, t=10502 jiffies, g=54725, q=1141 ncpus=2) task:syz.5.2552 state:R running task stack:26880 pid:13718 tgid:13677 ppid:8696 task_flags:0x40044c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x1553/0x5240 kernel/sched/core.c:6911 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7238 irqentry_exit+0x599/0x620 kernel/entry/common.c:239 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x20b/0x2e0 kernel/locking/lockdep.c:5872 Code: e9 30 ff ff ff e8 35 0e 84 09 f7 c3 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 a1 ab ae 10 48 3b 44 24 30 75 33 fb 48 83 c4 38 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 06 ce 87 09 cc 48 8d 3d be 65 cd RSP: 0018:ffffc90004b7f310 EFLAGS: 00000292 RAX: 6ca8ac4e9fdc7f00 RBX: 0000000000000246 RCX: 0000000000000046 RDX: 00000000c8b490ac RSI: ffffffff8d7c20bd RDI: ffffffff8ba67a80 RBP: 0000000000000000 R08: ffffffff823204e4 R09: ffffffff8ddcb980 R10: dffffc0000000000 R11: fffff940003acfa9 R12: 0000000000000002 R13: ffffffff8ddcb980 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:312 [inline] rcu_read_lock include/linux/rcupdate.h:850 [inline] page_table_check_clear+0x164/0x5f0 mm/page_table_check.c:77 ptep_get_and_clear_full arch/x86/include/asm/jump_label.h:-1 [inline] get_and_clear_full_ptes include/linux/pgtable.h:846 [inline] zap_present_folio_ptes mm/memory.c:1643 [inline] zap_present_ptes mm/memory.c:1725 [inline] do_zap_pte_range mm/memory.c:1827 [inline] zap_pte_range mm/memory.c:1929 [inline] zap_pmd_range mm/memory.c:2021 [inline] zap_pud_range mm/memory.c:2049 [inline] zap_p4d_range mm/memory.c:2070 [inline] unmap_page_range+0x3015/0x4540 mm/memory.c:2091 unmap_single_vma mm/memory.c:2133 [inline] unmap_vmas+0x48f/0x6a0 mm/memory.c:2171 exit_mmap+0x280/0xa10 mm/mmap.c:1302 __mmput+0xcb/0x3d0 kernel/fork.c:1175 exit_mm+0x168/0x220 kernel/exit.c:581 do_exit+0x6a2/0x23c0 kernel/exit.c:964 do_group_exit+0x21b/0x2d0 kernel/exit.c:1118 get_signal+0x125c/0x1310 kernel/signal.c:3034 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f618d2cc4ab RSP: 002b:00007f618b4e1f50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00007f618d2cc4ab RDX: 00007f618b4e2fe0 RSI: 0000000080085502 RDI: 0000000000000003 RBP: 00007f618d362c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f618d546180 R15: 00007ffd85671208 task:klogd state:R running task stack:23520 pid:5151 tgid:5151 ppid:1 task_flags:0x400100 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x1553/0x5240 kernel/sched/core.c:6911 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7095 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 class_preempt_destructor include/linux/preempt.h:468 [inline] try_to_wake_up+0x832/0x1380 kernel/sched/core.c:4249 autoremove_wake_function+0x17/0x100 kernel/sched/wait.c:403 __wake_up_common kernel/sched/wait.c:108 [inline] __wake_up_common_lock+0x136/0x1e0 kernel/sched/wait.c:125 sock_def_readable+0x1ee/0x580 net/core/sock.c:3611 unix_dgram_sendmsg+0xe1c/0x18e0 net/unix/af_unix.c:2283 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] __sys_sendto+0x67f/0x710 net/socket.c:2206 __do_sys_sendto net/socket.c:2213 [inline] __se_sys_sendto net/socket.c:2209 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2209 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f994aff0407 RSP: 002b:00007ffe52684330 EFLAGS: 00000202 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f994aea0c80 RCX: 00007f994aff0407 RDX: 000000000000005f RSI: 00007ffe52684470 RDI: 0000000000000003 RBP: 00007ffe526848a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000004000 R11: 0000000000000202 R12: 00007ffe526848b8 R13: 00007ffe52684470 R14: 0000000000000044 R15: 00007ffe52684470 rcu: rcu_preempt kthread starved for 1876 jiffies! g54725 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:27016 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x1553/0x5240 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0x164/0x360 kernel/sched/core.c:7008 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 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: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63 Code: 4e 5c 02 e9 13 c4 03 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d f3 2c 25 00 fb f4 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0000:ffffc900001d7e20 EFLAGS: 00000246 RAX: 0000000000f51b5f RBX: ffffffff81996bfa RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8d565fee RDI: ffffffff8ba67a80 RBP: ffffc900001d7f10 R08: ffff8880b8933e1b R09: 1ffff110171267c3 R10: dffffc0000000000 R11: ffffed10171267c4 R12: 0000000000000001 R13: 1ffff110039d0000 R14: 0000000000000001 R15: 1ffff110039d0000 FS: 0000000000000000(0000) GS:ffff888126432000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f2ae1a6cb10 CR3: 000000005a6c0000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/kernel/process.c:766 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x36a/0x5f0 kernel/sched/idle.c:352 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x147