rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10503 jiffies, g=83973, q=962 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4295091492-4295080991), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10501 jiffies! g83973 f0x2 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:27304 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x165/0x360 kernel/sched/core.c:6860 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2046 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2248 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4e/0x80 arch/x86/kernel/process.c:153 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 20907 Comm: syz.2.3649 Not tainted 6.15.0-rc4-syzkaller-00147-gebd297a2affa #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:227 [inline] RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:239 [inline] RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline] RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:587 [inline] RIP: 0010:cpu_online include/linux/cpumask.h:1143 [inline] RIP: 0010:trace_hrtimer_start include/trace/events/timer.h:222 [inline] RIP: 0010:debug_activate kernel/time/hrtimer.c:485 [inline] RIP: 0010:enqueue_hrtimer+0x81/0x3a0 kernel/time/hrtimer.c:1088 Code: 00 00 e8 f2 68 11 00 45 89 fd 41 c1 ef 06 4a 8d 3c fd 70 d3 7e 8f be 08 00 00 00 e8 49 60 73 00 31 f6 4c 0f a3 2d ef 7b d0 0d <40> 0f 92 c5 40 0f 92 c6 bf 02 00 00 00 e8 bd 6b 11 00 40 84 ed 74 RSP: 0018:ffffc90000007d08 EFLAGS: 00000047 RAX: ffffffff81ae5701 RBX: ffff8880114a5340 RCX: ffffffff81ae5777 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8f7ed370 RBP: 0000000000000000 R08: ffffffff8f7ed377 R09: 1ffffffff1efda6e R10: dffffc0000000000 R11: fffffbfff1efda6f R12: dffffc0000000000 R13: 0000000000000000 R14: ffff8880b88277c0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881260cc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8fce3b7bac CR3: 00000000536fa000 CR4: 0000000000350ef0 Call Trace: __run_hrtimer kernel/time/hrtimer.c:1778 [inline] __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:206 [inline] RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:238 [inline] RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline] RIP: 0010:folio_test_head include/linux/page-flags.h:860 [inline] RIP: 0010:folio_test_large include/linux/page-flags.h:881 [inline] RIP: 0010:folio_mapcount include/linux/mm.h:1363 [inline] RIP: 0010:zap_present_folio_ptes mm/memory.c:1527 [inline] RIP: 0010:zap_present_ptes mm/memory.c:1586 [inline] RIP: 0010:do_zap_pte_range mm/memory.c:1687 [inline] RIP: 0010:zap_pte_range mm/memory.c:1731 [inline] RIP: 0010:zap_pmd_range mm/memory.c:1823 [inline] RIP: 0010:zap_pud_range mm/memory.c:1852 [inline] RIP: 0010:zap_p4d_range mm/memory.c:1873 [inline] RIP: 0010:unmap_page_range+0x1842/0x4210 mm/memory.c:1894 Code: 48 83 e6 01 31 ff e8 fd 0c b7 ff 48 83 e3 01 0f 85 02 28 00 00 4c 89 e7 be 08 00 00 00 e8 76 ff 18 00 48 8b 84 24 20 01 00 00 <48> b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 e7 e8 e6 fc RSP: 0018:ffffc9000468f420 EFLAGS: 00000256 RAX: 1ffffd4000319268 RBX: 0000000000000000 RCX: ffffffff8208b84a RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffea00018c9340 RBP: ffffc9000468f6b0 R08: ffffea00018c9347 R09: 1ffffd4000319268 R10: dffffc0000000000 R11: fffff94000319269 R12: ffffea00018c9340 R13: dffffc0000000000 R14: ffff8880593d2228 R15: 00007fdbcc445000 unmap_vmas+0x25d/0x3c0 mm/memory.c:1984 exit_mmap+0x245/0xba0 mm/mmap.c:1284 __mmput+0x118/0x420 kernel/fork.c:1379 exit_mm+0x1da/0x2c0 kernel/exit.c:589 do_exit+0x859/0x2550 kernel/exit.c:940 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102 get_signal+0x125e/0x1310 kernel/signal.c:3034 arch_do_signal_or_restart+0x95/0x780 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x8b/0x120 kernel/entry/common.c:218 do_syscall_64+0x103/0x210 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdbcd58e969 Code: Unable to access opcode bytes at 0x7fdbcd58e93f. RSP: 002b:00007fdbce41e0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007fdbcd7b5fa8 RCX: 00007fdbcd58e969 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007fdbcd7b5fac RBP: 00007fdbcd7b5fa0 R08: 7fffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdbcd7b5fac R13: 0000000000000000 R14: 00007ffd2d9afd60 R15: 00007ffd2d9afe48