rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=b53c/1/0x4000000000000000 softirq=72663/72664 fqs=0 rcu: (detected by 1, t=10506 jiffies, g=57209, q=268 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5815 Comm: syz-executor Not tainted 6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 RIP: 0010:__sanitizer_cov_trace_cmp8+0x0/0x20 kernel/kcov.c:293 Code: 0c 24 89 f2 89 fe bf 04 00 00 00 e9 ea fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 8b 0c 24 48 89 f2 48 89 fe bf 06 00 00 00 e9 b8 fe RSP: 0018:ffffc90000007dd8 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: ffff888079118340 RCX: ffffffff81a858b4 RDX: 1ffff1100f223068 RSI: ffff888079118340 RDI: 0000000000000001 RBP: ffff8880b8427990 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000000 R14: ffff8880b8427840 R15: 0000000000000000 FS: 000055556b106500(0000) GS:ffff8881249e2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3189bb7bac CR3: 000000005e84b000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: timerqueue_del+0x40/0x150 lib/timerqueue.c:55 __remove_hrtimer+0x99/0x290 kernel/time/hrtimer.c:1121 __run_hrtimer kernel/time/hrtimer.c:1741 [inline] __hrtimer_run_queues+0x4f9/0xad0 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__sanitizer_cov_trace_pc+0x66/0x70 kernel/kcov.c:235 Code: 82 18 16 00 00 83 f8 02 75 20 48 8b 8a 20 16 00 00 8b 92 1c 16 00 00 48 8b 01 48 83 c0 01 48 39 d0 73 07 48 89 01 48 89 34 c1 cc cc cc cc 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90003e9f670 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 000000000006cb29 RCX: ffffffff822c3069 RDX: ffff888026398000 RSI: ffffffff822c30cc RDI: 0000000000000007 RBP: ffff88813fffa5a0 R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000008 R11: 0000000000000000 R12: 0000000000000008 R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000000 rcu_read_unlock_sched include/linux/rcupdate.h:951 [inline] pfn_valid include/linux/mmzone.h:2127 [inline] page_table_check_set+0x1fc/0xb50 mm/page_table_check.c:105 __page_table_check_ptes_set+0x318/0x420 mm/page_table_check.c:209 page_table_check_ptes_set include/linux/page_table_check.h:74 [inline] set_ptes include/linux/pgtable.h:292 [inline] __copy_present_ptes mm/memory.c:961 [inline] copy_present_ptes mm/memory.c:1044 [inline] copy_pte_range mm/memory.c:1167 [inline] copy_pmd_range mm/memory.c:1255 [inline] copy_pud_range mm/memory.c:1292 [inline] copy_p4d_range mm/memory.c:1316 [inline] copy_page_range+0x1bd2/0x5fe0 mm/memory.c:1410 dup_mmap kernel/fork.c:726 [inline] dup_mm kernel/fork.c:1734 [inline] copy_mm kernel/fork.c:1786 [inline] copy_process+0x862b/0x91a0 kernel/fork.c:2429 kernel_clone+0xfc/0x960 kernel/fork.c:2844 __do_sys_clone+0xce/0x120 kernel/fork.c:2987 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7ba5d851d3 Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00 RSP: 002b:00007fff68f23198 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7ba5d851d3 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 000055556b1067d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 00000000000c0d2f R15: 00007fff68f23330 rcu: rcu_preempt kthread starved for 10506 jiffies! g57209 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:27192 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x116f/0x5de0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6860 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 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: CPU: 1 UID: 0 PID: 15326 Comm: syz.5.2472 Not tainted 6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0x4a5/0x1290 kernel/smp.c:885 Code: 89 ee e8 be 12 0c 00 85 ed 74 48 48 8b 44 24 20 49 89 c4 83 e0 07 49 c1 ec 03 48 89 c5 4d 01 f4 83 c5 03 e8 5d 17 0c 00 f3 90 <41> 0f b6 04 24 40 38 c5 7c 08 84 c0 0f 85 de 0b 00 00 8b 43 08 31 RSP: 0018:ffffc90011807ad8 EFLAGS: 00000246 RAX: 0000000000080000 RBX: ffff8880b8441720 RCX: ffffc9001c489000 RDX: 0000000000080000 RSI: ffffffff81af1b93 RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffed10170882e5 R13: 0000000000000001 R14: dffffc0000000000 R15: ffff8880b853b040 FS: 00007f318a7fc6c0(0000) GS:ffff888124ae2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2fa19ff8 CR3: 0000000012a4b000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1052 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2455 [inline] text_poke_bp_batch+0x220/0x760 arch/x86/kernel/alternative.c:2665 text_poke_flush arch/x86/kernel/alternative.c:2856 [inline] text_poke_flush arch/x86/kernel/alternative.c:2853 [inline] text_poke_finish+0x30/0x40 arch/x86/kernel/alternative.c:2863 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 jump_label_update+0x376/0x550 kernel/jump_label.c:919 static_key_slow_inc_cpuslocked kernel/jump_label.c:168 [inline] static_key_slow_inc_cpuslocked+0x82/0x120 kernel/jump_label.c:151 static_key_slow_inc+0x1a/0x30 kernel/jump_label.c:191 io_uring_create io_uring/io_uring.c:3695 [inline] io_uring_setup+0x187b/0x2090 io_uring/io_uring.c:3834 __do_sys_io_uring_setup io_uring/io_uring.c:3868 [inline] __se_sys_io_uring_setup io_uring/io_uring.c:3859 [inline] __x64_sys_io_uring_setup+0xc2/0x170 io_uring/io_uring.c:3859 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f318998e969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f318a7fbfc8 EFLAGS: 00000202 ORIG_RAX: 00000000000001a9 RAX: ffffffffffffffda RBX: 00007f3189bb5fa0 RCX: 00007f318998e969 RDX: 0000200000000080 RSI: 00002000000003c0 RDI: 00000000000010d2 RBP: 00002000000003c0 R08: 0000000000000000 R09: 0000200000000080 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00002000000000c0 R14: 00000000000010d2 R15: 0000200000000080