rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=4c74/1/0x4000000000000000 softirq=118833/118834 fqs=4 rcu: (detected by 1, t=10505 jiffies, g=131625, q=543 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 15324 Comm: cmp Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2026 RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:650 [inline] RIP: 0010:cpu_online include/linux/cpumask.h:1232 [inline] RIP: 0010:trace_hrtimer_expire_entry include/trace/events/timer.h:261 [inline] RIP: 0010:__run_hrtimer kernel/time/hrtimer.c:2071 [inline] RIP: 0010:__hrtimer_run_queues+0x2ed/0xa10 kernel/time/hrtimer.c:2131 Code: 00 e8 c7 9d 13 00 65 8b 1d f8 11 e1 11 bf 07 00 00 00 89 de e8 b4 a2 13 00 83 fb 07 0f 87 74 02 00 00 e8 a6 9d 13 00 41 89 dc eb 06 48 8d 3c dd 78 51 7a 90 be 08 00 00 00 e8 3e a9 83 00 31 RSP: 0018:ffffc90000007dc0 EFLAGS: 00000002 RAX: ffffffff81b43e5a RBX: 0000000000000000 RCX: ffff888036091f40 RDX: 8000000001000001 RSI: 0000000001000001 RDI: 0000000000000007 RBP: ffff888068089300 R08: 0000000001000001 R09: 1ffff110170c5050 R10: dffffc0000000000 R11: ffffed10170c5051 R12: 0000000000000000 R13: ffffffff89edf340 R14: ffff8880b8628520 R15: 1ffff110170c509a FS: 0000000000000000(0000) GS:ffff888124ccb000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe2d1387000 CR3: 000000005676d000 CR4: 0000000000350ef0 Call Trace: hrtimer_interrupt+0x4cd/0xaa0 kernel/time/hrtimer.c:2250 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:81 [inline] RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:103 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:238 [inline] RIP: 0010:unwind_next_frame+0x4df/0x2550 arch/x86/kernel/unwind_orc.c:510 Code: 16 00 00 e9 ee 01 00 00 49 89 d5 49 89 d7 4c 89 e0 4c 29 f8 48 89 c1 48 c1 f9 02 48 c1 e8 3f 48 01 c8 48 83 e0 fe 49 8d 1c 47 <48> 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 RSP: 0018:ffffc90003d4ee60 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffffff909e90e4 RCX: 0000000000000000 RDX: ffffffff909e90e4 RSI: ffffffff9122d100 RDI: ffffffff8c6da720 RBP: ffffffff82541ee7 R08: 0000000000000001 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffffff81b293f0 R12: ffffffff909e90e4 R13: ffffffff909e90e4 R14: ffffc90003d4ef08 R15: ffffffff909e90e4 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 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:6508 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6635 jbd2_free_handle include/linux/jbd2.h:1617 [inline] jbd2_journal_stop+0x917/0xdd0 fs/jbd2/transaction.c:2022 __ext4_journal_stop+0xf2/0x330 fs/ext4/ext4_jbd2.c:144 __mark_inode_dirty+0x3a8/0x13b0 fs/fs-writeback.c:2729 generic_update_time fs/inode.c:2253 [inline] touch_atime+0x568/0x670 fs/inode.c:2328 file_accessed include/linux/fs.h:2277 [inline] ext4_file_mmap_prepare+0x277/0x450 fs/ext4/file.c:901 vfs_mmap_prepare include/linux/fs.h:2069 [inline] call_mmap_prepare mm/vma.c:2784 [inline] __mmap_region mm/vma.c:2873 [inline] mmap_region+0xe7e/0x2270 mm/vma.c:2974 do_mmap+0xe0a/0x1300 mm/mmap.c:573 vm_mmap_pgoff+0x272/0x4e0 mm/util.c:581 ksys_mmap_pgoff+0x4dc/0x760 mm/mmap.c:619 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: 0033:0x7f8974b46242 Code: 08 00 04 00 00 eb e2 90 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 33 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 5e 5b 5d c3 0f 1f 00 c7 05 46 40 01 00 16 00 RSP: 002b:00007ffefe9bbf28 EFLAGS: 00000206 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f89747b4000 RCX: 00007f8974b46242 RDX: 0000000000000005 RSI: 0000000000037000 RDI: 00007f89747b4000 RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000003000 R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffefe9bbf78 R13: 00007f897481d6b0 R14: 00007ffefe9bc360 R15: 00000fffdfd377e8 rcu: rcu_preempt kthread starved for 10485 jiffies! g131625 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:28112 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7284 __schedule_loop kernel/sched/core.c:7361 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7376 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: 1 UID: 0 PID: 15310 Comm: syz.0.1504 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2026 RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x80 kernel/kcov.c:212 Code: 8b 3d 64 a4 a6 0c 48 89 de 5b e9 23 87 64 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d f8 73 cd 11 65 48 8b 15 f8 73 cd 11 f7 c2 00 01 00 ff RSP: 0018:ffffc90000a0f058 EFLAGS: 00000202 RAX: ffffffff81bb8afe RBX: ffff8880b8643708 RCX: ffff888052fb0000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90000a0f1b0 R08: ffff888052fb159f R09: 1ffff1100a5f62b3 R10: dffffc0000000000 R11: ffffffff8179dc60 R12: 1ffff110170c86e1 R13: 0000000000000000 R14: ffff8880b8643700 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888124dcb000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe2d1056e9c CR3: 0000000058130000 CR4: 0000000000350ef0 Call Trace: csd_lock_wait kernel/smp.c:363 [inline] csd_lock kernel/smp.c:396 [inline] smp_call_function_many_cond+0x63e/0x1500 kernel/smp.c:944 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x8ff/0x1090 arch/x86/mm/tlb.c:1435 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:509 [inline] zap_pte_range mm/memory.c:2092 [inline] zap_pmd_range mm/memory.c:2151 [inline] zap_pud_range mm/memory.c:2179 [inline] zap_p4d_range mm/memory.c:2200 [inline] __zap_vma_range+0x3f52/0x4f80 mm/memory.c:2240 unmap_vmas+0x390/0x550 mm/memory.c:2309 exit_mmap+0x293/0x9f0 mm/mmap.c:1315 __mmput+0x118/0x420 kernel/fork.c:1193 exit_mm+0x221/0x2d0 kernel/exit.c:618 do_exit+0x6cd/0x2360 kernel/exit.c:1000 do_group_exit+0x22d/0x2f0 kernel/exit.c:1155 get_signal+0x121b/0x12c0 kernel/signal.c:3112 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x10e/0x770 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:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2de4d9e159 Code: Unable to access opcode bytes at 0x7f2de4d9e12f. RSP: 002b:00007f2de5c090e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f2de5025fa8 RCX: 00007f2de4d9e159 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f2de5025fa8 RBP: 00007f2de5025fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2de5026038 R14: 00007fff74c0f960 R15: 00007fff74c0fa48