rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (3 ticks this GP) idle=e77c/1/0x4000000000000000 softirq=120469/120481 fqs=3 rcu: (detected by 0, t=10506 jiffies, g=136377, q=265 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 23034 Comm: syz.1.4523 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x83/0x90 kernel/kcov.c:302 Code: 8d 52 28 4d 39 ca 77 22 89 ff 89 f6 49 ff c0 4c 89 01 48 c7 44 11 08 01 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 cc cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000a08d38 EFLAGS: 00000006 RAX: ffffffff81ae90a4 RBX: ffff8880b87283c8 RCX: 0000000000010000 RDX: ffff8880115a3c80 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90000a08e90 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: ffff888033a52300 R13: dffffc0000000000 R14: ffff8880b8728280 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888125cf9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f225c9d5d58 CR3: 000000000df3e000 CR4: 00000000003526f0 Call Trace: __remove_hrtimer kernel/time/hrtimer.c:1119 [inline] __run_hrtimer kernel/time/hrtimer.c:1765 [inline] __hrtimer_run_queues+0x344/0xc30 kernel/time/hrtimer.c:1849 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1911 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x3e0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194 Code: f7 e8 8d cb 3d f6 f7 c3 00 02 00 00 74 05 e8 30 a9 67 f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 d4 d6 2f f6 65 8b 05 1d 39 41 07 85 c0 74 18 5b 41 5e e9 01 47 RSP: 0018:ffffc9000452f068 EFLAGS: 00000206 RAX: 0000000000000006 RBX: 0000000000000286 RCX: 0000000080000001 RDX: 0000000000000000 RSI: ffffffff8d9a73db RDI: 0000000000000001 RBP: 0000000000000000 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: ffff88804ef9a000 R13: ffff88804ef99000 R14: ffffffff99d3cf88 R15: 0000000000000001 __debug_check_no_obj_freed lib/debugobjects.c:1108 [inline] debug_check_no_obj_freed+0x52e/0x550 lib/debugobjects.c:1129 free_pages_prepare mm/page_alloc.c:1443 [inline] free_unref_folios+0x4cb/0x13e0 mm/page_alloc.c:3033 folios_put_refs+0x584/0x670 mm/swap.c:1002 folio_batch_release include/linux/pagevec.h:101 [inline] shmem_undo_range+0x49e/0x1490 mm/shmem.c:1138 shmem_truncate_range mm/shmem.c:1250 [inline] shmem_evict_inode+0x26e/0xa70 mm/shmem.c:1380 evict+0x5f4/0xae0 fs/inode.c:837 __dentry_kill+0x209/0x660 fs/dcache.c:670 finish_dput+0xc9/0x480 fs/dcache.c:879 __fput+0x68e/0xa70 fs/file_table.c:476 task_work_run+0x1d4/0x260 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x694/0x22f0 kernel/exit.c:971 do_group_exit+0x21c/0x2d0 kernel/exit.c:1112 get_signal+0x1285/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x87/0x4e0 kernel/entry/common.c:75 __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_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f225e78f749 Code: Unable to access opcode bytes at 0x7f225e78f71f. RSP: 002b:00007f225c9d50e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f225e9e6098 RCX: 00007f225e78f749 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f225e9e6098 RBP: 00007f225e9e6090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f225e9e6128 R14: 00007ffc209ac110 R15: 00007ffc209ac1f8 rcu: rcu_preempt kthread starved for 10490 jiffies! g136377 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:27392 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5290 [inline] __schedule+0x14db/0x5030 kernel/sched/core.c:6902 __schedule_loop kernel/sched/core.c:6984 [inline] schedule+0x165/0x360 kernel/sched/core.c:6999 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297 kthread+0x389/0x480 kernel/kthread.c:467 ret_from_fork+0x510/0xa50 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: 23033 Comm: syz.8.4525 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xcdd/0x1260 kernel/smp.c:877 Code: 00 00 00 00 fc ff df 75 07 e8 5f 96 0b 00 eb 38 f3 90 42 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 43 96 0b 00 e4 44 89 e1 80 e1 07 80 c1 03 38 c1 7c e2 4c 89 e7 e8 2c 6b 72 RSP: 0018:ffffc9000460f4a0 EFLAGS: 00000293 RAX: ffffffff81b5835d RBX: 1ffff110170e8179 RCX: ffff888056d1dac0 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000460f5e0 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: ffff8880b8740bc8 R13: dffffc0000000000 R14: ffff8880b863bd80 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888125bf9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c33a6b2 CR3: 000000000df3e000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:57 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x5db/0x1100 arch/x86/mm/tlb.c:1472 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:505 [inline] tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:529 free_ldt_pgtables+0x17b/0x320 arch/x86/kernel/ldt.c:411 arch_exit_mmap arch/x86/include/asm/mmu_context.h:234 [inline] exit_mmap+0x141/0xae0 mm/mmap.c:1263 __mmput+0x118/0x430 kernel/fork.c:1173 exit_mm+0x169/0x230 kernel/exit.c:581 do_exit+0x627/0x22f0 kernel/exit.c:959 do_group_exit+0x21c/0x2d0 kernel/exit.c:1112 get_signal+0x1285/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x87/0x4e0 kernel/entry/common.c:75 __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_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7efe6518f749 Code: Unable to access opcode bytes at 0x7efe6518f71f. RSP: 002b:00007efe65f49038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: fffffffffffffe00 RBX: 00007efe653e6090 RCX: 00007efe6518f749 RDX: 0000000000002020 RSI: 0000200000000980 RDI: 0000000000000004 RBP: 00007efe65213f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007efe653e6128 R14: 00007efe653e6090 R15: 00007ffc52378018