rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6608/1:b..l rcu: (detected by 0, t=10503 jiffies, g=13489, q=1401 ncpus=2) task:udevd state:R running task stack:26408 pid:6608 tgid:6608 ppid:5187 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:60 [inline] RIP: 0010:stack_access_ok+0x8e/0x200 arch/x86/kernel/unwind_orc.c:409 Code: 00 00 00 fc ff df 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e 0b 01 00 00 8b 13 85 d2 74 23 49 39 ef 77 1e 48 39 e9 76 19 <4a> 8d 54 25 00 49 39 d7 0f 92 c0 48 39 d1 0f 93 c2 20 d0 0f 85 ba RSP: 0018:ffffc9000fab78c8 EFLAGS: 00000202 RAX: 0000000000000000 RBX: ffffc9000fab7978 RCX: ffffc9000fab8000 RDX: 0000000000000001 RSI: ffffc9000fab7d90 RDI: ffffc9000fab7978 RBP: ffffc9000fab7d90 R08: ffffffff91352f9c R09: 00000000ffffffff R10: 0000000000000002 R11: 0000000000016b3a R12: 0000000000000008 R13: ffffc9000fab7988 R14: ffffc9000fab7980 R15: ffffc9000fab0000 deref_stack_reg arch/x86/kernel/unwind_orc.c:419 [inline] unwind_next_frame+0xb7d/0x20b0 arch/x86/kernel/unwind_orc.c:600 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] kernfs_iop_get_link fs/kernfs/symlink.c:137 [inline] kernfs_iop_get_link+0x65/0x1670 fs/kernfs/symlink.c:128 vfs_readlink+0x213/0x440 fs/namei.c:6140 do_readlinkat+0x24a/0x3a0 fs/stat.c:590 __do_sys_readlink fs/stat.c:613 [inline] __se_sys_readlink fs/stat.c:610 [inline] __x64_sys_readlink+0x78/0xc0 fs/stat.c:610 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe19f6483a7 RSP: 002b:00007ffce27d6b88 EFLAGS: 00000202 ORIG_RAX: 0000000000000059 RAX: ffffffffffffffda RBX: 00007ffce27d73d0 RCX: 00007fe19f6483a7 RDX: 0000000000000400 RSI: 00007ffce27d6f90 RDI: 00007ffce27d6b90 RBP: 0000000000000200 R08: 0000560fbf2cec29 R09: 0000000000000000 R10: 0000000000000010 R11: 0000000000000202 R12: 00007ffce27d6b90 R13: 00007ffce27d6f90 R14: 00007ffce27d7ce0 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10526 jiffies! g13489 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:28440 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 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:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: c6 5f 02 c3 cc cc cc cc 0f 1f 00 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 13 49 12 00 fb f4 cc 35 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0000:ffffffff8e007df8 EFLAGS: 000002c6 RAX: 00000000011f0def RBX: 0000000000000000 RCX: ffffffff8b7816d9 RDX: 0000000000000000 RSI: ffffffff8dace4f3 RDI: ffffffff8bf2b480 RBP: fffffbfff1c12f68 R08: 0000000000000001 R09: ffffed101708673d R10: ffff8880b84339eb R11: ffffffff8e098670 R12: 0000000000000000 R13: ffffffff8e097b40 R14: ffffffff9088b9d0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881248f5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b301f8ff8 CR3: 00000000317f6000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x38d/0x510 kernel/sched/idle.c:332 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430 rest_init+0x16b/0x2b0 init/main.c:757 start_kernel+0x3ef/0x4d0 init/main.c:1206 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x148