sched: DL replenish lagged too much rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5820/1:b..l P9811/1:b..l P5812/1:b..l rcu: (detected by 0, t=10502 jiffies, g=26969, q=762709 ncpus=2) task:udevd state:R running task stack:24728 pid:5812 tgid:5812 ppid:5185 task_flags:0x400140 flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6929 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7113 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0x61/0x80 kernel/locking/spinlock.c:194 sock_def_readable+0x15b/0x600 net/core/sock.c:3551 unix_dgram_sendmsg+0xd1b/0x17f0 net/unix/af_unix.c:2309 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] sock_write_iter+0x566/0x610 net/socket.c:1195 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x7d3/0x11d0 fs/read_write.c:686 ksys_write+0x1f8/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f44122a7407 RSP: 002b:00007ffdd6773f10 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f44129e4880 RCX: 00007f44122a7407 RDX: 0000000000000000 RSI: 00007ffdd6773fb7 RDI: 000000000000000a RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007f44129e46e8 R13: 0000000000000000 R14: 0000000000000000 R15: 000055b23df7cd50 task:syz.2.1307 state:R running task stack:27752 pid:9811 tgid:9811 ppid:5809 task_flags:0x400040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6929 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7113 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] wp_page_copy mm/memory.c:3781 [inline] do_wp_page+0x186d/0x52b0 mm/memory.c:4141 handle_pte_fault mm/memory.c:6211 [inline] __handle_mm_fault+0x1ae3/0x2aa0 mm/memory.c:6336 handle_mm_fault+0x589/0xd10 mm/memory.c:6505 do_user_addr_fault+0x60c/0x1370 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x64/0xc0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0033:0x7fdbe2a4d75c RSP: 002b:00007ffd84701518 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 00007fdbe3915720 RCX: 0000000000000000 RDX: 0000000000001846 RSI: ffffffff8236b846 RDI: 0000000000000000 RBP: ffffffff8236b846 R08: 00007fdbe2dd0000 R09: 00007fdbe2dd2000 R10: 000000008236b84a R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff8236b40a R15: 0000000000000007 task:udevd state:R running task stack:23768 pid:5820 tgid:5820 ppid:5185 task_flags:0x400140 flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6929 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7256 irqentry_exit+0x36/0x90 kernel/entry/common.c:211 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x62/0x350 kernel/locking/lockdep.c:5872 Code: b6 08 12 83 f8 07 0f 87 bc 02 00 00 89 c0 48 0f a3 05 22 44 e9 0e 0f 82 74 02 00 00 8b 35 9a 74 e9 0e 85 f6 0f 85 8d 00 00 00 <48> 8b 44 24 30 65 48 2b 05 39 b6 08 12 0f 85 c7 02 00 00 48 83 c4 RSP: 0018:ffffc90003207940 EFLAGS: 00000206 RAX: 0000000000000046 RBX: ffffffff8e3c4720 RCX: 00000000ef9d33e4 RDX: 0000000000000000 RSI: ffffffff8da05e9c RDI: ffffffff8bf07040 RBP: 0000000000000002 R08: 0ac0d5affe09d4ff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:867 [inline] class_rcu_constructor include/linux/rcupdate.h:1195 [inline] unwind_next_frame+0xd1/0x20a0 arch/x86/kernel/unwind_orc.c:479 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:56 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:559 slab_free_hook mm/slub.c:2504 [inline] slab_free mm/slub.c:6638 [inline] kmem_cache_free+0x15e/0x6c0 mm/slub.c:6748 file_free fs/file_table.c:79 [inline] __fput+0x68d/0xb70 fs/file_table.c:481 fput_close_sync+0x118/0x210 fs/file_table.c:573 __do_sys_close fs/open.c:1589 [inline] __se_sys_close fs/open.c:1574 [inline] __x64_sys_close+0x8b/0x120 fs/open.c:1574 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f44122a7407 RSP: 002b:00007ffdd6772550 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 00007f44129e4880 RCX: 00007f44122a7407 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008 RBP: 000055b23e526f80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 000055b23df6f820 R13: 00007ffdd67731c0 R14: 00007ffdd6772dc0 R15: 00007ffdd67729c0 rcu: rcu_preempt kthread starved for 10476 jiffies! g26969 f0x2 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:28296 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7026 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+0x675/0x7d0 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: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 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: d7 6c 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 e3 84 29 00 fb f4 3c 0a 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffc90000197de8 EFLAGS: 000002c6 RAX: 000000000075ef2d RBX: 0000000000000001 RCX: ffffffff8b60a2a9 RDX: 0000000000000000 RSI: ffffffff8da2b882 RDI: ffffffff8bf07040 RBP: ffffed1003adc490 R08: 0000000000000001 R09: ffffed10170a6655 R10: ffff8880b85332ab R11: 0000000000000001 R12: 0000000000000001 R13: ffff88801d6e2480 R14: ffffffff90820dd0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888124b08000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdbe2dde230 CR3: 000000002cf55000 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:190 [inline] do_idle+0x38d/0x500 kernel/sched/idle.c:330 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x148