rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 ticks this GP) idle=bd44/1/0x4000000000000000 softirq=260284/260284 fqs=3
rcu: hardirqs softirqs csw/system
rcu: number: 0 0 0
rcu: cputime: 0 0 0 ==> 41530(ms)
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P14325/1:b.el
rcu: (detected by 1, t=10502 jiffies, g=208469, q=1986 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7958 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: krds_cp_wq#10/1 rds_connect_worker
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:649 [inline]
RIP: 0010:cpu_online include/linux/cpumask.h:1231 [inline]
RIP: 0010:trace_hrtimer_start+0x3d/0x200 include/trace/events/timer.h:223
Code: 10 13 00 0f 1f 44 00 00 e8 d0 10 13 00 65 8b 1d dd 5a 87 11 bf 07 00 00 00 89 de e8 fd 14 13 00 83 fb 07 77 61 e8 b3 10 13 00 <41> 89 de c1 eb 06 48 8d 3c dd f0 16 31 90 be 08 00 00 00 e8 ab 67
RSP: 0018:ffffc90000007d68 EFLAGS: 00000006
RAX: ffffffff81b2e56d RBX: 0000000000000000 RCX: ffff8880798b0000
RDX: 0000000000010000 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 0000000000000000 R08: ffffffff9a6a46a3 R09: 1ffffffff34d48d4
R10: dffffc0000000000 R11: fffffbfff34d48d5 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888063ae4300 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88812527c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564518dfe000 CR3: 000000000e746000 CR4: 00000000003526f0
Call Trace:
debug_activate kernel/time/hrtimer.c:529 [inline]
enqueue_hrtimer+0xb7/0x2c0 kernel/time/hrtimer.c:1109
__run_hrtimer kernel/time/hrtimer.c:2048 [inline]
__hrtimer_run_queues+0x4ce/0xa10 kernel/time/hrtimer.c:2096
hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215
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:memcpy_orig+0x8f/0x140 arch/x86/lib/memcpy_64.S:121
Code: 8d 76 e0 4c 89 47 f8 4c 89 4f f0 4c 89 57 e8 4c 89 5f e0 48 8d 7f e0 73 d2 83 c2 20 48 29 d6 48 29 d7 83 fa 10 72 34 4c 8b 06 <4c> 8b 4e 08 4c 8b 54 16 f0 4c 8b 5c 16 f8 4c 89 07 4c 89 4f 08 4c
RSP: 0018:ffffc90004c477f8 EFLAGS: 00000206
RAX: ffffc90004c47840 RBX: 1ffff92000988f04 RCX: ffffffff89702150
RDX: 000000000000001c RSI: ffffc90004c47a00 RDI: ffffc90004c47840
RBP: ffffc90004c47930 R08: 0000000061b1000a R09: 1ffff92000988f0b
R10: dffffc0000000000 R11: fffff52000988f0c R12: ffffc90004c47840
R13: 000000000000001c R14: ffff8880a8501740 R15: dffffc0000000000
kernel_bind+0xf0/0x1c0 net/socket.c:3644
rds_tcp_conn_path_connect+0x53b/0x920 net/rds/tcp_connect.c:175
rds_connect_worker+0x1d8/0x290 net/rds/threads.c:176
process_one_work kernel/workqueue.c:3314 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3478
kthread+0x388/0x470 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
task:dhcpcd state:R running task stack:27000 pid:14325 tgid:14325 ppid:5282 task_flags:0x400140 flags:0x00080001
Call Trace:
context_switch kernel/sched/core.c:5504 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7228
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7409
preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12
__raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline]
_raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:190
spin_unlock include/linux/spinlock.h:390 [inline]
wp_page_copy mm/memory.c:3976 [inline]
do_wp_page+0x3ec0/0x4c70 mm/memory.c:4336
handle_pte_fault mm/memory.c:6443 [inline]
__handle_mm_fault mm/memory.c:6565 [inline]
handle_mm_fault+0x1490/0x3080 mm/memory.c:6734
do_user_addr_fault+0xa4d/0x1340 arch/x86/mm/fault.c:1339
handle_page_fault arch/x86/mm/fault.c:1479 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x5644f54f0370
RSP: 002b:00007ffc15f87c60 EFLAGS: 00010246
RAX: 0000000000000002 RBX: 0000564518dfdfc0 RCX: 0000000000000000
RDX: 0000564518e03f30 RSI: 0000564518e03f50 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000564518e03f60 R09: 0000000000000002
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffc15f87ce0
R13: 0000564518deb8a0 R14: 00007ffc15f87f20 R15: 00007ffc15f87cd0
rcu: rcu_preempt kthread starved for 4153 jiffies! g208469 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:27992 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5504 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7228
__schedule_loop kernel/sched/core.c:7307 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7322
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
kthread+0x388/0x470 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: 28094 Comm: kworker/u8:47 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x10c2/0x14b0 kernel/smp.c:892
Code: 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 44 fe 0b 00 eb 37 f3 90 41 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e 29 fe 0b 00 eb e5 44 89 f1 80 e1 07 80 c1 03 38 c1 7c e3 4c 89
RSP: 0018:ffffc90003eb6260 EFLAGS: 00000202
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff88802c833e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003eb6390 R08: ffff88809cb8cbc7 R09: 1ffff11013971978
R10: dffffc0000000000 R11: ffffed1013971979 R12: 1ffff110170c85c5
R13: ffff8880b873c2c8 R14: ffff8880b8642e28 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88812537c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fce6f528790 CR3: 0000000024ecc000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
__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+0x5c4/0x1090 arch/x86/mm/tlb.c:1451
flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline]
ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:104
page_vma_mkclean_one+0x43f/0x780 mm/rmap.c:1138
page_mkclean_one+0x1d8/0x2b0 mm/rmap.c:1186
__rmap_walk_file+0x450/0x610 mm/rmap.c:3064
rmap_walk mm/rmap.c:3108 [inline]
folio_mkclean+0x2d5/0x3f0 mm/rmap.c:1218
folio_clear_dirty_for_io+0x190/0x820 mm/page-writeback.c:2909
mpage_submit_folio+0x83/0x2a0 fs/ext4/inode.c:2084
mpage_process_page_bufs+0x6b2/0x8c0 fs/ext4/inode.c:2214
mpage_prepare_extent_to_map+0xe0e/0x1690 fs/ext4/inode.c:2753
ext4_do_writepages+0xc36/0x47a0 fs/ext4/inode.c:2894
ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3042
do_writepages+0x338/0x560 mm/page-writeback.c:2571
__writeback_single_inode+0x12e/0xf90 fs/fs-writeback.c:1787
writeback_sb_inodes+0x9de/0x1b00 fs/fs-writeback.c:2079
__writeback_inodes_wb+0x114/0x240 fs/fs-writeback.c:2155
wb_writeback+0x42f/0xad0 fs/fs-writeback.c:2266
wb_check_old_data_flush fs/fs-writeback.c:2370 [inline]
wb_do_writeback fs/fs-writeback.c:2449 [inline]
wb_workfn+0xc92/0x10f0 fs/fs-writeback.c:2477
process_one_work kernel/workqueue.c:3314 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3478
kthread+0x388/0x470 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