rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5610/1:b..l P5608/1:b..l rcu: (detected by 0, t=10506 jiffies, g=42557, q=262 ncpus=2) task:syz-executor state:R running task stack:23880 pid:5608 tgid:5608 ppid:5602 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x10e9/0x6820 kernel/sched/core.c:7188 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7369 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:190 spin_unlock include/linux/spinlock.h:390 [inline] copy_pte_range mm/memory.c:1331 [inline] copy_pmd_range mm/memory.c:1392 [inline] copy_pud_range mm/memory.c:1429 [inline] copy_p4d_range mm/memory.c:1453 [inline] copy_page_range+0x1c02/0x5b00 mm/memory.c:1539 dup_mmap+0xd25/0x2180 mm/mmap.c:1840 dup_mm kernel/fork.c:1534 [inline] copy_mm kernel/fork.c:1586 [inline] copy_process+0x6c63/0x7e00 kernel/fork.c:2264 kernel_clone+0x12e/0x9c0 kernel/fork.c:2721 __do_sys_clone+0xd9/0x120 kernel/fork.c:2862 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9d65fc5852 RSP: 002b:00007fffcb4dcba0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fffcb4dcba0 RCX: 00007f9d65fc5852 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007fffcb4dcd2c R08: 0000000000000000 R09: 0000000000000001 R10: 000055559479a7d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 0000000000094e45 R15: 00007fffcb4dcd80 task:syz-executor state:R running task stack:22632 pid:5610 tgid:5610 ppid:5605 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x10e9/0x6820 kernel/sched/core.c:7188 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7369 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:190 spin_unlock include/linux/spinlock.h:390 [inline] copy_pte_range mm/memory.c:1331 [inline] copy_pmd_range mm/memory.c:1392 [inline] copy_pud_range mm/memory.c:1429 [inline] copy_p4d_range mm/memory.c:1453 [inline] copy_page_range+0x1c02/0x5b00 mm/memory.c:1539 dup_mmap+0xd25/0x2180 mm/mmap.c:1840 dup_mm kernel/fork.c:1534 [inline] copy_mm kernel/fork.c:1586 [inline] copy_process+0x6c63/0x7e00 kernel/fork.c:2264 kernel_clone+0x12e/0x9c0 kernel/fork.c:2721 __do_sys_clone+0xd9/0x120 kernel/fork.c:2862 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc5585c5852 RSP: 002b:00007ffc3f2e5770 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffc3f2e5770 RCX: 00007fc5585c5852 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffc3f2e58fc R08: 0000000000000000 R09: 0000000000000001 R10: 000055557556c7d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 0000000000094e1a R15: 00007ffc3f2e5950 rcu: rcu_preempt kthread starved for 10506 jiffies! g42557 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:28216 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x10e9/0x6820 kernel/sched/core.c:7188 __schedule_loop kernel/sched/core.c:7267 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7282 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: 10526 Comm: syz.2.1002 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x17/0x70 kernel/kcov.c:217 Code: 02 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 65 8b 05 05 16 02 12 48 8b 34 24 65 48 8b 15 e1 15 02 12 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 e9 d1 b0 RSP: 0018:ffffc900039bf260 EFLAGS: 00000202 RAX: 0000000000000003 RBX: 0000000000000001 RCX: ffffffff81fc0dbd RDX: ffff888028eaca00 RSI: ffffffff81fc0d97 RDI: ffff888028eaca00 RBP: ffff8880b8540f40 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003 R13: ffffed10170a81e9 R14: 0000000000000001 R15: ffff8880b843c5c0 FS: 00007f0a5829d6c0(0000) GS:ffff888124376000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000b36030 CR3: 0000000075657000 CR4: 00000000003526f0 Call Trace: native_pause arch/x86/include/asm/vdso/processor.h:13 [inline] cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] csd_lock_wait kernel/smp.c:342 [inline] smp_call_function_many_cond+0x587/0x1700 kernel/smp.c:892 on_each_cpu_cond_mask+0x40/0x90 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+0x45f/0x16f0 arch/x86/mm/tlb.c:1451 flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline] ptep_clear_flush+0x148/0x170 mm/pgtable-generic.c:104 wp_page_copy mm/memory.c:3925 [inline] do_wp_page+0x12a4/0x4350 mm/memory.c:4320 handle_pte_fault mm/memory.c:6427 [inline] __handle_mm_fault+0x1ab6/0x2a00 mm/memory.c:6549 handle_mm_fault+0x36d/0xa20 mm/memory.c:6718 do_user_addr_fault+0x74c/0x12f0 arch/x86/mm/fault.c:1385 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0010:__put_user_nocheck_4+0x3/0x10 arch/x86/lib/putuser.S:104 Code: d9 0f 01 cb 89 01 31 c9 0f 01 ca e9 c7 d7 03 00 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 01 cb <89> 01 31 c9 0f 01 ca c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc900039bf9d8 EFLAGS: 00050246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000200000b36030 RDX: 0000000000080000 RSI: ffffffff89557ad1 RDI: ffff888028eaca00 RBP: ffffc900039bfd78 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000000 R13: 0000200000b36000 R14: ffffc900039bfdbc R15: 0000000000000002 ____sys_recvmsg+0x2ec/0x640 net/socket.c:2931 ___sys_recvmsg+0x16a/0x1a0 net/socket.c:2960 do_recvmmsg+0x301/0x760 net/socket.c:3055 __sys_recvmmsg net/socket.c:3129 [inline] __do_sys_recvmmsg net/socket.c:3152 [inline] __se_sys_recvmmsg net/socket.c:3145 [inline] __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3145 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0a5739cdd9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0a5829d028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007f0a57616090 RCX: 00007f0a5739cdd9 RDX: 00000000080002c1 RSI: 0000200000000040 RDI: 0000000000000006 RBP: 00007f0a57432d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0a57616128 R14: 00007f0a57616090 R15: 00007ffedda0b6c8