rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=7777, q=70 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294955984-4294945481), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10504 jiffies! g7777 f0x2 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:27256 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 schedule+0xb9/0x180 kernel/sched/core.c:6638 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 PID: 4294 Comm: syz-executor278 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:check_kcov_mode kernel/kcov.c:193 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:216 Code: c4 fc 7f 7e 65 8b 15 c5 fc 7f 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc RSP: 0018:ffffc90004017c40 EFLAGS: 00000246 RAX: ffffffff8434a7f5 RBX: 0000000000000030 RCX: ffff888019ad9dc0 RDX: 0000000000000000 RSI: ffffffff8a8c23a0 RDI: ffffffff8adf0c20 RBP: ffffc90004017ec0 R08: ffffffff8e1fc32f R09: 1ffffffff1c3f865 R10: dffffc0000000000 R11: fffffbfff1c3f866 R12: dffffc0000000000 R13: ffffc90004017ff8 R14: 00007ffc0d62c230 R15: ffffc90004017e00 FS: 000055558cc2b480(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000058 CR3: 0000000077754000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: should_fail_usercopy+0x5/0x20 lib/fault-inject-usercopy.c:36 _copy_to_user+0x2c/0x130 lib/usercopy.c:37 copy_to_user include/linux/uaccess.h:169 [inline] copy_siginfo_to_user+0x1f/0x140 kernel/signal.c:3339 __setup_rt_frame arch/x86/kernel/signal.c:491 [inline] setup_rt_frame arch/x86/kernel/signal.c:784 [inline] handle_signal arch/x86/kernel/signal.c:828 [inline] arch_do_signal_or_restart+0xde5/0x1350 arch/x86/kernel/signal.c:873 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f9f261a502e Code: 08 0f 85 25 ec ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08 RSP: 002b:00007ffc0d62c6a8 EFLAGS: 00000246 RAX: fffffffffffffff7 RBX: 000055558cc2b480 RCX: 00007f9f261a502e RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000e RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9f261ef1df R13: 00007f9f261ef1b5 R14: 00007ffc0d62c740 R15: 0000000000000000