rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=27161, q=1182 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10500 (4294969791-4294959291), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10500 jiffies! g27161 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:26824 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5396 [inline] __schedule+0x16f5/0x4d00 kernel/sched/core.c:6785 __schedule_loop kernel/sched/core.c:6863 [inline] schedule+0x165/0x360 kernel/sched/core.c:6878 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 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: 8617 Comm: udevd Not tainted 6.15.0-rc7-next-20250523-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:lock_acquire+0xe/0x360 kernel/locking/lockdep.c:5831 Code: 98 29 c9 09 cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 41 57 41 56 41 55 41 54 53 <48> 83 ec 60 4d 89 ce 45 89 c7 41 89 cc 89 54 24 04 89 f3 49 89 fd RSP: 0018:ffffc90000a08ba0 EFLAGS: 00000046 RAX: 0000000000010002 RBX: ffffffff99cafb58 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff99cafb70 RBP: ffffc90000a08c78 R08: 0000000000000001 R09: 0000000000000000 R10: ffffc90000a08ca0 R11: fffff52000141196 R12: dffffc0000000000 R13: dffffc0000000000 R14: 0000000000000802 R15: 1ffff9200014117c FS: 0000000000000000(0000) GS:ffff888125d56000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f0095226000 CR3: 0000000077088000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 debug_object_activate+0xbb/0x420 lib/debugobjects.c:818 debug_hrtimer_activate kernel/time/hrtimer.c:445 [inline] debug_activate kernel/time/hrtimer.c:484 [inline] enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1088 __run_hrtimer kernel/time/hrtimer.c:1778 [inline] __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0x175/0x360 kernel/locking/lockdep.c:5875 Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 4b 7e fe 10 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e RSP: 0018:ffffc9001043f118 EFLAGS: 00000206 RAX: dfbd3de38de11600 RBX: 0000000000000000 RCX: dfbd3de38de11600 RDX: 0000000000000000 RSI: ffffffff8db6b987 RDI: ffffffff8be29300 RBP: ffffffff81728a45 R08: 0000000000000000 R09: ffffffff81728a45 R10: ffffc9001043f2d8 R11: ffffffff81ace0c0 R12: 0000000000000002 R13: ffffffff8e13f140 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xc2/0x2390 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4358 kmalloc_noprof include/linux/slab.h:905 [inline] slab_free_hook mm/slub.c:2332 [inline] slab_free mm/slub.c:4642 [inline] kmem_cache_free+0x166/0x400 mm/slub.c:4744 exit_mmap+0x53f/0xb50 mm/mmap.c:1309 __mmput+0x118/0x420 kernel/fork.c:1121 exec_mmap+0x6ac/0x7d0 fs/exec.c:896 begin_new_exec+0x129c/0x2120 fs/exec.c:1151 load_elf_binary+0x96a/0x2790 fs/binfmt_elf.c:995 search_binary_handler fs/exec.c:1665 [inline] exec_binprm fs/exec.c:1697 [inline] bprm_execve+0x99c/0x1440 fs/exec.c:1749 do_execveat_common+0x510/0x6a0 fs/exec.c:1855 do_execve fs/exec.c:1929 [inline] __do_sys_execve fs/exec.c:2005 [inline] __se_sys_execve fs/exec.c:2000 [inline] __x64_sys_execve+0x94/0xb0 fs/exec.c:2000 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0094af2107 Code: Unable to access opcode bytes at 0x7f0094af20dd. RSP: 002b:00007ffdd730b7e8 EFLAGS: 00000206 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 000055be877b7140 RCX: 00007f0094af2107 RDX: 000055be95959f30 RSI: 00007ffdd730b900 RDI: 00007ffdd730bd00 RBP: 0000000000000009 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000008 R11: 0000000000000206 R12: 000055be95959f30 R13: 00007ffdd730b900 R14: 000000000000000e R15: 000000000000000b