rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (0 ticks this GP) idle=b63/1/0x4000000000000002 softirq=32192/32192 fqs=0 (detected by 1, t=10502 jiffies, g=43517, q=48) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 12900 Comm: syz.6.2207 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x0/0x80 kernel/kcov.c:294 Code: 28 4d 39 ca 77 22 89 ff 89 f6 4a c7 44 02 08 03 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 90 <48> 8b 04 24 65 48 8b 0d 14 4a 89 7e 65 8b 15 15 4a 89 7e 81 e2 00 RSP: 0018:ffffc900036befe0 EFLAGS: 00000046 RAX: ffffffff81850756 RBX: ffff8880b903b1f0 RCX: ffff888028679dc0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffff8880b903b1fb R09: 1ffff1101720763f R10: dffffc0000000000 R11: ffffed1017207640 R12: 0000000000000000 R13: dffffc0000000001 R14: 0000000000000000 R15: ffff8880b903b1f8 FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5d7370d201 CR3: 0000000065778000 CR4: 00000000003506f0 DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: irq_work_claim kernel/irq_work.c:40 [inline] irq_work_queue_on+0xe3/0x220 kernel/irq_work.c:98 rcu_read_unlock_special+0x37b/0x4a0 kernel/rcu/tree_plugin.h:667 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock include/linux/rcupdate.h:772 [inline] __perf_event_output kernel/events/core.c:7813 [inline] perf_event_output_forward+0x255/0x2e0 kernel/events/core.c:7822 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713 RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674 Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 e2 f0 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08 RSP: 0018:ffffc900036bf760 EFLAGS: 00000206 RAX: 4b7af06c13e10c00 RBX: 1ffff920006d7ef0 RCX: 4b7af06c13e10c00 RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800 RBP: ffffc900036bf830 R08: ffffffff901d30c7 R09: 1ffffffff203a618 R10: dffffc0000000000 R11: fffffbfff203a619 R12: ffffffff8c322f00 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock include/linux/rcupdate.h:772 [inline] __unlock_page_memcg+0xea/0x100 mm/memcontrol.c:2093 zap_pte_range mm/memory.c:1384 [inline] zap_pmd_range mm/memory.c:1505 [inline] zap_pud_range mm/memory.c:1534 [inline] zap_p4d_range mm/memory.c:1555 [inline] unmap_page_range+0xf96/0x2500 mm/memory.c:1576 unmap_vmas+0x131/0x250 mm/memory.c:1653 exit_mmap+0x3b9/0x640 mm/mmap.c:3216 __mmput+0x115/0x3b0 kernel/fork.c:1127 exit_mm+0x588/0x6e0 kernel/exit.c:550 do_exit+0x5a9/0x20c0 kernel/exit.c:870 do_group_exit+0x12e/0x300 kernel/exit.c:997 __do_sys_exit_group kernel/exit.c:1008 [inline] __se_sys_exit_group kernel/exit.c:1006 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fc9a9031799 Code: Unable to access opcode bytes at RIP 0x7fc9a903176f. RSP: 002b:00007ffe027af958 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc9a9031799 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffe027af9bc R08: 0000000000000000 R09: 00000000000927c0 R10: 0000000000000006 R11: 0000000000000246 R12: 000000000000011c R13: 00000000000927c0 R14: 000000000005bdc7 R15: 00007ffe027afa10 rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g43517 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=24603 rcu: rcu_preempt kthread starved for 10502 jiffies! g43517 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27376 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 12900 Comm: syz.6.2207 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:hlock_class kernel/locking/lockdep.c:197 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4686 [inline] RIP: 0010:__lock_acquire+0x532/0x7d10 kernel/locking/lockdep.c:4962 Code: 81 e3 ff 1f 00 00 41 c1 ed 03 41 81 e5 f8 03 00 00 49 8d bd c0 30 1d 90 be 08 00 00 00 e8 46 24 61 00 48 0f a3 1d 4e 25 c0 0e <73> 1f 48 8d 04 5b c1 e0 06 48 8d 98 80 af b5 8f 48 ba 00 00 00 00 RSP: 0018:ffffc900036bed80 EFLAGS: 00000057 RAX: 0000000000000001 RBX: 0000000000000015 RCX: ffffffff815d0b6a RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901d30c0 RBP: ffffc900036befd0 R08: ffffffff901d30c7 R09: 1ffffffff203a618 R10: dffffc0000000000 R11: fffffbfff203a619 R12: ffff88802867a920 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88802867a900 FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5d7370d201 CR3: 0000000065778000 CR4: 00000000003506f0 DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313 rcu_read_lock include/linux/rcupdate.h:740 [inline] __perf_event_output kernel/events/core.c:7800 [inline] perf_event_output_forward+0xbc/0x2e0 kernel/events/core.c:7822 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713 RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674 Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 e2 f0 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08 RSP: 0018:ffffc900036bf760 EFLAGS: 00000206 RAX: 4b7af06c13e10c00 RBX: 1ffff920006d7ef0 RCX: 4b7af06c13e10c00 RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800 RBP: ffffc900036bf830 R08: ffffffff901d30c7 R09: 1ffffffff203a618 R10: dffffc0000000000 R11: fffffbfff203a619 R12: ffffffff8c322f00 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock include/linux/rcupdate.h:772 [inline] __unlock_page_memcg+0xea/0x100 mm/memcontrol.c:2093 zap_pte_range mm/memory.c:1384 [inline] zap_pmd_range mm/memory.c:1505 [inline] zap_pud_range mm/memory.c:1534 [inline] zap_p4d_range mm/memory.c:1555 [inline] unmap_page_range+0xf96/0x2500 mm/memory.c:1576 unmap_vmas+0x131/0x250 mm/memory.c:1653 exit_mmap+0x3b9/0x640 mm/mmap.c:3216 __mmput+0x115/0x3b0 kernel/fork.c:1127 exit_mm+0x588/0x6e0 kernel/exit.c:550 do_exit+0x5a9/0x20c0 kernel/exit.c:870 do_group_exit+0x12e/0x300 kernel/exit.c:997 __do_sys_exit_group kernel/exit.c:1008 [inline] __se_sys_exit_group kernel/exit.c:1006 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fc9a9031799 Code: Unable to access opcode bytes at RIP 0x7fc9a903176f. RSP: 002b:00007ffe027af958 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc9a9031799 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffe027af9bc R08: 0000000000000000 R09: 00000000000927c0 R10: 0000000000000006 R11: 0000000000000246 R12: 000000000000011c R13: 00000000000927c0 R14: 000000000005bdc7 R15: 00007ffe027afa10