rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=a0b/1/0x4000000000000000 softirq=124822/124822 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4520 (detected by 0, t=10502 jiffies, g=175549, q=748) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 4520 Comm: syz.7.6951 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:native_apic_msr_eoi_write+0xb/0x10 arch/x86/include/asm/apic.h:214 Code: 8b 06 bf f0 03 00 00 89 de 5b 41 5e 41 5f ff e0 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b9 0b 08 00 00 31 c0 31 d2 0f 30 0f 1f 40 00 81 ff cf 00 00 00 7f 0c 83 ff 20 74 2a 83 ff 30 74 RSP: 0018:ffffc90000dd0fd8 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffffffff8be3d9c8 RCX: 000000000000080b RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000000000b0 RBP: 0000000000000000 R08: ffffffff8f103048 R09: ffffffff8f103058 R10: ffffffff8f103050 R11: ffffffff8f103043 R12: 0000000000000000 R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f89d79d7270 CR3: 0000000060697000 CR4: 00000000003506e0 DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000200000000300 DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: apic_eoi arch/x86/include/asm/apic.h:400 [inline] ack_APIC_irq arch/x86/include/asm/apic.h:446 [inline] __sysvec_irq_work+0x51/0x240 arch/x86/kernel/irq_work.c:19 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline] sysvec_irq_work+0x98/0xc0 arch/x86/kernel/irq_work.c:17 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 02 20 9d 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:ffffc90002daf840 EFLAGS: 00000206 RAX: eeff6810cd867400 RBX: 1ffff920005b5f0c RCX: eeff6810cd867400 RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4200 RBP: ffffc90002daf918 R08: ffffffff901ee0cf R09: 1ffffffff203dc19 R10: dffffc0000000000 R11: fffffbfff203dc1a R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000246 R15: ffffffff8c3234a0 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock+0x85/0x90 include/linux/rcupdate.h:772 dput+0xc0/0x1a0 fs/dcache.c:886 __fput+0x5a5/0x8c0 fs/file_table.c:319 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x635/0x2110 kernel/exit.c:890 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004 get_signal+0x7eb/0x12e0 kernel/signal.c:2909 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7ff12314c0d9 Code: Unable to access opcode bytes at RIP 0x7ff12314c0af. RSP: 002b:00007ff121383028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: 00000000000000d8 RBX: 00007ff1233d4090 RCX: 00007ff12314c0d9 RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000007 RBP: 00007ff1231e3024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff1233d4128 R14: 00007ff1233d4090 R15: 00007ffc18f3cc78 task:syz.7.6951 state:R running task stack:24752 pid: 4520 ppid: 2044 flags:0x0000400a Call Trace: rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g175549 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=72416 rcu: rcu_preempt kthread starved for 10502 jiffies! g175549 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27008 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 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/0x11f0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145 kthread+0x42e/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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 4520 Comm: syz.7.6951 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:205 Code: 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d 70 13 12 0c 48 89 de 5b e9 47 5a 44 00 00 00 cc cc 00 00 cc 48 8b 04 24 <65> 48 8b 0d 04 73 89 7e 65 8b 15 05 73 89 7e 81 e2 00 01 ff 00 74 RSP: 0018:ffffc90002daf678 EFLAGS: 00000806 RAX: ffffffff817f1de0 RBX: dffffc0000000000 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: ffffffff89e00e46 RDI: ffffffff8c369e20 RBP: ffffc90002daf748 R08: ffff8880b913b30b R09: 1ffff11017227661 R10: dffffc0000000000 R11: ffffed1017227662 R12: 0000000000000001 R13: ffffffff8c369e20 R14: ffffffff89e00e46 R15: 1ffff920005b5ed4 FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f89d79d7270 CR3: 0000000060697000 CR4: 00000000003506e0 DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000200000000300 DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: perf_trace_preemptirq_template+0x80/0x360 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 02 20 9d 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:ffffc90002daf840 EFLAGS: 00000206 RAX: eeff6810cd867400 RBX: 1ffff920005b5f0c RCX: eeff6810cd867400 RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4200 RBP: ffffc90002daf918 R08: ffffffff901ee0cf R09: 1ffffffff203dc19 R10: dffffc0000000000 R11: fffffbfff203dc1a R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000246 R15: ffffffff8c3234a0 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock+0x85/0x90 include/linux/rcupdate.h:772 dput+0xc0/0x1a0 fs/dcache.c:886 __fput+0x5a5/0x8c0 fs/file_table.c:319 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x635/0x2110 kernel/exit.c:890 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004 get_signal+0x7eb/0x12e0 kernel/signal.c:2909 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7ff12314c0d9 Code: Unable to access opcode bytes at RIP 0x7ff12314c0af. RSP: 002b:00007ff121383028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: 00000000000000d8 RBX: 00007ff1233d4090 RCX: 00007ff12314c0d9 RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000007 RBP: 00007ff1231e3024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff1233d4128 R14: 00007ff1233d4090 R15: 00007ffc18f3cc78