rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-....: (10026 ticks this GP) idle=43dc/1/0x4000000000000000 softirq=68043/77259 fqs=508 rcu: hardirqs softirqs csw/system rcu: number: 7 6 2 rcu: cputime: 0 4782 19 ==> 4790(ms) rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P1159/1:b..l P12397/1:b..l rcu: (detected by 1, t=12759 jiffies, g=49557, q=666 ncpus=2) task:syz.0.1493 state:R running task stack:26360 pid:12397 tgid:12395 ppid:5844 task_flags:0x400140 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7145 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] wp_page_copy mm/memory.c:3653 [inline] do_wp_page+0x177b/0x4f00 mm/memory.c:4013 handle_pte_fault mm/memory.c:6068 [inline] __handle_mm_fault+0x1b2d/0x2a50 mm/memory.c:6195 handle_mm_fault+0x589/0xd10 mm/memory.c:6364 do_user_addr_fault+0x7a6/0x1370 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x5c/0xb0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 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 47 69 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:ffffc90003aff9f8 EFLAGS: 00050293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000020000018b030 RDX: ffff88805e5c2440 RSI: ffffffff89635d93 RDI: 0000000000000005 RBP: ffffc90003affd98 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000000 R13: 000020000018b000 R14: ffffc90003affddc R15: 0000000000000002 ____sys_recvmsg+0x2ee/0x6b0 net/socket.c:2847 ___sys_recvmsg+0x114/0x1a0 net/socket.c:2876 do_recvmmsg+0x2fe/0x750 net/socket.c:2971 __sys_recvmmsg net/socket.c:3045 [inline] __do_sys_recvmmsg net/socket.c:3068 [inline] __se_sys_recvmmsg net/socket.c:3061 [inline] __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3061 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd0a4b8eba9 RSP: 002b:00007fd0a597c038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007fd0a4dd6090 RCX: 00007fd0a4b8eba9 RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000004 RBP: 00007fd0a4c11e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd0a4dd6128 R14: 00007fd0a4dd6090 R15: 00007ffe4f4cbeb8 task:kworker/u8:7 state:R running task stack:23560 pid:1159 tgid:1159 ppid:2 task_flags:0x4208060 flags:0x00004000 Workqueue: events_unbound cfg80211_wiphy_work Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288 irqentry_exit+0x36/0x90 kernel/entry/common.c:197 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline] RIP: 0010:lock_acquire+0x4e/0x350 kernel/locking/lockdep.c:5831 Code: 48 8b 05 bd e6 3e 12 48 89 44 24 30 31 c0 66 90 65 8b 05 d9 e6 3e 12 83 f8 07 0f 87 bc 02 00 00 89 c0 48 0f a3 05 22 a2 13 0f <0f> 82 74 02 00 00 8b 35 da d3 13 0f 85 f6 0f 85 8d 00 00 00 48 8b RSP: 0018:ffffc90003e2f600 EFLAGS: 00000297 RAX: 0000000000000001 RBX: ffffffff8e5c1260 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e5c1260 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000003 R11: 00000000000082cd R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 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+0xd1/0x20a0 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2422 [inline] slab_free mm/slub.c:4695 [inline] kmem_cache_free+0x2d1/0x4d0 mm/slub.c:4797 skb_kfree_head net/core/skbuff.c:1045 [inline] skb_kfree_head net/core/skbuff.c:1042 [inline] skb_free_head+0x1b7/0x210 net/core/skbuff.c:1059 skb_release_data+0x795/0x9e0 net/core/skbuff.c:1086 skb_release_all net/core/skbuff.c:1151 [inline] __kfree_skb net/core/skbuff.c:1165 [inline] sk_skb_reason_drop+0x129/0x1a0 net/core/skbuff.c:1203 kfree_skb_reason include/linux/skbuff.h:1275 [inline] kfree_skb include/linux/skbuff.h:1284 [inline] ieee80211_iface_work+0x435/0x1360 net/mac80211/iface.c:1755 cfg80211_wiphy_work+0x2c7/0x580 net/wireless/core.c:435 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 2893 jiffies! g49557 f0x0 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:27368 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 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: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: cc 61 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 53 b3 15 00 fb f4 8c 09 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffc90000197df8 EFLAGS: 000002c2 RAX: 000000000255538b RBX: 0000000000000001 RCX: ffffffff8b945c29 RDX: 0000000000000000 RSI: ffffffff8de522e8 RDI: ffffffff8c162d80 RBP: ffffed1003c5d488 R08: 0000000000000001 R09: ffffed10170a6655 R10: ffff8880b85332ab R11: 0000000000000000 R12: 0000000000000001 R13: ffff88801e2ea440 R14: ffffffff90ab6b90 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881247b5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f285b8ef102 CR3: 000000005b3c1000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:757 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x148