rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P11/1:b..l P9218/1:b..l P5785/1:b..l rcu: (detected by 1, t=10502 jiffies, g=41345, q=121 ncpus=2) task:syz-executor state:R running task stack:21736 pid:5785 ppid:5784 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] copy_pte_range mm/memory.c:1106 [inline] copy_pmd_range mm/memory.c:1167 [inline] copy_pud_range mm/memory.c:1204 [inline] copy_p4d_range mm/memory.c:1228 [inline] copy_page_range+0x2b7c/0x3600 mm/memory.c:1322 dup_mmap kernel/fork.c:764 [inline] dup_mm kernel/fork.c:1692 [inline] copy_mm+0x112a/0x1c20 kernel/fork.c:1741 copy_process+0x16d3/0x3d70 kernel/fork.c:2506 kernel_clone+0x21b/0x840 kernel/fork.c:2914 __do_sys_clone kernel/fork.c:3057 [inline] __se_sys_clone kernel/fork.c:3041 [inline] __x64_sys_clone+0x18c/0x1e0 kernel/fork.c:3041 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fd2bff85493 RSP: 002b:00007ffef74bd6a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd2bff85493 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 000055558f14b7d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 00000000000778da R15: 00007ffef74bd840 task:syz.4.897 state:R running task stack:25480 pid:9218 ppid:6437 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009 irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758 Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00 RSP: 0018:ffffc9000b5a7260 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: b6c2e78aaf399700 RDX: 0000000000000000 RSI: ffffffff8aaace20 RDI: ffffffff8afc71c0 RBP: ffffc9000b5a7370 R08: dffffc0000000000 R09: 1ffffffff21b4ea0 R10: dffffc0000000000 R11: fffffbfff21b4ea1 R12: 1ffff920016b4e58 R13: ffffffff8cd2fe20 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire include/linux/rcupdate.h:334 [inline] rcu_read_lock include/linux/rcupdate.h:786 [inline] percpu_ref_put_many include/linux/percpu-refcount.h:330 [inline] percpu_ref_put+0x35/0x180 include/linux/percpu-refcount.h:351 css_put include/linux/cgroup_refcnt.h:79 [inline] __mem_cgroup_charge+0x56/0x80 mm/memcontrol.c:7070 mem_cgroup_charge include/linux/memcontrol.h:686 [inline] wp_page_copy mm/memory.c:3117 [inline] do_wp_page+0x14fe/0x3630 mm/memory.c:3468 handle_pte_fault mm/memory.c:5041 [inline] __handle_mm_fault mm/memory.c:5166 [inline] handle_mm_fault+0x12d4/0x4920 mm/memory.c:5331 do_user_addr_fault+0x738/0x12e0 arch/x86/mm/fault.c:1373 handle_page_fault arch/x86/mm/fault.c:1465 [inline] exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0010:__put_user_nocheck_4+0x7/0x10 arch/x86/lib/putuser.S:98 Code: 01 ca c3 f3 0f 1e fa 48 89 cb 48 c1 fb 3f 48 09 d9 0f 01 cb 89 01 31 c9 0f 01 ca c3 90 90 90 90 90 90 90 f3 0f 1e fa 0f 01 cb <89> 01 31 c9 0f 01 ca c3 90 f3 0f 1e fa 48 89 cb 48 c1 fb 3f 48 09 RSP: 0018:ffffc9000b5a78d8 EFLAGS: 00050202 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000020000037a030 RDX: ffff888025190000 RSI: 0000000000000002 RDI: 00000000ffffffff RBP: ffffc9000b5a7a70 R08: ffffc9000b5a7687 R09: 1ffff920016b4ed0 R10: dffffc0000000000 R11: fffff520016b4ed1 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000002 R15: 000020000037a000 ____sys_recvmsg+0x388/0x5b0 net/socket.c:2827 ___sys_recvmsg+0x1b6/0x510 net/socket.c:2856 do_recvmmsg+0x360/0x7d0 net/socket.c:2950 __sys_recvmmsg net/socket.c:3029 [inline] __do_sys_recvmmsg net/socket.c:3052 [inline] __se_sys_recvmmsg net/socket.c:3045 [inline] __x64_sys_recvmmsg+0x191/0x240 net/socket.c:3045 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f9e3b98ec29 RSP: 002b:00007f9e3c8b0038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007f9e3bbd6090 RCX: 00007f9e3b98ec29 RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000004 RBP: 00007f9e3ba11e41 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9e3bbd6128 R14: 00007f9e3bbd6090 R15: 00007ffe9a3b98b8 task:kworker/u4:0 state:R running task stack:24392 pid:11 ppid:2 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009 irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:__rcu_read_unlock+0x6/0xd0 kernel/rcu/tree_plugin.h:419 Code: eb fa 89 d9 80 e1 07 80 c1 03 38 c1 7c e3 48 89 df e8 fe 75 6c 00 eb d9 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa 41 57 <41> 56 41 55 41 54 53 49 bf 00 00 00 00 00 fc ff df 65 48 8b 3d f1 RSP: 0018:ffffc90000107b50 EFLAGS: 00000293 RAX: ffffffff8a369951 RBX: ffff88802dc426c0 RCX: ffff888019e7bc00 RDX: 0000000000000000 RSI: ffffffff8afc71a0 RDI: ffffffff8afc7160 RBP: fffffffffffffe38 R08: dffffc0000000000 R09: 1ffffffff21b4ea0 R10: dffffc0000000000 R11: fffffbfff21b4ea1 R12: dffffc0000000000 R13: ffffffff8a369812 R14: ffff888030848c80 R15: 00000000000001eb rcu_read_unlock include/linux/rcupdate.h:818 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline] batadv_nc_worker+0x282/0x610 net/batman-adv/network-coding.c:719 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: rcu_preempt kthread starved for 10356 jiffies! g41345 f0x0 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:27496 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 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: 0 Comm: swapper/0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148 Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d a3 e8 39 00 f3 0f 1e fa fb f4 cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56 RSP: 0018:ffffffff8ca07d80 EFLAGS: 000002c2 RAX: dc0164cc2ae7a700 RBX: ffffffff8161925b RCX: dc0164cc2ae7a700 RDX: 0000000000000001 RSI: ffffffff8aaabca0 RDI: ffffffff8afc71c0 RBP: ffffffff8ca07eb8 R08: ffff8880b8e36b2b R09: 1ffff110171c6d65 R10: dffffc0000000000 R11: ffffed10171c6d66 R12: ffffffff8e4a91a8 R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1952670 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000037a030 CR3: 000000002ce35000 CR4: 00000000003506f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1eb/0x510 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 rest_init+0x2e2/0x300 init/main.c:732 arch_call_rest_init+0xe/0x10 init/main.c:829 start_kernel+0x459/0x4e0 init/main.c:1074 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b