rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5820/1:b..l P17625/1:b..l rcu: (detected by 0, t=10502 jiffies, g=89977, q=893 ncpus=2) task:syz.1.2738 state:R running task stack:23904 pid:17625 tgid:17624 ppid:5819 task_flags:0x400040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5295 [inline] __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7235 irqentry_exit+0x599/0x620 kernel/entry/common.c:239 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline] RIP: 0010:write_comp_data kernel/kcov.c:245 [inline] RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x8/0x90 kernel/kcov.c:321 Code: 89 44 11 20 e9 c4 a2 4a ff cc 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d 98 21 56 11 65 8b 15 b9 21 56 11 81 e2 00 01 ff 00 74 RSP: 0018:ffffc90017627830 EFLAGS: 00000202 RAX: ffffffff8bab2141 RBX: ffff88805a2a6102 RCX: ffff888033f5db80 RDX: 0000000000000003 RSI: 0000000000000002 RDI: 0000000000000002 RBP: 0000000000000001 R08: 000000000001ffff R09: 0000000000400000 R10: 0000000000400008 R11: fffff52002ec4f2b R12: 0000000000000002 R13: ffffc90017627938 R14: ffffc90017627920 R15: 1ffff92002ec4f27 xa_is_internal include/linux/xarray.h:175 [inline] xa_is_node include/linux/xarray.h:1270 [inline] xas_start+0x2c1/0x770 lib/xarray.c:192 xas_load+0x2c/0x5b0 lib/xarray.c:239 filemap_get_entry+0x185/0x320 mm/filemap.c:1895 shmem_get_folio_gfp+0x243/0x1670 mm/shmem.c:2491 shmem_get_folio mm/shmem.c:2673 [inline] shmem_write_begin+0x16c/0x330 mm/shmem.c:3327 generic_perform_write+0x2e2/0x8f0 mm/filemap.c:4314 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3502 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x61d/0xb90 fs/read_write.c:688 ksys_write+0x150/0x270 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd91535cfce RSP: 002b:00007fd9162fada8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fd9162fb6c0 RCX: 00007fd91535cfce RDX: 0000000001000000 RSI: 00007fd90b000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003 R13: 00007fd9162faee0 R14: 00007fd9162faea0 R15: 00007fd90b000000 task:syz-executor state:R running task stack:22496 pid:5820 tgid:5820 ppid:5816 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5295 [inline] __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7235 irqentry_exit+0x599/0x620 kernel/entry/common.c:239 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__kasan_check_byte+0x14/0x40 mm/kasan/common.c:573 Code: 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 41 56 53 48 89 f3 49 89 fe e8 8e 15 00 00 84 c0 <75> 16 be 01 00 00 00 4c 89 f7 31 d2 48 89 d9 89 c3 e8 06 05 00 00 RSP: 0018:ffffc900038a75c8 EFLAGS: 00000202 RAX: 0000000000000001 RBX: ffffffff81767a62 RCX: 0000000080000001 RDX: 0000000000000000 RSI: ffffffff81767a62 RDI: 1ffffffff1cec05c RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffffff81b0bb80 R12: 0000000000000002 R13: ffffffff8e7602e0 R14: ffffffff8e7602e0 R15: 0000000000000000 kasan_check_byte include/linux/kasan.h:402 [inline] lock_acquire+0x79/0x2e0 kernel/locking/lockdep.c:5842 rcu_lock_acquire include/linux/rcupdate.h:312 [inline] rcu_read_lock include/linux/rcupdate.h:850 [inline] class_rcu_constructor include/linux/rcupdate.h:1193 [inline] unwind_next_frame+0xc2/0x23c0 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978 vfree+0x25a/0x400 mm/vmalloc.c:3479 __do_replace+0x84c/0x9a0 net/ipv6/netfilter/ip6_tables.c:1107 do_replace net/ipv6/netfilter/ip6_tables.c:1158 [inline] do_ip6t_set_ctl+0xb4e/0xe10 net/ipv6/netfilter/ip6_tables.c:1644 nf_setsockopt+0x26f/0x290 net/netfilter/nf_sockopt.c:101 do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2322 __sys_setsockopt net/socket.c:2347 [inline] __do_sys_setsockopt net/socket.c:2353 [inline] __se_sys_setsockopt net/socket.c:2350 [inline] __x64_sys_setsockopt+0x13d/0x1b0 net/socket.c:2350 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6b56f9dfda RSP: 002b:00007fffb3f3b0c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007fffb3f3b150 RCX: 00007f6b56f9dfda RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003 RBP: 0000000000000003 R08: 0000000000000558 R09: 0000000000000000 R10: 00007f6b571e7be0 R11: 0000000000000202 R12: 00007f6b571e7b80 R13: 00007fffb3f3b0ec R14: 0000000000000000 R15: 00007f6b571e8fc0 rcu: rcu_preempt kthread starved for 5792 jiffies! g89977 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:27656 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5295 [inline] __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908 __schedule_loop kernel/sched/core.c:6990 [inline] schedule+0x164/0x360 kernel/sched/core.c:7005 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63 Code: 3e 6d 02 e9 8e c2 62 f5 cc cc cc 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 c3 e0 1b 00 fb f4 67 c2 62 f5 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffffff8e407dc0 EFLAGS: 00000242 RAX: 000000000121c2a1 RBX: ffffffff819a886d RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8def3648 RDI: ffffffff8c27b080 RBP: ffffffff8e407eb0 R08: ffff8880b863395b R09: 1ffff110170c672b R10: dffffc0000000000 R11: ffffed10170c672c R12: ffffffff901190b0 R13: 1ffffffff1c929d8 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888125464000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6e638c205d CR3: 0000000028148000 CR4: 0000000000350ef0 Call Trace: arch_safe_halt arch/x86/kernel/process.c:766 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x1bd/0x500 kernel/sched/idle.c:332 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:430 rest_init+0x2de/0x300 init/main.c:760 start_kernel+0x385/0x3d0 init/main.c:1210 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147