rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P10011/2:b..l rcu: (detected by 1, t=10502 jiffies, g=31869, q=1105 ncpus=2) task:syz.3.807 state:R running task stack:25016 pid:10011 tgid:10009 ppid:5817 task_flags:0x2040044c flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__sanitizer_cov_trace_cmp4+0x8/0x20 kernel/kcov.c:288 Code: bf 02 00 00 00 e9 18 ff ff ff 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 0c 24 <89> f2 89 fe bf 04 00 00 00 e9 ea fe ff ff 66 2e 0f 1f 84 00 00 00 RSP: 0018:ffffc900037f6c38 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 000000000000022e RCX: ffffffff81cebac3 RDX: ffff88802c678000 RSI: 000000000000022e RDI: 000000000000022e RBP: 0000000000000000 R08: 0000000000000006 R09: 00007f59e2b8f749 R10: ffffffffa0201660 R11: ffff88802c678b30 R12: 00007f59e2b8f749 R13: dffffc0000000000 R14: 000000000000022e R15: ffffffffa0201660 latch_tree_find include/linux/rbtree_latch.h:211 [inline] bpf_ksym_find+0x103/0x1c0 kernel/bpf/core.c:712 is_bpf_text_address+0x58/0x1a0 kernel/bpf/core.c:745 kernel_text_address kernel/extable.c:125 [inline] kernel_text_address+0x8d/0x100 kernel/extable.c:94 __kernel_text_address+0xd/0x40 kernel/extable.c:79 unwind_get_return_address+0x59/0xa0 arch/x86/kernel/unwind_orc.c:369 arch_stack_walk+0xa6/0x100 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_save_track+0x14/0x30 mm/kasan/common.c:77 poison_kmalloc_redzone mm/kasan/common.c:397 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:414 kmalloc_noprof include/linux/slab.h:957 [inline] slab_free_hook mm/slub.c:2492 [inline] slab_free mm/slub.c:6663 [inline] kmem_cache_free+0x147/0x770 mm/slub.c:6774 mempool_free+0xde/0x130 mm/mempool.c:712 bio_put_percpu_cache block/bio.c:806 [inline] bio_put+0x355/0x5b0 block/bio.c:825 bio_endio+0x751/0x8a0 block/bio.c:1673 blk_update_request+0x914/0x15c0 block/blk-mq.c:1006 blk_mq_end_request+0x59/0x430 block/blk-mq.c:1168 blk_mq_complete_request block/blk-mq.c:1346 [inline] blk_mq_complete_request+0x8b/0xb0 block/blk-mq.c:1343 nullb_complete_cmd drivers/block/null_blk/main.c:1402 [inline] null_handle_cmd drivers/block/null_blk/main.c:1454 [inline] null_queue_rq+0xb69/0xfd0 drivers/block/null_blk/main.c:1693 null_queue_rqs+0xe9/0x2f0 drivers/block/null_blk/main.c:1707 __blk_mq_flush_list block/blk-mq.c:2847 [inline] __blk_mq_flush_list+0x9a/0xc0 block/blk-mq.c:2843 blk_mq_dispatch_queue_requests+0x184/0x7b0 block/blk-mq.c:2892 blk_mq_flush_plug_list+0x1f2/0x600 block/blk-mq.c:2980 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225 blk_finish_plug block/blk-core.c:1252 [inline] blk_finish_plug+0x53/0xa0 block/blk-core.c:1249 blkdev_writepages+0xe9/0x140 block/fops.c:492 do_writepages+0x27a/0x600 mm/page-writeback.c:2598 filemap_writeback+0x225/0x2d0 mm/filemap.c:387 filemap_fdatawrite_range mm/filemap.c:412 [inline] filemap_write_and_wait_range mm/filemap.c:684 [inline] filemap_write_and_wait_range+0xa6/0x130 mm/filemap.c:675 filemap_write_and_wait include/linux/pagemap.h:65 [inline] sync_blockdev block/bdev.c:277 [inline] sync_blockdev block/bdev.c:273 [inline] bdev_release+0x4d3/0x6d0 block/bdev.c:1143 blkdev_release+0x15/0x20 block/fops.c:710 __fput+0x402/0xb70 fs/file_table.c:468 task_work_run+0x150/0x240 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x87f/0x2bd0 kernel/exit.c:971 do_group_exit+0xd3/0x2a0 kernel/exit.c:1112 get_signal+0x2671/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x8c/0x540 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f59e2b8f749 RSP: 002b:00007f59e39830e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f59e2de6098 RCX: 00007f59e2b8f749 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f59e2de6098 RBP: 00007f59e2de6090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f59e2de6128 R14: 00007fff47d93500 R15: 00007fff47d935e8 rcu: rcu_preempt kthread starved for 10373 jiffies! g31869 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:28488 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: 06 60 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 13 59 13 00 fb f4 cc 35 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e007df8 EFLAGS: 000002c6 RAX: 00000000020bf497 RBX: 0000000000000000 RCX: ffffffff8b7706d9 RDX: 0000000000000000 RSI: ffffffff8dac200a RDI: ffffffff8bf24280 RBP: fffffbfff1c12f68 R08: 0000000000000001 R09: ffffed101708673d R10: ffff8880b84339eb R11: ffffffff8e098670 R12: 0000000000000000 R13: ffffffff8e097b40 R14: ffffffff9087f7d0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888124909000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2fd22ff8 CR3: 000000000e184000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x38d/0x510 kernel/sched/idle.c:332 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430 rest_init+0x16b/0x2b0 init/main.c:757 start_kernel+0x3ef/0x4d0 init/main.c:1206 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x148