rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=92bc/1/0x4000000000000000 softirq=40865/40865 fqs=2 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P12285/1:b..l (detected by 0, t=10502 jiffies, g=63973, q=165 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 53 Comm: kworker/1:1H Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: 0x0 (kblockd) RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:84 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline] RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline] RIP: 0010:kasan_check_range+0x92/0x290 mm/kasan/generic.c:189 Code: 49 83 ff 10 7f 29 4d 85 ff 0f 84 38 01 00 00 4c 89 cb 48 f7 d3 4c 01 f3 41 80 3b 00 0f 85 86 01 00 00 49 ff c3 48 ff c3 75 ee 18 01 00 00 44 89 dd 83 e5 07 0f 84 b5 00 00 00 41 80 3b 00 4d RSP: 0018:ffffc900001e08b0 EFLAGS: 00000056 RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8164079e RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90b10248 RBP: ffffc900001e0b10 R08: ffffffff90b1024f R09: 1ffffffff2162049 R10: dffffc0000000000 R11: fffffbfff216204a R12: dffffc0000000001 R13: ffff88801da9c700 R14: 1ffffffff2162049 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000001b000 CR3: 0000000028e32000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: instrument_atomic_read include/linux/instrumented.h:72 [inline] _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] hlock_class kernel/locking/lockdep.c:228 [inline] check_wait_context kernel/locking/lockdep.c:4753 [inline] __lock_acquire+0x92e/0x7c40 kernel/locking/lockdep.c:5013 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162 debug_object_deactivate+0x63/0x380 lib/debugobjects.c:810 debug_hrtimer_deactivate kernel/time/hrtimer.c:453 [inline] __run_hrtimer kernel/time/hrtimer.c:1719 [inline] __hrtimer_run_queues+0x2d8/0xc90 kernel/time/hrtimer.c:1815 hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline] __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:finish_task_switch+0x267/0x8e0 kernel/sched/core.c:5125 Code: d6 08 85 c0 0f 84 38 01 00 00 48 85 db 0f 85 57 01 00 00 e9 e7 04 00 00 4c 89 e7 e8 93 b1 e0 08 e8 2e 11 2f 00 fb 4c 8b 65 b8 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 RSP: 0018:ffffc90000be7ba0 EFLAGS: 00000286 RAX: a5229ad280b29000 RBX: 0000000000000000 RCX: a5229ad280b29000 RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: ffffffff8adf5de0 RBP: ffffc90000be7bf0 R08: ffff8880b8e3ad03 R09: 1ffff110171c75a0 R10: dffffc0000000000 R11: ffffed10171c75a1 R12: ffff88801da9bc00 R13: ffff8880b8f3ba48 R14: dffffc0000000000 R15: ffff8880b8f3b7d0 context_switch kernel/sched/core.c:5249 [inline] __schedule+0x1087/0x4030 kernel/sched/core.c:6563 schedule+0xb9/0x180 kernel/sched/core.c:6639 worker_thread+0xf5a/0x12a0 kernel/workqueue.c:2460 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 task:syz.8.2046 state:R running task stack:26192 pid:12285 ppid:11239 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5246 [inline] __schedule+0x107f/0x4030 kernel/sched/core.c:6563 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6732 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6756 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34 vprintk_emit+0x5e9/0x6a0 kernel/printk/printk.c:2304 _printk+0xda/0x130 kernel/printk/printk.c:2328 blk_print_req_error+0x175/0x210 block/blk-mq.c:798 blk_update_request+0xb7e/0xdf0 block/blk-mq.c:911 blk_mq_end_request block/blk-mq.c:1052 [inline] blk_mq_try_issue_directly+0x19b/0x1e0 block/blk-mq.c:2725 blk_mq_submit_bio+0x135f/0x2100 block/blk-mq.c:3058 __submit_bio+0x1a2/0x290 block/blk-core.c:591 __submit_bio_noacct_mq block/blk-core.c:668 [inline] submit_bio_noacct_nocheck+0x79b/0xaa0 block/blk-core.c:697 submit_bh fs/buffer.c:2707 [inline] __bread_slow fs/buffer.c:1177 [inline] __bread_gfp+0x1bb/0x330 fs/buffer.c:1370 sb_bread include/linux/buffer_head.h:338 [inline] udf_tread fs/udf/misc.c:-1 [inline] udf_read_tagged+0x123/0xe50 fs/udf/misc.c:219 udf_check_anchor_block+0x1e7/0x6a0 fs/udf/super.c:1889 udf_scan_anchors+0x52c/0x640 fs/udf/super.c:1967 udf_find_anchor fs/udf/super.c:1985 [inline] udf_load_vrs+0x1a1/0xb00 fs/udf/super.c:2050 udf_fill_super+0x69e/0x1930 fs/udf/super.c:2228 mount_bdev+0x28a/0x3c0 fs/super.c:1443 legacy_get_tree+0xe6/0x180 fs/fs_context.c:632 vfs_get_tree+0x88/0x270 fs/super.c:1573 do_new_mount+0x247/0xa40 fs/namespace.c:3078 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f958639e0d9 RSP: 002b:00007f95872a2028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f9586626090 RCX: 00007f958639e0d9 RDX: 00002000000001c0 RSI: 0000200000000100 RDI: 0000200000000400 RBP: 00007f9586435024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000008000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9586626128 R14: 00007f9586626090 R15: 00007ffdedd871c8 rcu: rcu_preempt kthread starved for 10487 jiffies! g63973 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:26800 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5246 [inline] __schedule+0x107f/0x4030 kernel/sched/core.c:6563 schedule+0xb9/0x180 kernel/sched/core.c:6639 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 PID: 4573 Comm: kworker/u4:9 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:check_kcov_mode kernel/kcov.c:193 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:216 Code: 14 41 80 7e 65 8b 15 15 41 80 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc RSP: 0018:ffffc900056377f8 EFLAGS: 00000246 RAX: ffffffff81773243 RBX: dffffc0000000000 RCX: ffff88802e111e00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90005637960 R08: ffffffff90b10247 R09: 1ffffffff2162048 R10: dffffc0000000000 R11: fffffbfff2162049 R12: 1ffff110171e8219 R13: ffff8880b8e3bdc0 R14: 0000000000000001 R15: ffff8880b8f410c8 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7e123f643c CR3: 000000000c88e000 CR4: 00000000003506f0 Call Trace: csd_lock_wait kernel/smp.c:424 [inline] smp_call_function_many_cond+0x1163/0x1250 kernel/smp.c:998 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:1574 [inline] text_poke_bp_batch+0x2b7/0x850 arch/x86/kernel/alternative.c:1774 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline] text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1972 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:207 static_key_enable+0x16/0x20 kernel/jump_label.c:220 toggle_allocation_gate+0xba/0x470 mm/kfence/core.c:821 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295