rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=d514/1/0x4000000000000000 softirq=200546/200548 fqs=3 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P27894/1:b..l P20017/1:b..l rcu: (detected by 0, t=10502 jiffies, g=244097, q=686 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 27882 Comm: syz.4.5836 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:__kasan_check_write+0x0/0x20 mm/kasan/shadow.c:36 Code: 48 8b 0c 24 31 d2 e9 8f e5 ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 89 f6 48 8b 0c 24 ba 01 00 00 00 e9 5c e5 ff ff 66 66 RSP: 0018:ffffc90000a08d18 EFLAGS: 00000056 RAX: 00000000ffffff01 RBX: ffff8880b87281c0 RCX: ffffffff81a3567c RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90000a08d60 RBP: ffffc90000a08dc8 R08: ffff8880b87281c3 R09: 1ffff110170e5038 R10: dffffc0000000000 R11: ffffed10170e5039 R12: 1ffff920001411a8 R13: ffff8880b87281c8 R14: dffffc0000000000 R15: 1ffff110170e5039 FS: 0000000000000000(0000) GS:ffff88812504e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2821fa CR3: 000000000e946000 CR4: 0000000000350ef0 Call Trace: instrument_read_write include/linux/instrumented.h:55 [inline] atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1301 [inline] queued_spin_lock include/asm-generic/qspinlock.h:111 [inline] do_raw_spin_lock+0x12b/0x2f0 kernel/locking/spinlock_debug.c:116 __run_hrtimer kernel/time/hrtimer.c:2036 [inline] __hrtimer_run_queues+0x466/0xa10 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x3a/0xb0 kernel/rcu/tree.c:752 Code: e8 db 23 25 0a 89 c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd d0 b7 4f 8e 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 0c ba 88 00 48 c7 c3 d8 58 6e 93 49 03 1e 48 89 RSP: 0018:ffffc9000d5df290 EFLAGS: 00000246 RAX: 1ffffffff1c9f6fb RBX: 0000000000000001 RCX: 0000000080000002 RDX: 0000000000000000 RSI: ffffffff8c4bdc60 RDI: ffffffff8c4bdc20 RBP: ffffffff82404734 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59d20 R12: 0000000000000002 R13: ffffffff8eb59c60 R14: ffffffff8e4fb7d8 R15: dffffc0000000000 trace_lock_acquire include/trace/events/lock.h:23 [inline] lock_acquire+0x5f/0x350 kernel/locking/lockdep.c:5831 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] page_table_check_clear+0x141/0x500 mm/page_table_check.c:77 ptep_get_and_clear_full arch/x86/include/asm/jump_label.h:-1 [inline] get_and_clear_full_ptes include/linux/pgtable.h:879 [inline] zap_present_folio_ptes mm/memory.c:1648 [inline] zap_present_ptes mm/memory.c:1730 [inline] do_zap_pte_range mm/memory.c:1832 [inline] zap_pte_range mm/memory.c:1934 [inline] zap_pmd_range mm/memory.c:2020 [inline] zap_pud_range mm/memory.c:2048 [inline] zap_p4d_range mm/memory.c:2069 [inline] __zap_vma_range+0x39bb/0x4f10 mm/memory.c:2109 unmap_vmas+0x390/0x550 mm/memory.c:2178 exit_mmap+0x293/0x9f0 mm/mmap.c:1300 __mmput+0x118/0x420 kernel/fork.c:1187 exit_mm+0x221/0x2d0 kernel/exit.c:615 do_exit+0x6cd/0x2360 kernel/exit.c:997 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152 get_signal+0x121b/0x12c0 kernel/signal.c:3046 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x104/0x730 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3f7239de99 Code: Unable to access opcode bytes at 0x7f3f7239de6f. RSP: 002b:00007f3f731df0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007f3f72625fa8 RCX: 00007f3f7239de99 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f3f72625fac RBP: 00007f3f72625fa0 R08: 3fffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3f72626038 R14: 00007ffe2e7cde40 R15: 00007ffe2e7cdf28 task:syz-executor state:R running task stack:21424 pid:20017 tgid:20017 ppid:20013 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_release+0x2d7/0x3c0 kernel/locking/lockdep.c:5893 Code: 7d ca 11 00 00 00 00 eb b5 e8 c5 fd 2d 0a f7 c3 00 02 00 00 74 b9 65 48 8b 05 b5 38 ca 11 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 85 59 6d ff cc 48 8d 3d 12 3c b8 RSP: 0018:ffffc900060574e8 EFLAGS: 00000286 RAX: 68a600d451a80f00 RBX: 0000000000000206 RCX: 0000000000000046 RDX: 0000000000000000 RSI: ffffffff8e4b28e4 RDI: ffffffff8c4bdc80 RBP: ffff888035b62aa0 R08: ffffc90006057ee0 R09: ffffc90006057618 R10: dffffc0000000000 R11: fffff52000c0aec5 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff8eb59c60 R15: ffff888035b61f00 rcu_lock_release include/linux/rcupdate.h:310 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4584 [inline] slab_alloc_node mm/slub.c:4917 [inline] kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4931 copy_signal+0x50/0x650 kernel/fork.c:1728 copy_process+0x1df3/0x4390 kernel/fork.c:2286 kernel_clone+0x2d7/0x940 kernel/fork.c:2748 __do_sys_clone kernel/fork.c:2889 [inline] __se_sys_clone kernel/fork.c:2873 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2873 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa21cfc6912 RSP: 002b:00007fffa60278c0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fffa60278c0 RCX: 00007fa21cfc6912 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007fffa6027a4c R08: 0000000000000000 R09: 0000000000000001 R10: 00005555634cc7d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 0000000000182308 R15: 00007fffa6027aa0 task:syz.5.5840 state:R running task stack:27112 pid:27894 tgid:27893 ppid:26432 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:679 RIP: 0010:mas_root lib/maple_tree.c:759 [inline] RIP: 0010:mas_start+0x103/0x550 lib/maple_tree.c:1179 Code: 43 4c 00 48 8b 44 24 28 42 80 3c 30 00 74 08 48 89 df e8 80 49 6c f6 4c 8b 23 49 83 c4 48 4c 89 e0 48 c1 e8 03 42 80 3c 30 00 <74> 08 4c 89 e7 e8 63 49 6c f6 4d 8b 24 24 e8 8a 9b 08 00 89 c5 31 RSP: 0018:ffffc9000d32f578 EFLAGS: 00000246 RAX: 1ffff1100512be69 RBX: ffffc9000d32f640 RCX: 1ffff92001a65ed1 RDX: 1ffff92001a65ec8 RSI: 0000000000000001 RDI: ffffc9000d32f668 RBP: 0000000000000001 R08: ffffffff8bca0116 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59c60 R12: ffff88802895f348 R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff92001a65ed1 mas_state_walk lib/maple_tree.c:2945 [inline] mt_find+0x231/0x630 lib/maple_tree.c:6274 find_vma+0xed/0x160 mm/mmap.c:908 lock_mm_and_find_vma+0x66/0x340 mm/mmap_lock.c:504 do_user_addr_fault+0x341/0x1340 arch/x86/mm/fault.c:1366 handle_page_fault arch/x86/mm/fault.c:1483 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 RIP: 0010:copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline] RIP: 0010:raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline] RIP: 0010:_inline_copy_from_user include/linux/uaccess.h:185 [inline] RIP: 0010:_copy_from_user+0x75/0xb0 lib/usercopy.c:18 Code: fd eb 49 48 b8 00 f0 ff ff ff 7f 00 00 49 39 c7 4c 0f 47 f8 4c 89 f7 89 de e8 f7 b7 60 fd 0f 01 cb 4c 89 f7 48 89 d9 4c 89 fe a4 0f 1f 00 49 89 cf 0f 01 ca 31 ff 48 89 ce e8 b6 25 f3 fc 4d RSP: 0018:ffffc9000d32f980 EFLAGS: 00050246 RAX: 00007ffffffff001 RBX: 0000000000000e02 RCX: 00000000000000c2 RDX: 0000000000000001 RSI: 000020000000f000 RDI: ffff88802afe6d40 RBP: 0000000000001000 R08: ffff88802afe6e01 R09: 1ffff110055fcdc0 R10: dffffc0000000000 R11: ffffed10055fcdc1 R12: 00000000000001fe R13: ffff88802afe6000 R14: ffff88802afe6000 R15: 000020000000e2c0 copy_from_user include/linux/uaccess.h:222 [inline] snd_rawmidi_kernel_write1+0x3ad/0x640 sound/core/rawmidi.c:1560 snd_rawmidi_write+0x5b6/0xbc0 sound/core/rawmidi.c:1629 do_loop_readv_writev fs/read_write.c:851 [inline] vfs_writev+0x4bb/0x990 fs/read_write.c:1060 do_writev+0x154/0x2e0 fs/read_write.c:1104 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f11db39de99 RSP: 002b:00007f11dc333028 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f11db625fa0 RCX: 00007f11db39de99 RDX: 0000000000000002 RSI: 0000200000000840 RDI: 0000000000000005 RBP: 00007f11db433eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f11db626038 R14: 00007f11db625fa0 R15: 00007ffe21e45488 rcu: rcu_preempt kthread starved for 10496 jiffies! g244097 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:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64 Code: dc 7e 02 e9 fe 5f 3f 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 53 8e 18 00 fb f4 d7 5f 3f f5 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffffff8e807de0 EFLAGS: 00000242 RAX: 00000000015cbd01 RBX: ffffffff819b433c RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8e22d06b RDI: ffffffff8c4bdc80 RBP: ffffffff8e807eb8 R08: ffff8880b86338db R09: 1ffff110170c671b R10: dffffc0000000000 R11: ffffed10170c671c R12: 0000000000000000 R13: 1ffffffff1d11de8 R14: 1ffffffff1d00fc4 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888124f4e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f57b521f90c CR3: 0000000077ec7000 CR4: 0000000000350ef0 Call Trace: arch_safe_halt arch/x86/kernel/process.c:767 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:768 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x1cc/0x540 kernel/sched/idle.c:355 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454 rest_init+0x2de/0x300 init/main.c:717 start_kernel+0x392/0x3e0 init/main.c:1175 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x137/0x1b0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x157