rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (0 ticks this GP) idle=c6bc/1/0x4000000000000000 softirq=21083/21083 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5203/1:b..l rcu: (detected by 1, t=10502 jiffies, g=14217, q=180 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6981 Comm: syz.1.271 Not tainted 6.15.0-rc1-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:write_comp_data kernel/kcov.c:246 [inline] RIP: 0010:__sanitizer_cov_trace_cmp8+0x11/0x90 kernel/kcov.c:294 Code: 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 f3 0f 1e fa 4c 8b 04 24 65 48 8b 0c 25 08 70 65 93 <65> 8b 05 58 29 a2 11 25 00 01 ff 00 74 10 3d 00 01 00 00 75 57 83 RSP: 0018:ffffc90000007c68 EFLAGS: 00000046 RAX: 1ffff11006ab3428 RBX: ffff88803559b550 RCX: ffff888033611e00 RDX: 0000000000010000 RSI: 0000000000000000 RDI: 183e53834c000000 RBP: 0000000000000000 R08: ffffffff8a1ecf00 R09: fffff52000000f7c R10: dffffc0000000000 R11: fffff52000000f7c R12: 0000000000000002 R13: 183e53834c000000 R14: ffff88802991e330 R15: ffff88803559b400 FS: 00007f33bc1b86c0(0000) GS:ffff888124fc9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe953984f98 CR3: 0000000078986000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: advance_sched+0x2a0/0xca0 net/sched/sch_taprio.c:941 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x5a6/0xd40 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x403/0xa40 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x110/0x420 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0x167/0x2f0 arch/x86/include/asm/irqflags.h:-1 Code: c7 44 24 10 00 00 00 00 9c 8f 44 24 10 f7 44 24 10 00 02 00 00 0f 85 fd 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 65 48 8b 45 00 <48> 3b 44 24 38 0f 85 72 01 00 00 48 83 c4 40 5b 41 5c 41 5d 41 5e RSP: 0018:ffffc90003aae768 EFLAGS: 00000206 RAX: ebcd0f388a34e700 RBX: ffffffff8ed3dfe0 RCX: ebcd0f388a34e700 RDX: 0000000000000000 RSI: ffffffff8e4ea087 RDI: ffffffff8ca0e1e0 RBP: ffffffff93657020 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000246 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xd5/0x23b0 arch/x86/kernel/unwind_orc.c:479 __unwind_start+0x59a/0x740 arch/x86/kernel/unwind_orc.c:758 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0xe7/0x150 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x11a/0x1d0 kernel/stacktrace.c:122 save_stack+0xfc/0x1f0 mm/page_owner.c:156 __reset_page_owner+0x76/0x1e0 mm/page_owner.c:308 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1262 [inline] free_unref_folios+0xdfd/0x17e0 mm/page_alloc.c:2737 folios_put_refs+0x70a/0x800 mm/swap.c:992 folios_put include/linux/mm.h:1622 [inline] folio_batch_move_lru+0x3ae/0x430 mm/swap.c:175 __folio_batch_add_and_move+0x5ce/0xdb0 mm/swap.c:196 shmem_alloc_and_add_folio+0xdc3/0x1070 mm/shmem.c:1952 shmem_get_folio_gfp+0x655/0x1800 mm/shmem.c:2533 shmem_fault+0x223/0x5c0 mm/shmem.c:2734 __do_fault+0x135/0x390 mm/memory.c:5098 do_read_fault mm/memory.c:5518 [inline] do_fault mm/memory.c:5652 [inline] do_pte_missing mm/memory.c:4160 [inline] handle_pte_fault+0x3f0c/0x61c0 mm/memory.c:5997 __handle_mm_fault mm/memory.c:6140 [inline] handle_mm_fault+0x1030/0x1aa0 mm/memory.c:6309 faultin_page mm/gup.c:1193 [inline] __get_user_pages+0x1adc/0x4180 mm/gup.c:1491 populate_vma_page_range+0x266/0x340 mm/gup.c:1929 __mm_populate+0x27d/0x460 mm/gup.c:2032 mm_populate include/linux/mm.h:3470 [inline] vm_mmap_pgoff+0x390/0x530 mm/util.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f33bb38d169 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f33bc1b8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f33bb5a5fa0 RCX: 00007f33bb38d169 RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007f33bb40e2a0 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f33bb5a5fa0 R15: 00007ffeec7bbb88 task:udevd state:R running task stack:23176 pid:5203 tgid:5203 ppid:1 task_flags:0x400140 flags:0x00000002 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x1b33/0x51f0 kernel/sched/core.c:6767 preempt_schedule_notrace+0x103/0x140 kernel/sched/core.c:7040 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13 rcu_is_watching+0x7e/0xb0 kernel/rcu/tree.c:737 trace_lock_acquire include/trace/events/lock.h:24 [inline] lock_acquire+0x5e/0x2f0 kernel/locking/lockdep.c:5829 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xd5/0x23b0 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11e/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x11a/0x1d0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:319 [inline] __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4151 [inline] slab_alloc_node mm/slub.c:4200 [inline] kmem_cache_alloc_noprof+0x1e1/0x390 mm/slub.c:4207 alloc_empty_file+0x56/0x1d0 fs/file_table.c:234 path_openat+0x10d/0x35d0 fs/namei.c:3990 do_filp_open+0x284/0x4e0 fs/namei.c:4031 do_sys_openat2+0x12b/0x1d0 fs/open.c:1429 do_sys_open fs/open.c:1444 [inline] __do_sys_openat fs/open.c:1460 [inline] __se_sys_openat fs/open.c:1455 [inline] __x64_sys_openat+0x249/0x2a0 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe4fed169a4 RSP: 002b:00007ffee72cf200 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00005624353b51af RCX: 00007fe4fed169a4 RDX: 0000000000080141 RSI: 00005624353b50d8 RDI: 00000000ffffff9c RBP: 00005624353b50d8 R08: 00000000ffffffff R09: 0000000000000000 R10: 00000000000001a4 R11: 0000000000000246 R12: 0000000000080141 R13: ffffffffffffffff R14: 00000000ffffffff R15: 00000000ffffffff rcu: rcu_preempt kthread starved for 10502 jiffies! g14217 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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:26952 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x1b33/0x51f0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x163/0x360 kernel/sched/core.c:6860 schedule_timeout+0x15b/0x2b0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x2e1/0x1340 kernel/rcu/tree.c:2046 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2248 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 6987 Comm: syz.2.272 Not tainted 6.15.0-rc1-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:__sanitizer_cov_trace_pc+0x46/0x70 kernel/kcov.c:222 Code: ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 3c 16 00 00 00 74 2c 8b 91 18 16 00 00 83 fa 02 75 21 48 8b 91 20 16 00 00 48 8b 32 <48> 8d 7e 01 8b 89 1c 16 00 00 48 39 cf 73 08 48 89 3a 48 89 44 f2 RSP: 0018:ffffc90003437978 EFLAGS: 00000246 RAX: ffffffff81b7661d RBX: 1ffff110170c8219 RCX: ffff888062861e00 RDX: ffffc9000c479000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc90003437b80 R08: ffffffff81b765e8 R09: 1ffffffff20bd6ce R10: dffffc0000000000 R11: fffffbfff20bd6cf R12: ffff8880b873ab88 R13: ffff8880b86410c8 R14: ffff8880b873ab80 R15: 0000000000000000 FS: 00007f483fa046c0(0000) GS:ffff8881250c9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c32624c CR3: 000000002d554000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: csd_lock_wait kernel/smp.c:340 [inline] smp_call_function_many_cond+0x1bcd/0x2d40 kernel/smp.c:885 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2455 [inline] text_poke_bp_batch+0x354/0xb30 arch/x86/kernel/alternative.c:2665 text_poke_flush arch/x86/kernel/alternative.c:2856 [inline] text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2863 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_slow_inc_cpuslocked+0x80/0xf0 kernel/jump_label.c:168 static_key_slow_inc+0x1a/0x30 kernel/jump_label.c:191 io_uring_create+0x1da/0xc90 io_uring/io_uring.c:3689 io_uring_setup io_uring/io_uring.c:3828 [inline] __do_sys_io_uring_setup io_uring/io_uring.c:3862 [inline] __se_sys_io_uring_setup+0x2e8/0x360 io_uring/io_uring.c:3853 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f483eb8d169 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f483fa04038 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9 RAX: ffffffffffffffda RBX: 00007f483eda5fa0 RCX: 00007f483eb8d169 RDX: 0000000000000000 RSI: 0000200000000200 RDI: 000000000000410d RBP: 00007f483ec0e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f483eda5fa0 R15: 00007ffdc7670728