syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=2db4/1/0x4000000000000000 softirq=87399/87400 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P49/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=87001, q=920 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 15963 Comm: syz.4.2256 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:preempt_count_add+0x42/0x1a0 kernel/sched/core.c:5832
Code: ce 99 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 f1 00 00 00 83 3d 8e d3 3e 18 00 75 07 65 8b 05 75 80 33 11 65 01 3d 6e 80 33 11 <48> c7 c0 40 d3 ce 99 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 ec 00
RSP: 0018:ffffc90000a08bc0 EFLAGS: 00000006
RAX: 0000000000010002 RBX: ffffffff99f94dd0 RCX: ffffffff99ced303
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc90000a08c78 R08: ffffc90000a08caf R09: 0000000000000000
R10: ffffc90000a08ca0 R11: fffff52000141196 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000802 R15: dffffc0000000000
FS:  00007f64520786c0(0000) GS:ffff888125ae8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6452077f98 CR3: 000000007283e000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:109 [inline]
 _raw_spin_lock_irqsave+0x8c/0xf0 kernel/locking/spinlock.c:162
 debug_object_activate+0xbb/0x420 lib/debugobjects.c:818
 debug_hrtimer_activate kernel/time/hrtimer.c:438 [inline]
 debug_activate kernel/time/hrtimer.c:477 [inline]
 enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1081
 __run_hrtimer kernel/time/hrtimer.c:1794 [inline]
 __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:kasan_check_range+0xd/0x2c0 mm/kasan/generic.c:199
Code: ff ff ff eb e1 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 55 41 57 41 56 41 55 41 54 <53> b0 01 48 85 f6 0f 84 ba 01 00 00 4c 8d 04 37 49 39 f8 0f 82 82
RSP: 0018:ffffc900050a73f0 EFLAGS: 00000246
RAX: ffffffff821171ed RBX: ffffea0001a6a000 RCX: ffffffff82117204
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffea0001a6a000
RBP: ffffea0001a6ad80 R08: ffffffff8fc3f337 R09: 1ffffffff1f87e66
R10: dffffc0000000000 R11: fffffbfff1f87e67 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffea0001a6a030 R15: 0000000000000000
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 folio_test_head include/linux/page-flags.h:847 [inline]
 folio_test_large include/linux/page-flags.h:868 [inline]
 __folio_add_rmap mm/rmap.c:1279 [inline]
 __folio_add_file_rmap mm/rmap.c:1621 [inline]
 folio_add_file_rmap_ptes+0x2f4/0xdf0 mm/rmap.c:1642
 insert_page_into_pte_locked+0x618/0x960 mm/memory.c:2313
 insert_page_in_batch_locked mm/memory.c:2348 [inline]
 insert_pages mm/memory.c:2389 [inline]
 vm_insert_pages+0x55b/0x920 mm/memory.c:2440
 io_region_mmap io_uring/memmap.c:318 [inline]
 io_uring_mmap+0x413/0x530 io_uring/memmap.c:344
 vfs_mmap include/linux/fs.h:2407 [inline]
 mmap_file mm/internal.h:167 [inline]
 __mmap_new_file_vma mm/vma.c:2413 [inline]
 __mmap_new_vma mm/vma.c:2476 [inline]
 __mmap_region mm/vma.c:2670 [inline]
 mmap_region+0x18b4/0x2110 mm/vma.c:2740
 do_mmap+0xc45/0x10d0 mm/mmap.c:558
 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:580
 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f645118ebe3
Code: f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 41 89 ca 41 f7 c1 ff 0f 00 00 75 14 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 25 c3 0f 1f 40 00 48 c7 c0 a8 ff ff ff 64 c7
RSP: 002b:00007f6452077fc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f64513d6180 RCX: 00007f645118ebe3
RDX: 0000000000000003 RSI: 0000000000040040 RDI: 0000000000000000
RBP: 0000200000000200 R08: 0000000000000009 R09: 0000000000000000
R10: 0000000000008001 R11: 0000000000000246 R12: 0000000000000009
R13: 0000200000000040 R14: 0000000000001e1e R15: 0000200000000000
 </TASK>
task:kworker/u8:3    state:R  running task     stack:19640 pid:49    tgid:49    ppid:2      task_flags:0x4208160 flags:0x00004000
Workqueue: iou_exit io_ring_exit_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7291
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:211
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:memset_orig+0x25/0xb0 arch/x86/lib/memset_64.S:64
Code: 90 90 90 90 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 01 01 48 0f af c1 41 89 f9 41 83 e1 07 75 74 48 89 d1 48 c1 e9 06 <74> 39 66 0f 1f 84 00 00 00 00 00 48 ff c9 48 89 07 48 89 47 08 48
RSP: 0018:ffffc90000b97250 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc90000b97360 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc90000b97378
RBP: dffffc0000000000 R08: ffffc90000b97387 R09: 0000000000000000
R10: ffffc90000b97378 R11: fffff52000172e71 R12: ffffc90000b976c0
R13: ffffc90000b97378 R14: ffffc90000b97328 R15: ffffc90000b97370
 unwind_next_frame+0xc98/0x2390 arch/x86/kernel/unwind_orc.c:592
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559
 __call_rcu_common kernel/rcu/tree.c:3123 [inline]
 call_rcu+0x157/0x9c0 kernel/rcu/tree.c:3243
 slab_free_hook mm/slub.c:2438 [inline]
 slab_free mm/slub.c:6181 [inline]
 kmem_cache_free+0x4b4/0x690 mm/slub.c:6292
 __io_req_caches_free+0x1c1/0x270 io_uring/io_uring.c:2826
 io_req_caches_free+0x21/0x60 io_uring/io_uring.c:2838
 io_ring_exit_work+0x415/0x930 io_uring/io_uring.c:3036
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g87001 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:27200 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7046 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7061
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5876 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xd38/0x12d0 kernel/smp.c:877
Code: 89 ee 83 e6 01 31 ff e8 16 7c 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 c1 77 0b 00 eb 38 f3 90 42 0f b6 04 2b <84> c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 a5 77 0b 00 eb e4 44
RSP: 0018:ffffc9000424f540 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 1ffff110170e7f69 RCX: ffff888027903c80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000424f6c0 R08: ffffffff8fc3f337 R09: 1ffffffff1f87e66
R10: dffffc0000000000 R11: fffffbfff1f87e67 R12: ffff8880b873fb48
R13: dffffc0000000000 R14: ffff8880b863b1c0 R15: 0000000000000001
FS:  00005555832ff500(0000) GS:ffff8881259e8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c29e072 CR3: 000000006a61e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451
 dup_mmap+0x1598/0x1ab0 mm/mmap.c:1873
 dup_mm kernel/fork.c:1504 [inline]
 copy_mm+0x13c/0x4b0 kernel/fork.c:1556
 copy_process+0x1706/0x3c00 kernel/fork.c:2196
 kernel_clone+0x21e/0x840 kernel/fork.c:2624
 __do_sys_clone kernel/fork.c:2765 [inline]
 __se_sys_clone kernel/fork.c:2749 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2749
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f541f985413
Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00
RSP: 002b:00007fff5fff89b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f541f985413
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 00005555832ff7d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 00000000000e3306 R15: 00007fff5fff8b50
 </TASK>