rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P25535/1:b..l P25533/1:b..l rcu: (detected by 1, t=10502 jiffies, g=97549, q=207 ncpus=2) task:syz.2.3985 state:R running task stack:26024 pid:25533 tgid:25532 ppid:5843 task_flags:0x400140 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288 irqentry_exit+0x36/0x90 kernel/entry/common.c:197 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_release+0x183/0x2f0 kernel/locking/lockdep.c:5893 Code: 0f c1 05 38 3e 3e 12 83 f8 01 0f 85 1d 01 00 00 9c 58 f6 c4 02 0f 85 08 01 00 00 41 f7 c5 00 02 00 00 74 01 fb 48 8b 44 24 10 <65> 48 2b 05 4d fc 3d 12 0f 85 58 01 00 00 48 83 c4 18 5b 41 5c 41 RSP: 0018:ffffc90003d56c60 EFLAGS: 00000206 RAX: 0b381b73fef22d00 RBX: ffffffff8e5c1160 RCX: ffffc90003d56c6c RDX: 0000000000000001 RSI: ffffffff8de293c0 RDI: ffffffff8c161100 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 00000000000061ed R12: ffffffff816ae8a4 R13: 0000000000000202 R14: ffff88803fc04880 R15: 0000000000000002 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0x3f9/0x20a0 arch/x86/kernel/unwind_orc.c:479 __unwind_start+0x45f/0x7f0 arch/x86/kernel/unwind_orc.c:758 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0x73/0x100 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 save_stack+0x160/0x1f0 mm/page_owner.c:156 __set_page_owner+0x91/0x550 mm/page_owner.c:329 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798 __do_fault+0x10d/0x490 mm/memory.c:5152 do_read_fault mm/memory.c:5573 [inline] do_fault mm/memory.c:5707 [inline] do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234 handle_pte_fault mm/memory.c:6052 [inline] __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195 handle_mm_fault+0x589/0xd10 mm/memory.c:6364 faultin_page mm/gup.c:1144 [inline] __get_user_pages+0x551/0x34a0 mm/gup.c:1446 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880 __mm_populate+0x1d8/0x380 mm/gup.c:1983 mm_populate include/linux/mm.h:3367 [inline] vm_mmap_pgoff+0x37f/0x470 mm/util.c:585 ksys_mmap_pgoff+0x7d/0x5c0 mm/mmap.c:604 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fad6738ebe9 RSP: 002b:00007fad6824d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007fad675b5fa0 RCX: 00007fad6738ebe9 RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007fad67411e19 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fad675b6038 R14: 00007fad675b5fa0 R15: 00007ffeea956df8 task:syz.1.3984 state:R running task stack:26360 pid:25535 tgid:25527 ppid:5844 task_flags:0x400140 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288 irqentry_exit+0x36/0x90 kernel/entry/common.c:197 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:60 [inline] RIP: 0010:stack_access_ok+0x7e/0x200 arch/x86/kernel/unwind_orc.c:393 Code: 85 52 01 00 00 48 89 da 48 8b 4b 10 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e 0b 01 00 00 <8b> 13 85 d2 74 23 49 39 ef 77 1e 48 39 e9 76 19 4a 8d 54 25 00 49 RSP: 0018:ffffc90003cd6c68 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffc90003cd6d68 RCX: ffffc90003cd8000 RDX: 1ffff9200079adad RSI: ffffc90003cd6e00 RDI: ffffc90003cd6d68 RBP: ffffc90003cd6e00 R08: ffffffff913f7dea R09: 0000000000000000 R10: 0000000000000001 R11: 00000000000061ed R12: 0000000000000008 R13: ffffc90003cd6d78 R14: ffffc90003cd6d70 R15: ffffc90003cd0000 deref_stack_reg arch/x86/kernel/unwind_orc.c:403 [inline] unwind_next_frame+0xcfe/0x20a0 arch/x86/kernel/unwind_orc.c:585 __unwind_start+0x45f/0x7f0 arch/x86/kernel/unwind_orc.c:758 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0x73/0x100 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 save_stack+0x160/0x1f0 mm/page_owner.c:156 __set_page_owner+0x91/0x550 mm/page_owner.c:329 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798 __do_fault+0x10d/0x490 mm/memory.c:5152 do_read_fault mm/memory.c:5573 [inline] do_fault mm/memory.c:5707 [inline] do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234 handle_pte_fault mm/memory.c:6052 [inline] __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195 handle_mm_fault+0x589/0xd10 mm/memory.c:6364 faultin_page mm/gup.c:1144 [inline] __get_user_pages+0x551/0x34a0 mm/gup.c:1446 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880 __mm_populate+0x1d8/0x380 mm/gup.c:1983 mm_populate include/linux/mm.h:3367 [inline] vm_mmap_pgoff+0x37f/0x470 mm/util.c:585 ksys_mmap_pgoff+0x7d/0x5c0 mm/mmap.c:604 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fec7c18ebe9 RSP: 002b:00007fec7cf25038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007fec7c3b6090 RCX: 00007fec7c18ebe9 RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007fec7c211e19 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fec7c3b6128 R14: 00007fec7c3b6090 R15: 00007ffe243412e8 rcu: rcu_preempt kthread starved for 10569 jiffies! g97549 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:27784 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 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 Not tainted 6.16.0-syzkaller-11952-g6e64f4580381 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: 3c 63 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 f3 62 17 00 fb f4 4c 0d 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c2 RAX: 0000000009b30e05 RBX: 0000000000000000 RCX: ffffffff8b92ac29 RDX: 0000000000000000 RSI: ffffffff8de4e7b1 RDI: ffffffff8c161100 RBP: fffffbfff1c52ef8 R08: 0000000000000001 R09: ffffed1017086655 R10: ffff8880b84332ab R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff8e2977c0 R14: ffffffff90aaff90 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881246c4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f336ad4d137 CR3: 000000007ab1c000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:757 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428 rest_init+0x16b/0x2b0 init/main.c:744 start_kernel+0x3ee/0x4d0 init/main.c:1097 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x148