rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=6464/1/0x4000000000000000 softirq=53435/53436 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P11108/1:b..l rcu: (detected by 1, t=10506 jiffies, g=42941, q=495 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 11091 Comm: syz.6.1374 Not tainted 6.15.0-rc7-next-20250526-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:__sanitizer_cov_trace_pc+0x5d/0x70 kernel/kcov.c:235 Code: 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 08 cc cc cc cc cc 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 RSP: 0018:ffffc90000007d38 EFLAGS: 00000006 RAX: ffffffff81ae5f04 RBX: ffff8880b8627c08 RCX: ffff888011a9da00 RDX: 0000000000010000 RSI: 1ffff110170c4f7a RDI: ffff88807a8a3340 RBP: ffffc90000007e90 R08: ffff88807a8a3357 R09: 0000000000000000 R10: ffff88807a8a3340 R11: ffffed100f51466b R12: ffff88807a8a3340 R13: dffffc0000000000 R14: ffff8880b8627c18 R15: ffff8880b8627bc0 FS: 00007f81d1ff66c0(0000) GS:ffff888125c56000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7024d18310 CR3: 000000003393e000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __run_hrtimer kernel/time/hrtimer.c:1789 [inline] __hrtimer_run_queues+0x6b4/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:80 [inline] RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:102 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:227 [inline] RIP: 0010:unwind_next_frame+0x130e/0x2390 arch/x86/kernel/unwind_orc.c:494 Code: c1 e8 3f 48 01 c8 48 83 e0 fe 4c 8d 3c 45 00 00 00 00 49 01 ef 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 <84> c0 75 27 49 63 07 4c 01 f8 49 8d 4f 04 4c 39 e0 48 0f 46 e9 49 RSP: 0018:ffffc90003337038 EFLAGS: 00000a06 RAX: 0000000000000000 RBX: ffffffff8fbc1d6c RCX: dffffc0000000000 RDX: ffffffff8fbc1d34 RSI: ffffffff903b1004 RDI: ffffffff8be292a0 RBP: ffffffff8fbc1d34 R08: 000000000000000f R09: ffffffff81728a45 R10: ffffc90003337158 R11: ffffffff81ace330 R12: ffffffff8201ef47 R13: ffffffff8fbc1d34 R14: ffffc90003337108 R15: ffffffff8fbc1d50 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 save_stack+0xf7/0x1f0 mm/page_owner.c:156 __set_page_owner+0x8d/0x4a0 mm/page_owner.c:329 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704 prep_new_page mm/page_alloc.c:1712 [inline] get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2438 shmem_alloc_folio mm/shmem.c:1851 [inline] shmem_alloc_and_add_folio+0x447/0xf60 mm/shmem.c:1890 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2532 shmem_get_folio mm/shmem.c:2638 [inline] shmem_write_begin+0xf7/0x2b0 mm/shmem.c:3288 generic_perform_write+0x2c4/0x910 mm/filemap.c:4103 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3463 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x54b/0xa90 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f81d418d41f Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48 RSP: 002b:00007f81d1ff5df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007f81d418d41f RDX: 0000000001000000 RSI: 00007f81c9a00000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000004449 R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000003 R13: 00007f81d1ff5ef0 R14: 00007f81d1ff5eb0 R15: 00007f81c9a00000 task:syz.0.1382 state:R running task stack:26888 pid:11108 tgid:11107 ppid:5832 task_flags:0x40044c flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5392 [inline] __schedule+0x16f5/0x4d00 kernel/sched/core.c:6781 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6961 preempt_schedule+0xae/0xc0 kernel/sched/core.c:6985 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] zap_pte_range mm/memory.c:1763 [inline] zap_pmd_range mm/memory.c:1825 [inline] zap_pud_range mm/memory.c:1854 [inline] zap_p4d_range mm/memory.c:1875 [inline] unmap_page_range+0x38e5/0x4580 mm/memory.c:1896 unmap_single_vma mm/memory.c:1939 [inline] unmap_vmas+0x399/0x580 mm/memory.c:1983 exit_mmap+0x248/0xb50 mm/mmap.c:1284 __mmput+0x118/0x420 kernel/fork.c:1121 exit_mm+0x1da/0x2c0 kernel/exit.c:581 do_exit+0x640/0x22e0 kernel/exit.c:943 do_group_exit+0x21c/0x2d0 kernel/exit.c:1104 get_signal+0x125e/0x1310 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fcd7ad8e969 RSP: 002b:00007fcd7bb740e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007fcd7afb5fa8 RCX: 00007fcd7ad8e969 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fcd7afb5fa8 RBP: 00007fcd7afb5fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcd7afb5fac R13: 0000000000000000 R14: 00007ffd1eedd600 R15: 00007ffd1eedd6e8 rcu: rcu_preempt kthread starved for 10506 jiffies! g42941 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:27320 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5392 [inline] __schedule+0x16f5/0x4d00 kernel/sched/core.c:6781 __schedule_loop kernel/sched/core.c:6859 [inline] schedule+0x165/0x360 kernel/sched/core.c:6874 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 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: CPU: 1 UID: 0 PID: 11109 Comm: syz.2.1381 Not tainted 6.15.0-rc7-next-20250526-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0xf72/0x12d0 kernel/smp.c:885 Code: 01 31 ff e8 60 78 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 0b 74 0b 00 eb 37 f3 90 43 0f b6 04 2c 84 c0 75 10 <41> f7 07 01 00 00 00 74 1e e8 f0 73 0b 00 eb e5 44 89 f9 80 e1 07 RSP: 0018:ffffc900033f75a0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff8880b873cb00 RCX: ffff888026013c00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900033f7700 R08: ffffffff8fa12ef7 R09: 1ffffffff1f425de R10: dffffc0000000000 R11: fffffbfff1f425df R12: 1ffff110170c86ad R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880b8643568 FS: 0000000000000000(0000) GS:ffff888125d56000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b3071eff8 CR3: 000000000df38000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 __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+0x6b1/0x12c0 arch/x86/mm/tlb.c:1451 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:496 free_ldt_pgtables+0x17b/0x320 arch/x86/kernel/ldt.c:411 arch_exit_mmap arch/x86/include/asm/mmu_context.h:234 [inline] exit_mmap+0x17c/0xb50 mm/mmap.c:1270 __mmput+0x118/0x420 kernel/fork.c:1121 exit_mm+0x1da/0x2c0 kernel/exit.c:581 do_exit+0x640/0x22e0 kernel/exit.c:943 do_group_exit+0x21c/0x2d0 kernel/exit.c:1104 __do_sys_exit_group kernel/exit.c:1115 [inline] __se_sys_exit_group kernel/exit.c:1113 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1113 x64_sys_call+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7024d8e969 Code: Unable to access opcode bytes at 0x7f7024d8e93f. RSP: 002b:00007fff4b0ca278 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7024d8e969 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fff4b0ca2dc R08: 000000054b0ca36f R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000118 R13: 00000000000927c0 R14: 000000000004d9e5 R15: 00007fff4b0ca330