rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...0: (1 GPs behind) idle=3e6/1/0x4000000000000000 softirq=198316/198318 fqs=3006 (detected by 1, t=10502 jiffies, g=446345, q=806) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 20022 Comm: syz-executor.2 Not tainted 5.8.0-rc5-next-20200716-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:check_memory_region+0x16/0x180 mm/kasan/generic.c:191 Code: 02 0f 1f 00 48 89 f2 be f8 00 00 00 e9 13 87 00 02 0f 1f 00 48 85 f6 0f 84 70 01 00 00 49 89 f9 41 54 44 0f b6 c2 49 01 f1 55 <53> 0f 82 18 01 00 00 48 b8 ff ff ff ff ff 7f ff ff 48 39 c7 0f 86 RSP: 0018:ffffc90000007cc8 EFLAGS: 00000082 RAX: 0000000000000000 RBX: 1ffff92000000f9d RCX: ffffffff815b3c21 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff88804e0b2ae8 RBP: ffff88804e0b2ae8 R08: 0000000000000001 R09: ffff88804e0b2aec R10: fffffbfff18ca96d R11: 0000000000000000 R12: ffff88804e0b2af0 R13: ffff88804e0b2af8 R14: ffff88804e0b2b40 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055b1ba834c68 CR3: 000000004e080000 CR4: 00000000001526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: instrument_atomic_write include/linux/instrumented.h:71 [inline] atomic_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:705 [inline] queued_spin_lock include/asm-generic/qspinlock.h:78 [inline] do_raw_spin_lock+0x111/0x2b0 kernel/locking/spinlock_debug.c:113 spin_lock include/linux/spinlock.h:354 [inline] advance_sched+0x4f/0x990 net/sched/sch_taprio.c:699 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0x6a9/0xfc0 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1079 [inline] __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1096 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] sysvec_apic_timer_interrupt+0xe0/0x120 arch/x86/kernel/apic/apic.c:1090 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:587 RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:196 Code: 48 89 ef 5d e9 31 33 3f 00 5d be 03 00 00 00 e9 e6 6b 25 02 66 0f 1f 44 00 00 48 8b be b0 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 <65> 48 8b 14 25 c0 fe 01 00 65 8b 05 90 ce 8d 7e a9 00 01 ff 00 48 RSP: 0018:ffffc9000868f6d0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffea00016fe3c0 RCX: ffffffff81accd11 RDX: 0000000000000000 RSI: ffff88804bbac500 RDI: 0000000000000007 RBP: ffffea00016fe3c0 R08: 0000000000000000 R09: ffffea00016fe387 R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00016fe3c0 R13: ffffea00016fe3c8 R14: 0000000000000000 R15: dead000000000100 PageSwapBacked include/linux/page-flags.h:351 [inline] PageSwapCache include/linux/page-flags.h:396 [inline] free_swap_cache+0xff/0x300 mm/swap_state.c:266 free_pages_and_swap_cache+0x58/0x90 mm/swap_state.c:294 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline] tlb_flush_mmu_free mm/mmu_gather.c:242 [inline] tlb_flush_mmu+0xe9/0x6b0 mm/mmu_gather.c:249 zap_pte_range mm/memory.c:1157 [inline] zap_pmd_range mm/memory.c:1195 [inline] zap_pud_range mm/memory.c:1224 [inline] zap_p4d_range mm/memory.c:1245 [inline] unmap_page_range+0x1e22/0x2b20 mm/memory.c:1266 unmap_single_vma+0x198/0x300 mm/memory.c:1311 unmap_vmas+0x16f/0x2f0 mm/memory.c:1343 exit_mmap+0x2b1/0x530 mm/mmap.c:3187 __mmput+0x122/0x470 kernel/fork.c:1075 mmput+0x53/0x60 kernel/fork.c:1096 exit_mm kernel/exit.c:483 [inline] do_exit+0xa8b/0x29f0 kernel/exit.c:793 do_group_exit+0x125/0x310 kernel/exit.c:903 get_signal+0x40b/0x1ee0 kernel/signal.c:2743 do_signal+0x82/0x2520 arch/x86/kernel/signal.c:810 exit_to_usermode_loop arch/x86/entry/common.c:235 [inline] __prepare_exit_to_usermode+0x14d/0x1f0 arch/x86/entry/common.c:269 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:393 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c1d9 Code: Bad RIP value. RSP: 002b:00007f8610d95cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000078bf08 RCX: 000000000045c1d9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000078bf08 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c R13: 00007ffd3101cf5f R14: 00007f8610d969c0 R15: 000000000078bf0c rcu: rcu_preempt kthread starved for 4431 jiffies! g446345 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: rcu_preempt R running task 29120 10 2 0x00004000 Call Trace: context_switch kernel/sched/core.c:3445 [inline] __schedule+0x8b4/0x1e80 kernel/sched/core.c:4169 schedule+0xd0/0x2a0 kernel/sched/core.c:4244 schedule_timeout+0x148/0x250 kernel/time/timer.c:1897 rcu_gp_fqs_loop kernel/rcu/tree.c:1871 [inline] rcu_gp_kthread+0xae5/0x1b50 kernel/rcu/tree.c:2041 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294