rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): (detected by 0, t=10502 jiffies, g=115941, q=17) rcu: All QSes seen, last rcu_preempt kthread activity 10481 (4295020981-4295010500), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10481 jiffies! g115941 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:24888 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4681 [inline] __schedule+0xc07/0x11f0 kernel/sched/core.c:5938 schedule+0x14b/0x210 kernel/sched/core.c:6017 schedule_timeout+0x1aa/0x2f0 kernel/time/timer.c:1881 rcu_gp_fqs_loop kernel/rcu/tree.c:1996 [inline] rcu_gp_kthread+0x10fd/0x1720 kernel/rcu/tree.c:2169 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 32399 Comm: syz-executor.5 Not tainted 5.14.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:105 nmi_cpu_backtrace+0x16c/0x190 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x191/0x2f0 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation+0x200/0x270 kernel/rcu/tree_stall.h:479 print_other_cpu_stall kernel/rcu/tree_stall.h:584 [inline] check_cpu_stall kernel/rcu/tree_stall.h:709 [inline] rcu_pending kernel/rcu/tree.c:3922 [inline] rcu_sched_clock_irq+0x2297/0x2a30 kernel/rcu/tree.c:2641 update_process_times+0x197/0x200 kernel/time/timer.c:1785 tick_sched_handle kernel/time/tick-sched.c:226 [inline] tick_sched_timer+0x27d/0x420 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1537 [inline] __hrtimer_run_queues+0x4cb/0xa60 kernel/time/hrtimer.c:1601 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1663 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline] __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1106 sysvec_apic_timer_interrupt+0x3e/0xb0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:196 Code: 00 00 00 0f 1f 00 be 0d 00 00 00 48 c7 c7 60 4a 75 8c e8 7f 42 49 00 c3 cc cc cc cc cc cc cc cc cc cc cc cc cc cc 48 8b 04 24 <65> 48 8b 0c 25 c0 ef 01 00 65 8b 15 e4 b7 81 7e f7 c2 00 01 ff 00 RSP: 0018:ffffc90000007b28 EFLAGS: 00000283 RAX: ffffffff8828e648 RBX: ffff8880653a2ad0 RCX: ffff888028788000 RDX: 0000000000000102 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00000000000002fe R08: ffffffff88284ebf R09: 0000000000000003 R10: fffff52000000f55 R11: 0000000000000004 R12: ffff8880653a2b24 R13: dffffc0000000000 R14: ffff88806bfb4ef4 R15: 0000000000014ef4 fq_pie_timer+0x168/0x280 net/sched/sch_fq_pie.c:382 call_timer_fn+0xf6/0x210 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers+0x703/0x8f0 kernel/time/timer.c:1734 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1747 __do_softirq+0x372/0x783 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x21b/0x260 kernel/softirq.c:636 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:434 [inline] RIP: 0010:__pv_queued_spin_lock_slowpath+0x662/0xcb0 kernel/locking/qspinlock.c:508 Code: 45 00 00 48 8b 44 24 10 8a 04 10 84 c0 0f 85 57 01 00 00 48 8b 44 24 08 c6 00 01 41 bc 00 80 ff ff eb 0c 0f 1f 44 00 00 f3 90 <41> ff c4 74 69 41 0f b6 04 17 84 c0 75 35 80 3b 00 75 eb 48 89 df RSP: 0018:ffffc900027fecc0 EFLAGS: 00000202 RAX: 0000000000000000 RBX: ffff88802a63c180 RCX: 1ffff110054c7830 RDX: dffffc0000000000 RSI: 0000000000000002 RDI: ffff88802a63c182 RBP: ffffc900027fedb0 R08: dffffc0000000000 R09: ffffed10054c7831 R10: ffffed10054c7831 R11: 0000000000000000 R12: 00000000ffff815c R13: ffff8880b9c52354 R14: 1ffff11017380001 R15: 1ffff110054c7830 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x4c9/0x8e0 kernel/locking/spinlock_debug.c:113 spin_lock include/linux/spinlock.h:354 [inline] ext4_lock_group fs/ext4/ext4.h:3456 [inline] ext4_mb_regular_allocator+0x230d/0x45b0 fs/ext4/mballoc.c:2740 ext4_mb_new_blocks+0xc4b/0x2470 fs/ext4/mballoc.c:5515 ext4_ext_map_blocks+0x2be3/0x7210 fs/ext4/extents.c:4245 ext4_map_blocks+0xab3/0x1cb0 fs/ext4/inode.c:638 ext4_alloc_file_blocks+0x3ce/0xd10 fs/ext4/extents.c:4432 ext4_zero_range fs/ext4/extents.c:4544 [inline] ext4_fallocate+0x11e8/0x35c0 fs/ext4/extents.c:4681 vfs_fallocate+0x556/0x8b0 fs/open.c:311 file_ioctl fs/ioctl.c:497 [inline] do_vfs_ioctl+0x2245/0x2ab0 fs/ioctl.c:1048 __do_sys_ioctl fs/ioctl.c:1067 [inline] __se_sys_ioctl+0x83/0x170 fs/ioctl.c:1055 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665e9 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb8ee3a1188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 RDX: 0000000020000040 RSI: 0000000040305839 RDI: 0000000000000005 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffc5b10b51f R14: 00007fb8ee3a1300 R15: 0000000000022000 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 00 00 add %al,(%rax) 2: 0f 1f 00 nopl (%rax) 5: be 0d 00 00 00 mov $0xd,%esi a: 48 c7 c7 60 4a 75 8c mov $0xffffffff8c754a60,%rdi 11: e8 7f 42 49 00 callq 0x494295 16: c3 retq 17: cc int3 18: cc int3 19: cc int3 1a: cc int3 1b: cc int3 1c: cc int3 1d: cc int3 1e: cc int3 1f: cc int3 20: cc int3 21: cc int3 22: cc int3 23: cc int3 24: cc int3 25: 48 8b 04 24 mov (%rsp),%rax * 29: 65 48 8b 0c 25 c0 ef mov %gs:0x1efc0,%rcx <-- trapping instruction 30: 01 00 32: 65 8b 15 e4 b7 81 7e mov %gs:0x7e81b7e4(%rip),%edx # 0x7e81b81d 39: f7 c2 00 01 ff 00 test $0xff0100,%edx