rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=fbe/1/0x4000000000000000 softirq=34301/34303 fqs=2 (detected by 1, t=10502 jiffies, g=54589, q=89) ============================================ WARNING: possible recursive locking detected 5.10.0-rc5-next-20201130-syzkaller #0 Not tainted -------------------------------------------- syz-executor.5/17843 is trying to acquire lock: ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: rcu_dump_cpu_stacks+0xaf/0x295 kernel/rcu/tree_stall.h:337 but task is already holding lock: ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:546 [inline] ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3784 [inline] ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0x2b6/0x11be kernel/rcu/tree.c:2593 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(rcu_node_0); lock(rcu_node_0); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by syz-executor.5/17843: #0: ffffffff8b441d08 (vmap_purge_lock){+.+.}-{3:3}, at: _vm_unmap_aliases.part.0+0x368/0x4e0 mm/vmalloc.c:1782 #1: ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:546 [inline] #1: ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] #1: ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3784 [inline] #1: ffffffff8b342958 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0x2b6/0x11be kernel/rcu/tree.c:2593 stack backtrace: CPU: 1 PID: 17843 Comm: syz-executor.5 Not tainted 5.10.0-rc5-next-20201130-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 print_deadlock_bug kernel/locking/lockdep.c:2761 [inline] check_deadlock kernel/locking/lockdep.c:2804 [inline] validate_chain kernel/locking/lockdep.c:3595 [inline] __lock_acquire.cold+0x15e/0x3b0 kernel/locking/lockdep.c:4832 lock_acquire kernel/locking/lockdep.c:5437 [inline] lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159 rcu_dump_cpu_stacks+0xaf/0x295 kernel/rcu/tree_stall.h:337 print_other_cpu_stall kernel/rcu/tree_stall.h:564 [inline] check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] rcu_pending kernel/rcu/tree.c:3784 [inline] rcu_sched_clock_irq.cold+0x7c0/0x11be kernel/rcu/tree.c:2593 update_process_times+0x16d/0x200 kernel/time/timer.c:1782 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:206 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1356 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1ce/0xea0 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1102 asm_call_irq_on_stack+0xf/0x20 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xbd/0x100 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:__sanitizer_cov_trace_pc+0x4c/0x60 kernel/kcov.c:202 Code: 0e 85 c9 74 35 8b 82 b4 14 00 00 85 c0 74 2b 8b 82 90 14 00 00 83 f8 02 75 20 48 8b 8a 98 14 00 00 8b 92 94 14 00 00 48 8b 01 <48> 83 c0 01 48 39 c2 76 07 48 89 34 c1 48 89 01 c3 0f 1f 00 41 55 RSP: 0018:ffffc90003847538 EFLAGS: 00000246 RAX: 000000000003ffff RBX: 1ffff92000708eac RCX: ffffc90013e5c000 RDX: 0000000000040000 RSI: ffffffff81657dfe RDI: 0000000000000003 RBP: ffffc90003847608 R08: 0000000000000000 R09: ffffffff8ebd2767 R10: ffffffff81657e13 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000008 rep_nop arch/x86/include/asm/vdso/processor.h:13 [inline] cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] csd_lock_wait kernel/smp.c:227 [inline] smp_call_function_single+0x1ae/0x4b0 kernel/smp.c:512 smp_call_function_many_cond+0x25f/0x9d0 kernel/smp.c:648 smp_call_function_many kernel/smp.c:711 [inline] smp_call_function kernel/smp.c:733 [inline] on_each_cpu+0x4f/0x110 kernel/smp.c:832 __purge_vmap_area_lazy+0x1f6/0x1c50 mm/vmalloc.c:1360 _vm_unmap_aliases.part.0+0x3d6/0x4e0 mm/vmalloc.c:1784 _vm_unmap_aliases mm/vmalloc.c:1758 [inline] vm_unmap_aliases+0x42/0x50 mm/vmalloc.c:1807 change_page_attr_set_clr+0x241/0x500 arch/x86/mm/pat/set_memory.c:1732 change_page_attr_clear arch/x86/mm/pat/set_memory.c:1789 [inline] set_memory_ro+0x78/0xa0 arch/x86/mm/pat/set_memory.c:1935 bpf_jit_binary_lock_ro include/linux/filter.h:824 [inline] bpf_int_jit_compile+0xdfa/0x11b0 arch/x86/net/bpf_jit_comp.c:2093 bpf_prog_select_runtime+0x5c5/0xb30 kernel/bpf/core.c:1817 bpf_prog_load+0xe6a/0x1b60 kernel/bpf/syscall.c:2215 __do_sys_bpf+0x14bb/0x4f40 kernel/bpf/syscall.c:4386 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45deb9 Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f38315d0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 0000000000001d80 RCX: 000000000045deb9 RDX: 0000000000000070 RSI: 0000000020000180 RDI: 0000000000000005 RBP: 000000000118bf60 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c R13: 00007fffe983abff R14: 00007f38315d19c0 R15: 000000000118bf2c