================================ WARNING: inconsistent lock state 5.16.0-rc4-next-20211210-syzkaller #0 Not tainted -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. udevd/2971 [HC0[0]:SC1[7]:HE1:SE0] takes: ffffffff8bca9b40 (fs_reclaim){+.?.}-{0:0}, at: might_alloc include/linux/sched/mm.h:253 [inline] ffffffff8bca9b40 (fs_reclaim){+.?.}-{0:0}, at: slab_pre_alloc_hook mm/slab.h:739 [inline] ffffffff8bca9b40 (fs_reclaim){+.?.}-{0:0}, at: slab_alloc_node mm/slub.c:3145 [inline] ffffffff8bca9b40 (fs_reclaim){+.?.}-{0:0}, at: slab_alloc mm/slub.c:3239 [inline] ffffffff8bca9b40 (fs_reclaim){+.?.}-{0:0}, at: kmem_cache_alloc_trace+0x3b/0x2c0 mm/slub.c:3256 {SOFTIRQ-ON-W} state was registered at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __fs_reclaim_acquire mm/page_alloc.c:4550 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4564 might_alloc include/linux/sched/mm.h:253 [inline] slab_pre_alloc_hook mm/slab.h:739 [inline] slab_alloc_node mm/slub.c:3145 [inline] slab_alloc mm/slub.c:3239 [inline] kmem_cache_alloc_trace+0x3b/0x2c0 mm/slub.c:3256 kmalloc include/linux/slab.h:581 [inline] kzalloc include/linux/slab.h:715 [inline] alloc_workqueue_attrs+0x38/0x80 kernel/workqueue.c:3405 wq_numa_init kernel/workqueue.c:5972 [inline] workqueue_init+0x12f/0x9e3 kernel/workqueue.c:6099 kernel_init_freeable+0x3fb/0x73a init/main.c:1602 kernel_init+0x1a/0x1d0 init/main.c:1507 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 irq event stamp: 6934110 hardirqs last enabled at (6934110): [] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline] hardirqs last enabled at (6934110): [] _raw_spin_unlock_irqrestore+0x50/0x70 kernel/locking/spinlock.c:194 hardirqs last disabled at (6934109): [] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] hardirqs last disabled at (6934109): [] _raw_spin_lock_irqsave+0x4e/0x50 kernel/locking/spinlock.c:162 softirqs last enabled at (6933238): [] invoke_softirq kernel/softirq.c:432 [inline] softirqs last enabled at (6933238): [] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 softirqs last disabled at (6933641): [] invoke_softirq kernel/softirq.c:432 [inline] softirqs last disabled at (6933641): [] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(fs_reclaim); lock(fs_reclaim); *** DEADLOCK *** 8 locks held by udevd/2971: #0: ffffc90000dc0d70 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline] #0: ffffc90000dc0d70 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1411 #1: ffffffff8bb818a0 (rcu_read_lock){....}-{1:2}, at: ip6_nd_hdr net/ipv6/ndisc.c:466 [inline] #1: ffffffff8bb818a0 (rcu_read_lock){....}-{1:2}, at: ndisc_send_skb+0x84b/0x17f0 net/ipv6/ndisc.c:502 #2: ffffffff8bb81840 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #2: ffffffff8bb81840 (rcu_read_lock_bh){....}-{1:2}, at: ip6_finish_output2+0x2ad/0x14f0 net/ipv6/ip6_output.c:112 #3: ffffffff8bb81840 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1e3/0x3640 net/core/dev.c:4036 #4: ffffffff8bb818a0 (rcu_read_lock){....}-{1:2}, at: geneve_xmit+0xde/0x3530 drivers/net/geneve.c:1068 #5: ffffffff8bb818a0 (rcu_read_lock){....}-{1:2}, at: ip6_route_output_flags+0x0/0x320 net/ipv6/route.c:778 #6: ffffffff8bb818a0 (rcu_read_lock){....}-{1:2}, at: ip6_pol_route+0x156/0x11e0 net/ipv6/route.c:2217 #7: ffffffff8bb81840 (rcu_read_lock_bh){....}-{1:2}, at: rt6_probe net/ipv6/route.c:632 [inline] #7: ffffffff8bb81840 (rcu_read_lock_bh){....}-{1:2}, at: find_match.part.0+0x35a/0xd00 net/ipv6/route.c:752 stack backtrace: CPU: 1 PID: 2971 Comm: udevd Not tainted 5.16.0-rc4-next-20211210-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+0xcd/0x134 lib/dump_stack.c:106 print_usage_bug kernel/locking/lockdep.c:203 [inline] valid_state kernel/locking/lockdep.c:3945 [inline] mark_lock_irq kernel/locking/lockdep.c:4148 [inline] mark_lock.cold+0x61/0x8e kernel/locking/lockdep.c:4605 mark_usage kernel/locking/lockdep.c:4500 [inline] __lock_acquire+0x11d5/0x54a0 kernel/locking/lockdep.c:4981 lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __fs_reclaim_acquire mm/page_alloc.c:4550 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4564 might_alloc include/linux/sched/mm.h:253 [inline] slab_pre_alloc_hook mm/slab.h:739 [inline] slab_alloc_node mm/slub.c:3145 [inline] slab_alloc mm/slub.c:3239 [inline] kmem_cache_alloc_trace+0x3b/0x2c0 mm/slub.c:3256 kmalloc include/linux/slab.h:581 [inline] kzalloc include/linux/slab.h:715 [inline] ref_tracker_alloc+0xe1/0x430 lib/ref_tracker.c:74 netdev_tracker_alloc include/linux/netdevice.h:3860 [inline] dev_hold_track include/linux/netdevice.h:3877 [inline] rt6_probe net/ipv6/route.c:661 [inline] find_match.part.0+0xac9/0xd00 net/ipv6/route.c:752 find_match net/ipv6/route.c:825 [inline] __find_rr_leaf+0x17f/0xd20 net/ipv6/route.c:826 find_rr_leaf net/ipv6/route.c:847 [inline] rt6_select net/ipv6/route.c:891 [inline] fib6_table_lookup+0x649/0xa20 net/ipv6/route.c:2185 ip6_pol_route+0x1c5/0x11e0 net/ipv6/route.c:2221 pol_lookup_func include/net/ip6_fib.h:580 [inline] fib6_rule_lookup+0x52a/0x6f0 net/ipv6/fib6_rules.c:120 ip6_route_output_flags_noref+0x2e2/0x380 net/ipv6/route.c:2629 ip6_route_output_flags+0x72/0x320 net/ipv6/route.c:2642 ip6_route_output include/net/ip6_route.h:98 [inline] ip6_dst_lookup_tail+0x5ab/0x1620 net/ipv6/ip6_output.c:1070 ip6_dst_lookup_flow+0x8c/0x1d0 net/ipv6/ip6_output.c:1200 geneve_get_v6_dst+0x46f/0x9a0 drivers/net/geneve.c:858 geneve6_xmit_skb drivers/net/geneve.c:991 [inline] geneve_xmit+0x520/0x3530 drivers/net/geneve.c:1074 __netdev_start_xmit include/linux/netdevice.h:4685 [inline] netdev_start_xmit include/linux/netdevice.h:4699 [inline] xmit_one net/core/dev.c:3473 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3489 __dev_queue_xmit+0x2983/0x3640 net/core/dev.c:4112 neigh_resolve_output net/core/neighbour.c:1522 [inline] neigh_resolve_output+0x50e/0x820 net/core/neighbour.c:1502 neigh_output include/net/neighbour.h:541 [inline] ip6_finish_output2+0x56e/0x14f0 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x61e/0xe80 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:451 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ndisc_send_skb+0xa99/0x17f0 net/ipv6/ndisc.c:508 ndisc_send_rs+0x12e/0x6f0 net/ipv6/ndisc.c:702 addrconf_rs_timer+0x3f2/0x820 net/ipv6/addrconf.c:3898 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x675/0xa20 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:55 [inline] RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:342 [inline] RIP: 0010:deref_stack_reg+0x56/0x150 arch/x86/kernel/unwind_orc.c:352 Code: 3c 03 0f 8e d7 00 00 00 41 8b 04 24 85 c0 74 62 49 8d 7c 24 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 c3 00 00 00 49 8d 7c 24 10 4d 8b 6c 24 08 48 b8 00 00 00 00 RSP: 0018:ffffc90001f3f770 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffffc90001f3f908 RCX: 0000000000000000 RDX: 1ffff920003e7f1a RSI: ffffc90001f3f898 RDI: ffffc90001f3f8d0 RBP: ffffc90001f3f898 R08: ffffffff8e0d9036 R09: 0000000000000001 R10: fffff520003e7f24 R11: 000000000008808a R12: ffffc90001f3f8c8 R13: ffffc90001f3f8fd R14: ffffc90001f3f8c8 R15: ffffc90001f3f8fc unwind_next_frame+0x13f9/0x1ce0 arch/x86/kernel/unwind_orc.c:600 __unwind_start+0x51b/0x800 arch/x86/kernel/unwind_orc.c:712 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0x5c/0xe0 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:436 [inline] __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 kasan_slab_alloc include/linux/kasan.h:260 [inline] slab_post_alloc_hook mm/slab.h:766 [inline] slab_alloc_node mm/slub.c:3231 [inline] slab_alloc mm/slub.c:3239 [inline] kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3244 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138 getname_flags+0x9a/0xe0 include/linux/audit.h:323 user_path_at_empty+0x2b/0x60 fs/namei.c:2850 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0x142/0x390 fs/stat.c:221 vfs_fstatat fs/stat.c:243 [inline] __do_sys_newfstatat+0x96/0x120 fs/stat.c:412 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fb1661771da Code: 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 0b 00 00 00 66 2e 0f 1f 84 00 00 00 00 00 90 41 89 ca b8 06 01 00 00 0f 05 <3d> 00 f0 ff ff 77 07 31 c0 c3 0f 1f 40 00 48 8b 15 69 fc 0c 00 f7 RSP: 002b:00007fff17c701b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 000055e3ccb82aa0 RCX: 00007fb1661771da RDX: 00007fff17c701c0 RSI: 00007fb16620d75a RDI: 000000000000000d RBP: 000000000000000d R08: 0000000000090800 R09: 000055e3ccb81cb0 R10: 0000000000001000 R11: 0000000000000202 R12: 00007fff17c701c0 R13: 00000000000000ff R14: 00007fff17c702b0 R15: 0000000000000000 BUG: sleeping function called from invalid context at include/linux/sched/mm.h:256 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2971, name: udevd preempt_count: 701, expected: 0 RCU nest depth: 4, expected: 0 INFO: lockdep is turned off. Preemption disabled at: [] unwind_next_frame+0x120/0x1ce0 arch/x86/kernel/unwind_orc.c:428 CPU: 1 PID: 2971 Comm: udevd Not tainted 5.16.0-rc4-next-20211210-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+0xcd/0x134 lib/dump_stack.c:106 __might_resched.cold+0x222/0x26b kernel/sched/core.c:9583 might_alloc include/linux/sched/mm.h:256 [inline] slab_pre_alloc_hook mm/slab.h:739 [inline] slab_alloc_node mm/slub.c:3145 [inline] slab_alloc mm/slub.c:3239 [inline] kmem_cache_alloc_trace+0x25d/0x2c0 mm/slub.c:3256 kmalloc include/linux/slab.h:581 [inline] kzalloc include/linux/slab.h:715 [inline] ref_tracker_alloc+0xe1/0x430 lib/ref_tracker.c:74 netdev_tracker_alloc include/linux/netdevice.h:3860 [inline] dev_hold_track include/linux/netdevice.h:3877 [inline] rt6_probe net/ipv6/route.c:661 [inline] find_match.part.0+0xac9/0xd00 net/ipv6/route.c:752 find_match net/ipv6/route.c:825 [inline] __find_rr_leaf+0x17f/0xd20 net/ipv6/route.c:826 find_rr_leaf net/ipv6/route.c:847 [inline] rt6_select net/ipv6/route.c:891 [inline] fib6_table_lookup+0x649/0xa20 net/ipv6/route.c:2185 ip6_pol_route+0x1c5/0x11e0 net/ipv6/route.c:2221 pol_lookup_func include/net/ip6_fib.h:580 [inline] fib6_rule_lookup+0x52a/0x6f0 net/ipv6/fib6_rules.c:120 ip6_route_output_flags_noref+0x2e2/0x380 net/ipv6/route.c:2629 ip6_route_output_flags+0x72/0x320 net/ipv6/route.c:2642 ip6_route_output include/net/ip6_route.h:98 [inline] ip6_dst_lookup_tail+0x5ab/0x1620 net/ipv6/ip6_output.c:1070 ip6_dst_lookup_flow+0x8c/0x1d0 net/ipv6/ip6_output.c:1200 geneve_get_v6_dst+0x46f/0x9a0 drivers/net/geneve.c:858 geneve6_xmit_skb drivers/net/geneve.c:991 [inline] geneve_xmit+0x520/0x3530 drivers/net/geneve.c:1074 __netdev_start_xmit include/linux/netdevice.h:4685 [inline] netdev_start_xmit include/linux/netdevice.h:4699 [inline] xmit_one net/core/dev.c:3473 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3489 __dev_queue_xmit+0x2983/0x3640 net/core/dev.c:4112 neigh_resolve_output net/core/neighbour.c:1522 [inline] neigh_resolve_output+0x50e/0x820 net/core/neighbour.c:1502 neigh_output include/net/neighbour.h:541 [inline] ip6_finish_output2+0x56e/0x14f0 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x61e/0xe80 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:451 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ndisc_send_skb+0xa99/0x17f0 net/ipv6/ndisc.c:508 ndisc_send_rs+0x12e/0x6f0 net/ipv6/ndisc.c:702 addrconf_rs_timer+0x3f2/0x820 net/ipv6/addrconf.c:3898 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x675/0xa20 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:55 [inline] RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:342 [inline] RIP: 0010:deref_stack_reg+0x56/0x150 arch/x86/kernel/unwind_orc.c:352 Code: 3c 03 0f 8e d7 00 00 00 41 8b 04 24 85 c0 74 62 49 8d 7c 24 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 c3 00 00 00 49 8d 7c 24 10 4d 8b 6c 24 08 48 b8 00 00 00 00 RSP: 0018:ffffc90001f3f770 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffffc90001f3f908 RCX: 0000000000000000 RDX: 1ffff920003e7f1a RSI: ffffc90001f3f898 RDI: ffffc90001f3f8d0 RBP: ffffc90001f3f898 R08: ffffffff8e0d9036 R09: 0000000000000001 R10: fffff520003e7f24 R11: 000000000008808a R12: ffffc90001f3f8c8 R13: ffffc90001f3f8fd R14: ffffc90001f3f8c8 R15: ffffc90001f3f8fc unwind_next_frame+0x13f9/0x1ce0 arch/x86/kernel/unwind_orc.c:600 __unwind_start+0x51b/0x800 arch/x86/kernel/unwind_orc.c:712 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0x5c/0xe0 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:436 [inline] __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 kasan_slab_alloc include/linux/kasan.h:260 [inline] slab_post_alloc_hook mm/slab.h:766 [inline] slab_alloc_node mm/slub.c:3231 [inline] slab_alloc mm/slub.c:3239 [inline] kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3244 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138 getname_flags+0x9a/0xe0 include/linux/audit.h:323 user_path_at_empty+0x2b/0x60 fs/namei.c:2850 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0x142/0x390 fs/stat.c:221 vfs_fstatat fs/stat.c:243 [inline] __do_sys_newfstatat+0x96/0x120 fs/stat.c:412 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fb1661771da Code: 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 0b 00 00 00 66 2e 0f 1f 84 00 00 00 00 00 90 41 89 ca b8 06 01 00 00 0f 05 <3d> 00 f0 ff ff 77 07 31 c0 c3 0f 1f 40 00 48 8b 15 69 fc 0c 00 f7 RSP: 002b:00007fff17c701b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 000055e3ccb82aa0 RCX: 00007fb1661771da RDX: 00007fff17c701c0 RSI: 00007fb16620d75a RDI: 000000000000000d RBP: 000000000000000d R08: 0000000000090800 R09: 000055e3ccb81cb0 R10: 0000000000001000 R11: 0000000000000202 R12: 00007fff17c701c0 R13: 00000000000000ff R14: 00007fff17c702b0 R15: 0000000000000000 ---------------- Code disassembly (best guess): 0: 3c 03 cmp $0x3,%al 2: 0f 8e d7 00 00 00 jle 0xdf 8: 41 8b 04 24 mov (%r12),%eax c: 85 c0 test %eax,%eax e: 74 62 je 0x72 10: 49 8d 7c 24 08 lea 0x8(%r12),%rdi 15: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 1c: fc ff df 1f: 48 89 fa mov %rdi,%rdx 22: 48 c1 ea 03 shr $0x3,%rdx 26: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) * 2a: 0f 85 c3 00 00 00 jne 0xf3 <-- trapping instruction 30: 49 8d 7c 24 10 lea 0x10(%r12),%rdi 35: 4d 8b 6c 24 08 mov 0x8(%r12),%r13 3a: 48 rex.W 3b: b8 00 00 00 00 mov $0x0,%eax