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BUG: KCSAN: data-race in ktime_get_real_seconds / timekeeping_advance

write to 0xffffffff86041b08 of 280 bytes by interrupt on cpu 0:
 timekeeping_advance+0x88e/0xd80 include/linux/string.h:378
 update_wall_time+0x19/0x20 kernel/time/timekeeping.c:2137
 tick_do_update_jiffies64+0x1a4/0x250 kernel/time/tick-sched.c:94
 tick_sched_do_timer+0xd4/0xe0 kernel/time/tick-sched.c:138
 tick_sched_timer+0x43/0xe0 kernel/time/tick-sched.c:1292
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x274/0x5f0 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1638
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0xdc/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 is_atomic kernel/kcsan/core.c:143 [inline]
 should_watch kernel/kcsan/core.c:162 [inline]
 check_access kernel/kcsan/core.c:408 [inline]
 __tsan_read8+0xc7/0x1f0 kernel/kcsan/core.c:530
 find_entry.isra.0+0x43/0x130 fs/proc/proc_sysctl.c:123
 find_subdir+0x4f/0xe0 fs/proc/proc_sysctl.c:956
 get_subdir fs/proc/proc_sysctl.c:1024 [inline]
 __register_sysctl_table+0x7e5/0x880 fs/proc/proc_sysctl.c:1360
 register_net_sysctl+0x32/0x50 net/sysctl_net.c:121
 mpls_dev_sysctl_register+0x119/0x1a0 net/mpls/af_mpls.c:1422
 mpls_add_dev net/mpls/af_mpls.c:1473 [inline]
 mpls_dev_notify+0x1d3/0x540 net/mpls/af_mpls.c:1599
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:95
 __raw_notifier_call_chain kernel/notifier.c:396 [inline]
 raw_notifier_call_chain+0x37/0x50 kernel/notifier.c:403
 call_netdevice_notifiers_info+0x48/0xc0 net/core/dev.c:1668
 call_netdevice_notifiers_extack net/core/dev.c:1680 [inline]
 call_netdevice_notifiers net/core/dev.c:1694 [inline]
 register_netdevice+0x7a5/0xa50 net/core/dev.c:9115
 __ip_tunnel_create+0x214/0x400 net/ipv4/ip_tunnel.c:269
 ip_tunnel_init_net+0x24d/0x3d1 net/ipv4/ip_tunnel.c:1060
 vti_init_net+0x57/0x160 net/ipv4/ip_vti.c:463
 ops_init+0x8c/0x240 net/core/net_namespace.c:137
 setup_net+0x191/0x4b0 net/core/net_namespace.c:335
 copy_net_ns+0x1e3/0x390 net/core/net_namespace.c:476
 create_new_namespaces+0x2e2/0x4b0 kernel/nsproxy.c:103
 unshare_nsproxy_namespaces+0xb9/0x170 kernel/nsproxy.c:202
 ksys_unshare+0x2dc/0x710 kernel/fork.c:2827
 __do_sys_unshare kernel/fork.c:2895 [inline]
 __se_sys_unshare kernel/fork.c:2893 [inline]
 __x64_sys_unshare+0x28/0x40 kernel/fork.c:2893
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff86041b78 of 8 bytes by task 11948 on cpu 1:
 ktime_get_real_seconds+0x20/0x40 kernel/time/timekeeping.c:127
 recently_deleted fs/ext4/ialloc.c:699 [inline]
 find_inode_bit.isra.0+0x1e2/0x300 fs/ext4/ialloc.c:722
 __ext4_new_inode+0xd10/0x2ec0 fs/ext4/ialloc.c:914
 ext4_symlink+0x30e/0x970 fs/ext4/namei.c:3262
 vfs_symlink fs/namei.c:4119 [inline]
 vfs_symlink+0x218/0x310 fs/namei.c:4105
 do_symlinkat+0x1a5/0x1e0 fs/namei.c:4146
 __do_sys_symlink fs/namei.c:4165 [inline]
 __se_sys_symlink fs/namei.c:4163 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4163
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11948 Comm: syz-executor.1 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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