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BUG: KCSAN: data-race in __acct_update_integrals / vm_stat_account

read to 0xffff8880b7ab5640 of 8 bytes by interrupt on cpu 0:
 __acct_update_integrals+0x1b1/0x1e0 kernel/tsacct.c:137
 acct_account_cputime+0x4e/0x60 kernel/tsacct.c:161
 account_system_index_time+0xa2/0xb0 kernel/sched/cputime.c:175
 irqtime_account_process_tick.isra.0+0x16a/0x1b0 kernel/sched/cputime.c:389
 account_process_tick+0x14e/0x190 kernel/sched/cputime.c:484
 update_process_times+0x29/0x80 kernel/time/timer.c:1724
 tick_sched_handle+0x75/0x100 kernel/time/tick-sched.c:167
 tick_sched_timer+0x58/0xe0 kernel/time/tick-sched.c:1299
 __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
 decode_watchpoint kernel/kcsan/encoding.h:65 [inline]
 find_watchpoint kernel/kcsan/core.c:98 [inline]
 check_access kernel/kcsan/core.c:453 [inline]
 __tsan_read8+0x3a/0x100 kernel/kcsan/core.c:596
 __rb_insert lib/rbtree.c:163 [inline]
 rb_insert_color+0x29d/0x350 lib/rbtree.c:436
 insert_entry fs/proc/proc_sysctl.c:175 [inline]
 insert_header+0x312/0x820 fs/proc/proc_sysctl.c:237
 __register_sysctl_table+0x538/0x880 fs/proc/proc_sysctl.c:1366
 register_net_sysctl+0x32/0x50 net/sysctl_net.c:121
 ipv4_sysctl_init_net+0xca/0x220 net/ipv4/sysctl_net_ipv4.c:1346
 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:2858
 __do_sys_unshare kernel/fork.c:2926 [inline]
 __se_sys_unshare kernel/fork.c:2924 [inline]
 __x64_sys_unshare+0x28/0x40 kernel/fork.c:2924
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880b7ab5640 of 8 bytes by task 9752 on cpu 1:
 vm_stat_account+0x45/0x150 mm/mmap.c:3324
 mprotect_fixup+0x311/0x510 mm/mprotect.c:439
 do_mprotect_pkey+0x3eb/0x660 mm/mprotect.c:553
 __do_sys_mprotect mm/mprotect.c:578 [inline]
 __se_sys_mprotect mm/mprotect.c:575 [inline]
 __x64_sys_mprotect+0x51/0x70 mm/mprotect.c:575
 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: 9752 Comm: syz-executor.0 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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