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BUG: KCSAN: data-race in arch_perf_update_userpage / perf_mmap

read to 0xffff8881079a5028 of 8 bytes by task 3107 on cpu 0:
 arch_perf_update_userpage+0x48/0x1f0 arch/x86/events/core.c:2725
 perf_event_update_userpage+0x33c/0x3b0 kernel/events/core.c:5960
 cpu_clock_event_add+0x11d/0x130 kernel/events/core.c:10796
 event_sched_in+0x781/0xe60 kernel/events/core.c:2601
 group_sched_in kernel/events/core.c:2637 [inline]
 merge_sched_in kernel/events/core.c:3818 [inline]
 visit_groups_merge+0x943/0x1a50 kernel/events/core.c:3762
 ctx_flexible_sched_in kernel/events/core.c:3860 [inline]
 ctx_sched_in+0x221/0x240 kernel/events/core.c:3908
 perf_event_sched_in kernel/events/core.c:2741 [inline]
 perf_event_context_sched_in kernel/events/core.c:3959 [inline]
 __perf_event_task_sched_in+0x37c/0x8d0 kernel/events/core.c:4002
 perf_event_task_sched_in include/linux/perf_event.h:1213 [inline]
 finish_task_switch+0x1ef/0x280 kernel/sched/core.c:4870
 context_switch kernel/sched/core.c:4998 [inline]
 __schedule+0x43a/0x690 kernel/sched/core.c:6304
 preempt_schedule_common kernel/sched/core.c:6470 [inline]
 __cond_resched+0x3f/0x90 kernel/sched/core.c:8183
 might_resched include/linux/kernel.h:110 [inline]
 might_alloc include/linux/sched/mm.h:256 [inline]
 slab_pre_alloc_hook mm/slab.h:705 [inline]
 slab_alloc mm/slab.c:3298 [inline]
 kmem_cache_alloc+0x45/0x320 mm/slab.c:3499
 getname_flags+0x84/0x3f0 fs/namei.c:138
 getname+0x15/0x20 fs/namei.c:217
 do_sys_openat2+0x6d/0x2b0 fs/open.c:1208
 do_sys_open fs/open.c:1230 [inline]
 __do_sys_openat fs/open.c:1246 [inline]
 __se_sys_openat fs/open.c:1241 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1241
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff8881079a5028 of 8 bytes by task 3110 on cpu 1:
 perf_event_init_userpage kernel/events/core.c:5900 [inline]
 perf_mmap+0xcba/0xeb0 kernel/events/core.c:6434
 call_mmap include/linux/fs.h:2079 [inline]
 mmap_region+0xb04/0x10b0 mm/mmap.c:1793
 do_mmap+0x781/0xc20 mm/mmap.c:1582
 vm_mmap_pgoff+0x117/0x1f0 mm/util.c:519
 ksys_mmap_pgoff+0x265/0x320 mm/mmap.c:1630
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000000 -> 0x0000000000000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3110 Comm: syz-executor.2 Tainted: G        W         5.17.0-rc7-syzkaller-00241-gf0e18b03fcaf-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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