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BUG: KCSAN: data-race in ctx_sched_out / perf_mmap

write to 0xffff88815b4692b8 of 8 bytes by task 2540 on cpu 1:
 update_context_time kernel/events/core.c:1532 [inline]
 ctx_sched_out+0x1cf/0x410 kernel/events/core.c:3272
 task_ctx_sched_out kernel/events/core.c:2687 [inline]
 perf_event_context_sched_out kernel/events/core.c:3494 [inline]
 __perf_event_task_sched_out+0x64c/0xec0 kernel/events/core.c:3597
 perf_event_task_sched_out include/linux/perf_event.h:1231 [inline]
 prepare_task_switch+0x134/0x140 kernel/sched/core.c:4744
 context_switch kernel/sched/core.c:4892 [inline]
 __schedule+0x382/0x680 kernel/sched/core.c:6287
 schedule+0x67/0x90 kernel/sched/core.c:6366
 freezable_schedule include/linux/freezer.h:172 [inline]
 futex_wait_queue_me+0x162/0x210 kernel/futex.c:2853
 futex_wait+0x153/0x440 kernel/futex.c:2954
 do_futex+0x9ee/0x2050 kernel/futex.c:3964
 __do_sys_futex kernel/futex.c:4041 [inline]
 __se_sys_futex+0xea/0x3a0 kernel/futex.c:4022
 __x64_sys_futex+0x74/0x80 kernel/futex.c:4022
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88815b4692b8 of 8 bytes by task 2539 on cpu 0:
 perf_event_time kernel/events/core.c:1543 [inline]
 perf_event_update_time kernel/events/core.c:645 [inline]
 perf_mmap+0xa6b/0xe70 kernel/events/core.c:6351
 call_mmap include/linux/fs.h:2168 [inline]
 mmap_region+0xb1a/0x1260 mm/mmap.c:1787
 do_mmap+0x781/0xc20 mm/mmap.c:1575
 vm_mmap_pgoff+0x117/0x1f0 mm/util.c:519
 ksys_mmap_pgoff+0x284/0x350 mm/mmap.c:1624
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000000000000691c -> 0x000000000000983f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2539 Comm: syz-executor.5 Not tainted 5.15.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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