KCSAN: data-race in event_sched_in / perf_mmap

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ca2ef2d9f2aa Merge tag 'kcsan.2021.11.11a' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13e185d6b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=bda4b60fed516f35
dashboard link: https://syzkaller.appspot.com/bug?extid=7f6c89a9e93efa694bbe
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [ac...@kernel.org alexander...@linux.intel.com and...@kernel.org a...@kernel.org b...@vger.kernel.org dan...@iogearbox.net john.fa...@gmail.com jo...@redhat.com ka...@fb.com kps...@kernel.org linux-...@vger.kernel.org linux-pe...@vger.kernel.org mark.r...@arm.com mi...@redhat.com namh...@kernel.org net...@vger.kernel.org pet...@infradead.org songliu...@fb.com y...@fb.com]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7f6c89...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in event_sched_in / perf_mmap

write to 0xffff88813dd584d8 of 8 bytes by task 14507 on cpu 0:
perf_set_shadow_time kernel/events/core.c:2512 [inline]
perf_mmap+0xc36/0xe80 kernel/events/core.c:6352
call_mmap include/linux/fs.h:2167 [inline]
mmap_region+0xb00/0x10a0 mm/mmap.c:1786
do_mmap+0x781/0xc20 mm/mmap.c:1575
vm_mmap_pgoff+0x117/0x1f0 mm/util.c:519
ksys_mmap_pgoff+0x265/0x320 mm/mmap.c:1623
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 0xffff88813dd584d8 of 8 bytes by task 14594 on cpu 1:
perf_set_shadow_time kernel/events/core.c:2512 [inline]
event_sched_in+0x520/0xe90 kernel/events/core.c:2555
group_sched_in kernel/events/core.c:2595 [inline]
merge_sched_in kernel/events/core.c:3746 [inline]
visit_groups_merge+0x943/0x1aa0 kernel/events/core.c:3696
ctx_flexible_sched_in kernel/events/core.c:3788 [inline]
ctx_sched_in+0x1e4/0x200 kernel/events/core.c:3833
perf_event_sched_in kernel/events/core.c:2699 [inline]
perf_event_context_sched_in kernel/events/core.c:3884 [inline]
__perf_event_task_sched_in+0x37c/0x8d0 kernel/events/core.c:3927
perf_event_task_sched_in include/linux/perf_event.h:1209 [inline]
finish_task_switch+0x1ef/0x280 kernel/sched/core.c:4844
context_switch kernel/sched/core.c:4972 [inline]
__schedule+0x44a/0x6a0 kernel/sched/core.c:6250
schedule+0x81/0xb0 kernel/sched/core.c:6323
freezable_schedule include/linux/freezer.h:172 [inline]
futex_wait_queue+0xd1/0x170 kernel/futex/waitwake.c:355
futex_wait+0x126/0x350 kernel/futex/waitwake.c:656
do_futex+0x28d/0x370 kernel/futex/syscalls.c:122
__do_sys_futex kernel/futex/syscalls.c:199 [inline]
__se_sys_futex+0xe8/0x370 kernel/futex/syscalls.c:180
__x64_sys_futex+0x74/0x80 kernel/futex/syscalls.c:180
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: 0xffffffd256f9377a -> 0xffffffd256f7df95

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14594 Comm: syz-executor.2 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.