[moderation] [perf?] KCSAN: data-race in __change_pid / perf_event_switch_output (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2a8120d7b482 Merge tag 's390-6.10-2' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=140a37dc980000
kernel config: https://syzkaller.appspot.com/x/.config?x=f35bb3f898275bfc
dashboard link: https://syzkaller.appspot.com/bug?extid=b2215ca4becf45ad7e76
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ac...@kernel.org adrian...@intel.com alexander...@linux.intel.com iro...@google.com jo...@kernel.org kan....@linux.intel.com linux-...@vger.kernel.org linux-pe...@vger.kernel.org mark.r...@arm.com mi...@redhat.com namh...@kernel.org pet...@infradead.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c7fb0632f985/disk-2a8120d7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/78cc88e198bf/vmlinux-2a8120d7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/79a49ed243be/bzImage-2a8120d7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b2215c...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __change_pid / perf_event_switch_output

write to 0xffff8881296de8e8 of 8 bytes by task 6369 on cpu 1:
__change_pid+0xe9/0x1c0 kernel/pid.c:356
detach_pid+0x1c/0x30 kernel/pid.c:372
__unhash_process kernel/exit.c:129 [inline]
__exit_signal kernel/exit.c:201 [inline]
release_task+0x6c3/0xc30 kernel/exit.c:258
wait_task_zombie kernel/exit.c:1188 [inline]
wait_consider_task+0x116b/0x1670 kernel/exit.c:1415
do_wait_thread kernel/exit.c:1478 [inline]
__do_wait+0x100/0x500 kernel/exit.c:1596
do_wait+0xaf/0x270 kernel/exit.c:1630
kernel_wait4+0x164/0x1d0 kernel/exit.c:1789
__do_sys_wait4 kernel/exit.c:1817 [inline]
__se_sys_wait4 kernel/exit.c:1813 [inline]
__x64_sys_wait4+0x94/0x120 kernel/exit.c:1813
x64_sys_call+0x61d/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:62
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881296de8e8 of 8 bytes by task 12742 on cpu 0:
pid_alive include/linux/pid.h:263 [inline]
perf_event_pid_type kernel/events/core.c:1334 [inline]
perf_event_pid kernel/events/core.c:1341 [inline]
perf_event_switch_output+0x19e/0x390 kernel/events/core.c:9061
perf_iterate_sb_cpu kernel/events/core.c:8003 [inline]
perf_iterate_sb+0x34b/0x640 kernel/events/core.c:8032
perf_event_switch kernel/events/core.c:9108 [inline]
__perf_event_task_sched_in+0x789/0x7f0 kernel/events/core.c:4018
perf_event_task_sched_in include/linux/perf_event.h:1473 [inline]
finish_task_switch+0x218/0x2b0 kernel/sched/core.c:5277
context_switch kernel/sched/core.c:5411 [inline]
__schedule+0x5e8/0x940 kernel/sched/core.c:6745
__schedule_loop kernel/sched/core.c:6822 [inline]
schedule+0x55/0xc0 kernel/sched/core.c:6837
exit_to_user_mode_loop kernel/entry/common.c:102 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x9f/0x130 kernel/entry/common.c:218
do_syscall_64+0xda/0x1d0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff8881040459c0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12742 Comm: syz-executor.1 Not tainted 6.9.0-syzkaller-10713-g2a8120d7b482 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================


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[syzbot]

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