[moderation] [kernel?] KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d2da77f431ac Merge tag 'parisc-for-6.7-rc3' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=119cbe0ce80000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c1151391aefc0c3
dashboard link: https://syzkaller.appspot.com/bug?extid=1bdaa74c416fdc11d7ad
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [b...@alien8.de dave....@linux.intel.com h...@zytor.com linux-...@vger.kernel.org mi...@redhat.com tg...@linutronix.de x...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0ebc29947781/disk-d2da77f4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a82ec858fbee/vmlinux-d2da77f4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d45f2fa85085/bzImage-d2da77f4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1bdaa7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn

read-write to 0xffffffff86efc31c of 4 bytes by task 3187 on cpu 0:
pcpu_update_empty_pages mm/percpu.c:602 [inline]
pcpu_chunk_populated mm/percpu.c:1531 [inline]
pcpu_balance_populated mm/percpu.c:2088 [inline]
pcpu_balance_workfn+0x94c/0xa50 mm/percpu.c:2238
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

read to 0xffffffff86efc31c of 4 bytes by task 3747 on cpu 1:
pcpu_alloc+0x9bc/0x10b0 mm/percpu.c:1868
__alloc_percpu_gfp+0x26/0x30 mm/percpu.c:1930
bpf_map_alloc_percpu+0xaa/0x200 kernel/bpf/syscall.c:467
prealloc_init+0x19f/0x470 kernel/bpf/hashtab.c:337
htab_map_alloc+0x715/0x9e0 kernel/bpf/hashtab.c:568
map_create+0x713/0xa40 kernel/bpf/syscall.c:1210
__sys_bpf+0x62a/0x780 kernel/bpf/syscall.c:5365
__do_sys_bpf kernel/bpf/syscall.c:5487 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5485 [inline]
__x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5485
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000001 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3747 Comm: syz-executor.4 Not tainted 6.7.0-rc2-syzkaller-00265-gd2da77f431ac #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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[syzbot]

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