[moderation] [mm?] KCSAN: data-race in copy_mm / lru_gen_del_mm (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1229e2e57a5c Merge tag 'v7.2-rc3-smb3-server-fixes' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15217cb9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=cf98ce9dc644a63f3094
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [ak...@linux-foundation.org axelra...@google.com bao...@kernel.org da...@kernel.org han...@cmpxchg.org kas...@tencent.com linux-...@vger.kernel.org linu...@kvack.org l...@kernel.org mho...@kernel.org qi.z...@linux.dev shakee...@linux.dev wei...@google.com yua...@google.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2338c358729a/disk-1229e2e5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9518b3c3bc77/vmlinux-1229e2e5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67b0d2dd8ec6/bzImage-1229e2e5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf98ce...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in copy_mm / lru_gen_del_mm

write to 0xffff8881022f8690 of 8 bytes by task 17447 on cpu 1:
__list_del include/linux/list.h:226 [inline]
__list_del_entry include/linux/list.h:249 [inline]
list_del_init include/linux/list.h:318 [inline]
lru_gen_del_mm+0x299/0x3e0 mm/vmscan.c:2927
__mmput+0x17a/0x1c0 kernel/fork.c:1197
mmput+0x40/0x50 kernel/fork.c:1210
exit_mm+0x113/0x1a0 kernel/exit.c:615
do_exit+0x438/0x1500 kernel/exit.c:997
do_group_exit+0x138/0x140 kernel/exit.c:1152
__do_sys_exit_group kernel/exit.c:1163 [inline]
__se_sys_exit_group kernel/exit.c:1161 [inline]
__x64_sys_exit_group+0x1f/0x20 kernel/exit.c:1161
x64_sys_call+0x3008/0x3020 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881022f8000 of 1728 bytes by task 17448 on cpu 0:
dup_mm kernel/fork.c:1537 [inline]
copy_mm+0xd6/0x340 kernel/fork.c:1595
copy_process+0x108c/0x2310 kernel/fork.c:2289
kernel_clone+0x1c0/0x5f0 kernel/fork.c:2748
__do_sys_clone kernel/fork.c:2889 [inline]
__se_sys_clone kernel/fork.c:2873 [inline]
__x64_sys_clone+0x143/0x180 kernel/fork.c:2873
x64_sys_call+0x1222/0x3020 arch/x86/include/generated/asm/syscalls_64.h:57
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 17448 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup