[moderation] [mm?] KCSAN: data-race in copy_mm / vms_complete_munmap_vmas

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bc9ff192a6c9 Merge tag 'net-6.16-rc6' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1294ba8c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a2f5ccd29a82f8aa
dashboard link: https://syzkaller.appspot.com/bug?extid=c47560027f2749bc292d
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [Liam.H...@oracle.com ak...@linux-foundation.org ja...@google.com linux-...@vger.kernel.org linu...@kvack.org lorenzo...@oracle.com pfal...@suse.de vba...@suse.cz]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cd81278ad98c/disk-bc9ff192.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1fea20ae9800/vmlinux-bc9ff192.xz
kernel image: https://storage.googleapis.com/syzbot-assets/00054e9f79c3/bzImage-bc9ff192.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c47560...@syzkaller.appspotmail.com

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

read-write to 0xffff88810005b230 of 4 bytes by task 9906 on cpu 0:
vms_complete_munmap_vmas+0x55/0x440 mm/vma.c:1264
__mmap_complete mm/vma.c:2519 [inline]
__mmap_region mm/vma.c:2630 [inline]
mmap_region+0x1167/0x1580 mm/vma.c:2692
do_mmap+0x9b3/0xbe0 mm/mmap.c:561
vm_mmap_pgoff+0x17a/0x2e0 mm/util.c:579
ksys_mmap_pgoff+0xc2/0x310 mm/mmap.c:607
x64_sys_call+0x1602/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:10
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810005b180 of 1344 bytes by task 9908 on cpu 1:
dup_mm kernel/fork.c:1471 [inline]
copy_mm+0xe2/0x370 kernel/fork.c:1529
copy_process+0xcf1/0x1f90 kernel/fork.c:2169
kernel_clone+0x16c/0x5b0 kernel/fork.c:2599
__do_sys_clone kernel/fork.c:2742 [inline]
__se_sys_clone kernel/fork.c:2726 [inline]
__x64_sys_clone+0xe6/0x120 kernel/fork.c:2726
x64_sys_call+0x2c59/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:57
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9908 Comm: syz.3.1762 Not tainted 6.16.0-rc5-syzkaller-00121-gbc9ff192a6c9 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

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