[moderation] [mm?] KCSAN: data-race in copy_mm / vma_complete (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 02dc699f83d0 Merge tag 'kbuild-fixes-7.2-1' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=133d74c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=a2ca6b1b404353a6c33a
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [ak...@linux-foundation.org ja...@google.com li...@infradead.org linux-...@vger.kernel.org linu...@kvack.org l...@kernel.org pfal...@suse.de vba...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/497e59955483/disk-02dc699f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7db9613be7ce/vmlinux-02dc699f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8fb12c248b4/bzImage-02dc699f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a2ca6b...@syzkaller.appspotmail.com

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

read-write to 0xffff888117f7a4c8 of 4 bytes by task 22296 on cpu 1:
vma_complete+0x3e1/0x850 mm/vma.c:360
__split_vma+0x592/0x640 mm/vma.c:569
split_vma mm/vma.c:599 [inline]
vma_modify+0xb29/0xc80 mm/vma.c:1691
vma_modify_flags+0x182/0x210 mm/vma.c:1719
mprotect_fixup+0x3a2/0x680 mm/mprotect.c:789
do_mprotect_pkey+0x69e/0x950 mm/mprotect.c:967
__do_sys_mprotect mm/mprotect.c:988 [inline]
__se_sys_mprotect mm/mprotect.c:985 [inline]
__x64_sys_mprotect+0x48/0x60 mm/mprotect.c:985
x64_sys_call+0x2768/0x3020 arch/x86/include/generated/asm/syscalls_64.h:11
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 0xffff888117f7a300 of 1728 bytes by task 22305 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: 22305 Comm: syz.0.2981 Tainted: G W syzkaller #0 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================


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