[moderation] [mm?] KCSAN: data-race in __se_sys_mremap / vma_complete

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c875a6c32467 Merge tag 'usb-6.19-rc3' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1358349a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b319ff1b6a2797ca
dashboard link: https://syzkaller.appspot.com/bug?extid=f76e73cc28fed0483dba
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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/6a3ff5d2bc43/disk-c875a6c3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8bfefd608d99/vmlinux-c875a6c3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9c18f1ecad19/bzImage-c875a6c3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f76e73...@syzkaller.appspotmail.com

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

read-write to 0xffff88810de45948 of 4 bytes by task 9936 on cpu 1:
vma_complete+0x13f/0x580 mm/vma.c:349
__split_vma+0x59b/0x660 mm/vma.c:561
split_vma mm/vma.c:591 [inline]
vma_modify+0xb53/0xd50 mm/vma.c:1626
vma_modify_flags+0x10c/0x190 mm/vma.c:1654
mprotect_fixup+0x30f/0x5e0 mm/mprotect.c:756
do_mprotect_pkey+0x6d6/0x980 mm/mprotect.c:930
__do_sys_mprotect mm/mprotect.c:951 [inline]
__se_sys_mprotect mm/mprotect.c:948 [inline]
__x64_sys_mprotect+0x48/0x60 mm/mprotect.c:948
x64_sys_call+0x2c3b/0x3000 arch/x86/include/generated/asm/syscalls_64.h:11
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810de45948 of 4 bytes by task 9942 on cpu 0:
check_mremap_params mm/mremap.c:1820 [inline]
do_mremap mm/mremap.c:1924 [inline]
__do_sys_mremap mm/mremap.c:1997 [inline]
__se_sys_mremap+0x420/0xb30 mm/mremap.c:1965
__x64_sys_mremap+0x67/0x80 mm/mremap.c:1965
x64_sys_call+0x2944/0x3000 arch/x86/include/generated/asm/syscalls_64.h:26
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000023 -> 0x00000025

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9942 Comm: syz.1.2193 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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