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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c072629f05d7 Merge tag 'v6.19-p4' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16af8bfa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c9e86480ac654d3
dashboard link: https://syzkaller.appspot.com/bug?extid=55d5498eaf57f4739a2e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
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/d532c6676f24/disk-c072629f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ae6963bee844/vmlinux-c072629f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/90fbb9a24cec/bzImage-c072629f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+55d549...@syzkaller.appspotmail.com

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

read-write to 0xffff888120891c88 of 4 bytes by task 5502 on cpu 0:
vms_complete_munmap_vmas+0x54/0x440 mm/vma.c:1312
__mmap_complete+0x4a/0x230 mm/vma.c:2581
__mmap_region mm/vma.c:2761 [inline]
mmap_region+0x1833/0x1aa0 mm/vma.c:2830
do_mmap+0x9b2/0xbd0 mm/mmap.c:558
vm_mmap_pgoff+0x183/0x2d0 mm/util.c:581
ksys_mmap_pgoff+0xc1/0x310 mm/mmap.c:604
x64_sys_call+0x16bb/0x3000 arch/x86/include/generated/asm/syscalls_64.h:10
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888120891c88 of 4 bytes by task 5513 on cpu 1:
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+0x43d/0xb50 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+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000033 -> 0x00000034

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5513 Comm: syz.2.540 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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