[moderation] [mm?] KCSAN: data-race in mas_wr_store_entry / mtree_range_walk (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aec2f682d47c Merge tag 'v7.1-p1' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13fcc4ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9c2dc5e8c701bc54
dashboard link: https://syzkaller.appspot.com/bug?extid=40d84d9c007ef8942415
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 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/df8234344013/disk-aec2f682.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/76a15c74e7d7/vmlinux-aec2f682.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fa5d1bc9eef0/bzImage-aec2f682.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+40d84d...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in mas_wr_store_entry / mtree_range_walk

write to 0xffff888103a3aa28 of 8 bytes by task 20285 on cpu 0:
mas_wr_slot_store lib/maple_tree.c:3232 [inline]
mas_wr_store_entry+0x3405/0x5ad0 lib/maple_tree.c:3528
mas_store_prealloc+0x43e/0x690 lib/maple_tree.c:4936
vma_iter_store_overwrite mm/vma.h:616 [inline]
commit_merge+0x6a1/0x720 mm/vma.c:766
vma_expand+0x301/0x460 mm/vma.c:1219
vma_merge_new_range+0x29c/0x320 mm/vma.c:1112
__mmap_region mm/vma.c:2766 [inline]
mmap_region+0x1073/0x2110 mm/vma.c:2856
do_mmap+0x9b2/0xbd0 mm/mmap.c:560
vm_mmap_pgoff+0x183/0x2d0 mm/util.c:581
ksys_mmap_pgoff+0xc1/0x310 mm/mmap.c:606
x64_sys_call+0x14df/0x3020 arch/x86/include/generated/asm/syscalls_64.h:10
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103a3aa28 of 8 bytes by task 20287 on cpu 1:
mtree_range_walk+0x203/0x490 lib/maple_tree.c:2040
mas_state_walk lib/maple_tree.c:2952 [inline]
mas_walk+0x1cc/0x370 lib/maple_tree.c:4366
lock_vma_under_rcu+0xc9/0x210 mm/mmap_lock.c:304
do_user_addr_fault+0x232/0x1050 arch/x86/mm/fault.c:1325
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

value changed: 0x00007f469be26fff -> 0x00007f469be05fff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 20287 Comm: syz.2.4403 Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
==================================================================


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