[syzbot] [mm?] KCSAN: data-race in __anon_vma_prepare / __vmf_anon_prepare

[syzbot <syzbot+f5d897f5194d92aa1769@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    cfd4039213e7 Merge tag 'io_uring-6.19-20251208' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1554d992580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c3201432211be40f
dashboard link: https://syzkaller.appspot.com/bug?extid=f5d897f5194d92aa1769
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9f556ae6e3c4/disk-cfd40392.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/efcf53c1d459/vmlinux-cfd40392.xz
kernel image: https://storage.googleapis.com/syzbot-assets/858f42961336/bzImage-cfd40392.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f5d897f5194d92aa1769@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __anon_vma_prepare / __vmf_anon_prepare

write to 0xffff88811c751e80 of 8 bytes by task 13471 on cpu 1:
 __anon_vma_prepare+0x172/0x2f0 mm/rmap.c:212
 __vmf_anon_prepare+0x91/0x100 mm/memory.c:3673
 hugetlb_no_page+0x1c4/0x10d0 mm/hugetlb.c:5782
 hugetlb_fault+0x4cf/0xce0 mm/hugetlb.c:-1
 handle_mm_fault+0x1894/0x2c60 mm/memory.c:6578
 do_user_addr_fault+0x3fe/0x1080 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
 fault_in_readable+0xad/0x170 mm/gup.c:-1
 fault_in_iov_iter_readable+0x129/0x210 lib/iov_iter.c:106
 generic_perform_write+0x3cf/0x490 mm/filemap.c:4363
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3490
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x52a/0x960 fs/read_write.c:686
 ksys_pwrite64 fs/read_write.c:793 [inline]
 __do_sys_pwrite64 fs/read_write.c:801 [inline]
 __se_sys_pwrite64 fs/read_write.c:798 [inline]
 __x64_sys_pwrite64+0xfd/0x150 fs/read_write.c:798
 x64_sys_call+0x9f7/0x3000 arch/x86/include/generated/asm/syscalls_64.h:19
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811c751e80 of 8 bytes by task 13473 on cpu 0:
 __vmf_anon_prepare+0x26/0x100 mm/memory.c:3667
 hugetlb_no_page+0x1c4/0x10d0 mm/hugetlb.c:5782
 hugetlb_fault+0x4cf/0xce0 mm/hugetlb.c:-1
 handle_mm_fault+0x1894/0x2c60 mm/memory.c:6578
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x1024/0x1ed0 mm/gup.c:1428
 populate_vma_page_range mm/gup.c:1860 [inline]
 __mm_populate+0x243/0x3a0 mm/gup.c:1963
 mm_populate include/linux/mm.h:3701 [inline]
 vm_mmap_pgoff+0x232/0x2e0 mm/util.c:586
 ksys_mmap_pgoff+0x268/0x310 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+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff888104ecca28

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 13473 Comm: syz.2.3219 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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