On 2022/12/15 4:04, Peter Xu wrote:
When fork(), dst_vma is not guaranteed to have VM_UFFD_WP even if src may have it and has pte marker installed. The warning is improper along with the comment. The right thing is to inherit the pte marker when needed, or keep the dst pte empty.
A vague guess is this happened by an accident when there's the prior patch to introduce src/dst vma into this helper during the uffd-wp feature got developed and I probably messed up in the rebase, since if we replace dst_vma with src_vma the warning & comment it all makes sense too.
Hugetlb did exactly the right here (copy_hugetlb_page_range()). Fix the general path.
Reproducer:
https://github.com/xupengfe/syzkaller_logs/blob/main/221208_115556_copy_page...
Cc: stable@vger.kernel.org # 5.19+ Fixes: c56d1b62cce8 ("mm/shmem: handle uffd-wp during fork()") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216808 Reported-by: Pengfei Xu pengfei.xu@intel.com Signed-off-by: Peter Xu peterx@redhat.com
Looks good to me. Thanks. Reviewed-by: Miaohe Lin linmiaohe@huawei.com
Thanks, Miaohe Lin