On Fri, Feb 17, 2017 at 01:08:55PM -0800, Andrew Morton wrote: > I had a bunch more rejects to fix in that function. Below is the final > result - please check it carefully. Sure, reviewed and this is the diff that remains (vm_shared assignment location is irrelevant, I put it at the end as it's only needed later and not checked in the out_unlock path, err = -EINVAL also is fine to stay): diff --git a/tmp/x b/mm/userfaultfd.c index a3ba029..3ec9aad 100644 --- a/tmp/x +++ b/mm/userfaultfd.c @@ -63,22 +212,17 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, dst_start + len > dst_vma->vm_end) goto out_unlock; - vm_shared = dst_vma->vm_flags & VM_SHARED; - err = -EINVAL; if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) goto out_unlock; + + vm_shared = dst_vma->vm_flags & VM_SHARED; } - err = -EINVAL; if (WARN_ON(dst_addr & (vma_hpagesize - 1) || (len - copied) & (vma_hpagesize - 1))) goto out_unlock; - if (dst_start < dst_vma->vm_start || - dst_start + len > dst_vma->vm_end) - goto out_unlock; - /* * If not shared, ensure the dst_vma has a anon_vma. */ In short there's only the last 4 lines of the above that can be applied. __mcopy_atomic_hugetlb in the first pass (i.e. dst_vma not NULL) is invoked after those checks already have been run in the caller. if (dst_start < dst_vma->vm_start || dst_start + len > dst_vma->vm_end) goto out_unlock; err = -EINVAL; /* * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but * it will overwrite vm_ops, so vma_is_anonymous must return false. */ if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && dst_vma->vm_flags & VM_SHARED)) goto out_unlock; /* * If this is a HUGETLB vma, pass off to appropriate routine */ if (is_vm_hugetlb_page(dst_vma)) return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, src_start, len, zeropage); As usual hugetlbfs takes its own tangent out of the main VM code after various checks have already been done that applies to hugetlbfs too. In the "retry" case the dst_vma is set to NULL and the dst_vma is being searched again and revalidated, and we so we repeat the check. First time it's not needed, for second time it would be a repetition and so it's a noop. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
