[Xen-devel] What's the purpose of VM_FOREIGN

["Li, Xin B" <xin.b.li@xxxxxxxxx>]

It is defined in Mm.h (linux-2.6-xen-sparse\include\linux), and only
used in Memory.c (linux-2.6-xen-sparse\mm) as follow:

#ifdef CONFIG_XEN
                if (vma && (vma->vm_flags & VM_FOREIGN)) {
                        struct page **map = vma->vm_private_data;
                        int offset = (start - vma->vm_start) >>
PAGE_SHIFT;
                        if (map[offset] != NULL) {
                                if (pages) {
                                        struct page *page = map[offset];
                                        
                                        pages[i] = page;
                                        get_page(page);
                                }
                                if (vmas)
                                        vmas[i] = vma;
                                i++;
                                start += PAGE_SIZE;
                                len--;
                                continue;
                        }
                }
#endif

But I never saw when the bit is set, so this code path can not be
reached?
-Xin

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