mm: re-architect the VM_UNPAGED logic
This replaces the (in my opinion horrible) VM_UNMAPPED logic with very
explicit support for a "remapped page range" aka VM_PFNMAP. It allows a
VM area to contain an arbitrary range of page table entries that the VM
never touches, and never considers to be normal pages.
Any user of "remap_pfn_range()" automatically gets this new
functionality, and doesn't even have to mark the pages reserved or
indeed mark them any other way. It just works. As a side effect, doing
mmap() on /dev/mem works for arbitrary ranges.
Sparc update from David in the next commit.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/fremap.c b/mm/fremap.c
index 007cbad..f851775 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -27,24 +27,20 @@
struct page *page = NULL;
if (pte_present(pte)) {
- unsigned long pfn = pte_pfn(pte);
- flush_cache_page(vma, addr, pfn);
+ flush_cache_page(vma, addr, pte_pfn(pte));
pte = ptep_clear_flush(vma, addr, ptep);
- if (unlikely(!pfn_valid(pfn))) {
- print_bad_pte(vma, pte, addr);
- goto out;
+ page = vm_normal_page(vma, addr, pte);
+ if (page) {
+ if (pte_dirty(pte))
+ set_page_dirty(page);
+ page_remove_rmap(page);
+ page_cache_release(page);
}
- page = pfn_to_page(pfn);
- if (pte_dirty(pte))
- set_page_dirty(page);
- page_remove_rmap(page);
- page_cache_release(page);
} else {
if (!pte_file(pte))
free_swap_and_cache(pte_to_swp_entry(pte));
pte_clear(mm, addr, ptep);
}
-out:
return !!page;
}
@@ -65,8 +61,6 @@
pte_t pte_val;
spinlock_t *ptl;
- BUG_ON(vma->vm_flags & VM_UNPAGED);
-
pgd = pgd_offset(mm, addr);
pud = pud_alloc(mm, pgd, addr);
if (!pud)
@@ -122,8 +116,6 @@
pte_t pte_val;
spinlock_t *ptl;
- BUG_ON(vma->vm_flags & VM_UNPAGED);
-
pgd = pgd_offset(mm, addr);
pud = pud_alloc(mm, pgd, addr);
if (!pud)