Support strange discontiguous PFN remappings
These get created by some drivers that don't generally even want a pfn remapping at all, but would really mostly prefer to just map pages they've allocated individually instead. For now, create a helper function that turns such an incomplete PFN remapping call into a loop that does that explicit mapping. In the long run we almost certainly want to export a totally different interface for that, though. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -163,6 +163,7 @@ extern unsigned int kobjsize(const void *objp);
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#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */
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#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */
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#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
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#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
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#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
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#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
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#define VM_INCOMPLETE 0x02000000 /* Strange partial PFN mapping marker */
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#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
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#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
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#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
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#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
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92
mm/memory.c
92
mm/memory.c
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@ -1146,6 +1146,95 @@ int zeromap_page_range(struct vm_area_struct *vma,
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return err;
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return err;
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}
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}
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/*
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* This is the old fallback for page remapping.
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*
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* For historical reasons, it only allows reserved pages. Only
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* old drivers should use this, and they needed to mark their
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* pages reserved for the old functions anyway.
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*/
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static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
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{
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int retval;
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pgd_t * pgd;
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pud_t * pud;
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pmd_t * pmd;
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pte_t * pte;
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spinlock_t *ptl;
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retval = -EINVAL;
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if (PageAnon(page) || !PageReserved(page))
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goto out;
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retval = -ENOMEM;
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flush_dcache_page(page);
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pgd = pgd_offset(mm, addr);
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pud = pud_alloc(mm, pgd, addr);
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if (!pud)
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goto out;
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pmd = pmd_alloc(mm, pud, addr);
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if (!pmd)
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goto out;
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pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
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if (!pte)
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goto out;
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retval = -EBUSY;
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if (!pte_none(*pte))
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goto out_unlock;
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/* Ok, finally just insert the thing.. */
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get_page(page);
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inc_mm_counter(mm, file_rss);
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page_add_file_rmap(page);
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set_pte_at(mm, addr, pte, mk_pte(page, prot));
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retval = 0;
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out_unlock:
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pte_unmap_unlock(pte, ptl);
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out:
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return retval;
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}
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/*
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* Somebody does a pfn remapping that doesn't actually work as a vma.
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*
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* Do it as individual pages instead, and warn about it. It's bad form,
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* and very inefficient.
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*/
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static int incomplete_pfn_remap(struct vm_area_struct *vma,
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unsigned long start, unsigned long end,
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unsigned long pfn, pgprot_t prot)
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{
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static int warn = 10;
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struct page *page;
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int retval;
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if (!(vma->vm_flags & VM_INCOMPLETE)) {
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if (warn) {
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warn--;
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printk("%s does an incomplete pfn remapping", current->comm);
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dump_stack();
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}
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}
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vma->vm_flags |= VM_INCOMPLETE | VM_IO | VM_RESERVED;
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if (start < vma->vm_start || end > vma->vm_end)
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return -EINVAL;
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if (!pfn_valid(pfn))
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return -EINVAL;
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retval = 0;
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page = pfn_to_page(pfn);
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while (start < end) {
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retval = insert_page(vma->vm_mm, start, page, prot);
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if (retval < 0)
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break;
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start += PAGE_SIZE;
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page++;
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}
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return retval;
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}
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/*
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/*
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* maps a range of physical memory into the requested pages. the old
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* maps a range of physical memory into the requested pages. the old
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* mappings are removed. any references to nonexistent pages results
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* mappings are removed. any references to nonexistent pages results
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@ -1220,6 +1309,9 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
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struct mm_struct *mm = vma->vm_mm;
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struct mm_struct *mm = vma->vm_mm;
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int err;
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int err;
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if (addr != vma->vm_start || end != vma->vm_end)
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return incomplete_pfn_remap(vma, addr, end, pfn, prot);
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/*
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/*
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* Physically remapped pages are special. Tell the
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* Physically remapped pages are special. Tell the
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* rest of the world about it:
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* rest of the world about it:
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