[PATCH] ia64 memory hotplug for hugetlbpages [2/3]

[Nobuhiko Yoshida]

diff -dupr linux-2.6.7/arch/ia64/mm/hugetlbpage.c linux-2.6.7-RMAP/arch/ia64/mm/hugetlbpage.c
--- linux-2.6.7/arch/ia64/mm/hugetlbpage.c	2004-07-09 15:51:19.000000000 +0900
+++ linux-2.6.7-RMAP/arch/ia64/mm/hugetlbpage.c	2004-07-15 11:28:52.000000000 +0900
@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/hugetlb.h>
 #include <linux/pagemap.h>
+#include <linux/rmap.h>
 #include <linux/smp_lock.h>
 #include <linux/slab.h>
 #include <linux/sysctl.h>
@@ -108,6 +109,7 @@ int copy_hugetlb_page_range(struct mm_st
 		if (!pte_none(entry)) {
 			ptepage = pte_page(entry);
 			get_page(ptepage);
+			page_dup_rmap(ptepage);
 			dst->rss += (HPAGE_SIZE / PAGE_SIZE);
 		}
 		set_pte(dst_pte, entry);
@@ -261,6 +263,7 @@ void unmap_hugepage_range(struct vm_area
 		if (pte_none(*pte))
 			continue;
 		page = pte_page(*pte);
+		page_remove_rmap(page);
 		put_page(page);
 		pte_clear(pte);
 		mm->rss -= (HPAGE_SIZE / PAGE_SIZE);
@@ -315,6 +318,7 @@ int hugetlb_prefault(struct address_spac
 			}
 		}
 		set_huge_pte(mm, vma, page, pte, vma->vm_flags & VM_WRITE);
+		page_add_file_rmap(page);
 	}
 out:
 	spin_unlock(&mm->page_table_lock);
@@ -371,6 +375,7 @@ again:
 	}
 	if (pte_none(*pte)) {
 		set_huge_pte(mm, vma, page, pte, vma->vm_flags & VM_WRITE);
+		page_add_file_rmap(page);
 		flush_tlb_range(vma, address, address + HPAGE_SIZE);
 		update_mmu_cache(vma, address, *pte);
 	} else {
@@ -383,6 +388,89 @@ out:
 	return ret;
 }
 
+/*
+ * At what user virtual address is page expected in vma?
+ */
+static inline unsigned long
+huge_vma_address(struct page *page, struct vm_area_struct *vma)
+{
+	pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+	unsigned long address;
+
+	address = vma->vm_start + ((pgoff - vma->vm_pgoff) << HPAGE_SHIFT);
+	if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
+		/* page should be within any vma from prio_tree_next */
+		BUG_ON(!PageAnon(page));
+		return -EFAULT;
+	}
+	return address;
+}
+
+/*
+ * Try to clear the PTE which map the hugepage.
+ */
+int try_to_unmap_hugepage(struct page *page, struct vm_area_struct *vma,
+			struct list_head *force)
+{
+	pte_t *pte;
+	pte_t pteval;
+	int ret = SWAP_AGAIN;
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long address;
+
+	address = huge_vma_address(page, vma);
+	if (address == -EFAULT)
+		goto out;
+
+	/*
+	 * We need the page_table_lock to protect us from page faults,
+	 * munmap, fork, etc...
+	 */
+	if (!spin_trylock(&mm->page_table_lock))
+		goto out;
+
+	pte = huge_pte_offset(mm, address);
+	if (!pte || pte_none(*pte))
+		goto out_unlock;
+	if (!pte_present(*pte))
+		goto out_unlock;
+
+	if (page_to_pfn(page) != pte_pfn(*pte))
+		goto out_unlock;
+
+	BUG_ON(!vma);
+
+#if 0
+	if ((vma->vm_flags & (VM_LOCKED|VM_RESERVED)) ||
+		ptep_test_and_clear_young(pte)) {
+		ret = SWAP_FAIL;
+		goto out_unlock;
+	}
+#endif
+
+	/* Nuke the page table entry. */
+	flush_cache_page(vma, address);
+	pteval = ptep_get_and_clear(pte);
+	flush_tlb_range(vma, address, address + HPAGE_SIZE);
+
+	/* Move the dirty bit to the physical page now the pte is gone. */
+	if (pte_dirty(pteval))
+		set_page_dirty(page);
+
+	BUG_ON(PageAnon(page));
+
+	mm->rss -= (HPAGE_SIZE / PAGE_SIZE);
+	BUG_ON(!page->mapcount);
+	page->mapcount--;
+	page_cache_release(page);
+
+out_unlock:
+	spin_unlock(&mm->page_table_lock);
+
+out:
+	return ret;
+}
+
 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 		unsigned long pgoff, unsigned long flags)
 {
-
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