[PATCH] core remove PageReserved

Remove PageReserved() calls from core code by tightening VM_RESERVED
handling in mm/ to cover PageReserved functionality.

PageReserved special casing is removed from get_page and put_page.

All setting and clearing of PageReserved is retained, and it is now flagged
in the page_alloc checks to help ensure we don't introduce any refcount
based freeing of Reserved pages.

MAP_PRIVATE, PROT_WRITE of VM_RESERVED regions is tentatively being
deprecated.  We never completely handled it correctly anyway, and is be
reintroduced in future if required (Hugh has a proof of concept).

Once PageReserved() calls are removed from kernel/power/swsusp.c, and all
arch/ and driver code, the Set and Clear calls, and the PG_reserved bit can
be trivially removed.

Last real user of PageReserved is swsusp, which uses PageReserved to
determine whether a struct page points to valid memory or not.  This still
needs to be addressed (a generic page_is_ram() should work).

A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and
thus mapcounted and count towards shared rss).  These writes to the struct
page could cause excessive cacheline bouncing on big systems.  There are a
number of ways this could be addressed if it is an issue.

Signed-off-by: Nick Piggin <npiggin@suse.de>

Refcount bug fix for filemap_xip.c

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

13 files changed, 165 insertions, 104 deletions

diff --git a/mm/bootmem.c b/mm/bootmem.c
index a58699b..e8c5671 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -305,6 +305,7 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
 				if (j + 16 < BITS_PER_LONG)
 					prefetchw(page + j + 16);
 				__ClearPageReserved(page + j);
+				set_page_count(page + j, 0);
 			}
 			__free_pages(page, order);
 			i += BITS_PER_LONG;
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 8c199f5..9354ee2 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -174,6 +174,7 @@ __xip_unmap (struct address_space * mapping,
 	unsigned long address;
 	pte_t *pte;
 	pte_t pteval;
+	struct page *page = ZERO_PAGE(address);
 
 	spin_lock(&mapping->i_mmap_lock);
 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
@@ -185,15 +186,17 @@ __xip_unmap (struct address_space * mapping,
 		 * We need the page_table_lock to protect us from page faults,
 		 * munmap, fork, etc...
 		 */
-		pte = page_check_address(ZERO_PAGE(address), mm,
-					 address);
+		pte = page_check_address(page, mm, address);
 		if (!IS_ERR(pte)) {
 			/* Nuke the page table entry. */
 			flush_cache_page(vma, address, pte_pfn(*pte));
 			pteval = ptep_clear_flush(vma, address, pte);
+			page_remove_rmap(page);
+			dec_mm_counter(mm, file_rss);
 			BUG_ON(pte_dirty(pteval));
 			pte_unmap(pte);
 			spin_unlock(&mm->page_table_lock);
+			page_cache_release(page);
 		}
 	}
 	spin_unlock(&mapping->i_mmap_lock);
@@ -228,7 +231,7 @@ xip_file_nopage(struct vm_area_struct * area,
 
 	page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0);
 	if (!IS_ERR(page)) {
-		return page;
+		goto out;
 	}
 	if (PTR_ERR(page) != -ENODATA)
 		return NULL;
@@ -249,6 +252,8 @@ xip_file_nopage(struct vm_area_struct * area,
 		page = ZERO_PAGE(address);
 	}
 
+out:
+	page_cache_get(page);
 	return page;
 }
 
diff --git a/mm/fremap.c b/mm/fremap.c
index fd7f2a1..224cc15 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -29,19 +29,20 @@ static inline void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
 		return;
 	if (pte_present(pte)) {
 		unsigned long pfn = pte_pfn(pte);
+		struct page *page;
 
 		flush_cache_page(vma, addr, pfn);
 		pte = ptep_clear_flush(vma, addr, ptep);
-		if (pfn_valid(pfn)) {
-			struct page *page = pfn_to_page(pfn);
-			if (!PageReserved(page)) {
-				if (pte_dirty(pte))
-					set_page_dirty(page);
-				page_remove_rmap(page);
-				page_cache_release(page);
-				dec_mm_counter(mm, file_rss);
-			}
+		if (unlikely(!pfn_valid(pfn))) {
+			print_bad_pte(vma, pte, addr);
+			return;
 		}
+		page = pfn_to_page(pfn);
+		if (pte_dirty(pte))
+			set_page_dirty(page);
+		page_remove_rmap(page);
+		page_cache_release(page);
+		dec_mm_counter(mm, file_rss);
 	} else {
 		if (!pte_file(pte))
 			free_swap_and_cache(pte_to_swp_entry(pte));
@@ -65,6 +66,8 @@ int install_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	pgd_t *pgd;
 	pte_t pte_val;
 
+	BUG_ON(vma->vm_flags & VM_RESERVED);
+
 	pgd = pgd_offset(mm, addr);
 	spin_lock(&mm->page_table_lock);
 	
@@ -125,6 +128,8 @@ int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
 	pgd_t *pgd;
 	pte_t pte_val;
 
+	BUG_ON(vma->vm_flags & VM_RESERVED);
+
 	pgd = pgd_offset(mm, addr);
 	spin_lock(&mm->page_table_lock);
 	
diff --git a/mm/madvise.c b/mm/madvise.c
index 20e075d..17aaf3e 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -126,7 +126,7 @@ static long madvise_dontneed(struct vm_area_struct * vma,
 			     unsigned long start, unsigned long end)
 {
 	*prev = vma;
-	if ((vma->vm_flags & VM_LOCKED) || is_vm_hugetlb_page(vma))
+	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_RESERVED))
 		return -EINVAL;
 
 	if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
diff --git a/mm/memory.c b/mm/memory.c
index da642b5..e83f944 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -343,6 +343,23 @@ static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
 #define NO_RSS 2	/* Increment neither file_rss nor anon_rss */
 
 /*
+ * This function is called to print an error when a pte in a
+ * !VM_RESERVED region is found pointing to an invalid pfn (which
+ * is an error.
+ *
+ * The calling function must still handle the error.
+ */
+void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
+{
+	printk(KERN_ERR "Bad pte = %08llx, process = %s, "
+			"vm_flags = %lx, vaddr = %lx\n",
+		(long long)pte_val(pte),
+		(vma->vm_mm == current->mm ? current->comm : "???"),
+		vma->vm_flags, vaddr);
+	dump_stack();
+}
+
+/*
  * copy one vm_area from one task to the other. Assumes the page tables
  * already present in the new task to be cleared in the whole range
  * covered by this vma.
@@ -353,9 +370,10 @@ static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
 
 static inline int
 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
-		pte_t *dst_pte, pte_t *src_pte, unsigned long vm_flags,
+		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 		unsigned long addr)
 {
+	unsigned long vm_flags = vma->vm_flags;
 	pte_t pte = *src_pte;
 	struct page *page;
 	unsigned long pfn;
@@ -375,18 +393,22 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		goto out_set_pte;
 	}
 
+	/* If the region is VM_RESERVED, the mapping is not
+	 * mapped via rmap - duplicate the pte as is.
+	 */
+	if (vm_flags & VM_RESERVED)
+		goto out_set_pte;
+
 	pfn = pte_pfn(pte);
-	/* the pte points outside of valid memory, the
-	 * mapping is assumed to be good, meaningful
-	 * and not mapped via rmap - duplicate the
-	 * mapping as is.
+	/* If the pte points outside of valid memory but
+	 * the region is not VM_RESERVED, we have a problem.
 	 */
-	page = NULL;
-	if (pfn_valid(pfn))
-		page = pfn_to_page(pfn);
+	if (unlikely(!pfn_valid(pfn))) {
+		print_bad_pte(vma, pte, addr);
+		goto out_set_pte; /* try to do something sane */
+	}
 
-	if (!page || PageReserved(page))
-		goto out_set_pte;
+	page = pfn_to_page(pfn);
 
 	/*
 	 * If it's a COW mapping, write protect it both
@@ -418,7 +440,6 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		unsigned long addr, unsigned long end)
 {
 	pte_t *src_pte, *dst_pte;
-	unsigned long vm_flags = vma->vm_flags;
 	int progress = 0;
 	int rss[NO_RSS+1], anon;
 
@@ -446,8 +467,7 @@ again:
 			progress++;
 			continue;
 		}
-		anon = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
-							vm_flags, addr);
+		anon = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma,addr);
 		rss[anon]++;
 		progress += 8;
 	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
@@ -541,10 +561,12 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	return 0;
 }
 
-static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
+static void zap_pte_range(struct mmu_gather *tlb,
+				struct vm_area_struct *vma, pmd_t *pmd,
 				unsigned long addr, unsigned long end,
 				struct zap_details *details)
 {
+	struct mm_struct *mm = tlb->mm;
 	pte_t *pte;
 	int file_rss = 0;
 	int anon_rss = 0;
@@ -556,11 +578,12 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 			continue;
 		if (pte_present(ptent)) {
 			struct page *page = NULL;
-			unsigned long pfn = pte_pfn(ptent);
-			if (pfn_valid(pfn)) {
-				page = pfn_to_page(pfn);
-				if (PageReserved(page))
-					page = NULL;
+			if (!(vma->vm_flags & VM_RESERVED)) {
+				unsigned long pfn = pte_pfn(ptent);
+				if (unlikely(!pfn_valid(pfn)))
+					print_bad_pte(vma, ptent, addr);
+				else
+					page = pfn_to_page(pfn);
 			}
 			if (unlikely(details) && page) {
 				/*
@@ -580,7 +603,7 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 				     page->index > details->last_index))
 					continue;
 			}
-			ptent = ptep_get_and_clear_full(tlb->mm, addr, pte,
+			ptent = ptep_get_and_clear_full(mm, addr, pte,
 							tlb->fullmm);
 			tlb_remove_tlb_entry(tlb, pte, addr);
 			if (unlikely(!page))
@@ -588,7 +611,7 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 			if (unlikely(details) && details->nonlinear_vma
 			    && linear_page_index(details->nonlinear_vma,
 						addr) != page->index)
-				set_pte_at(tlb->mm, addr, pte,
+				set_pte_at(mm, addr, pte,
 					   pgoff_to_pte(page->index));
 			if (PageAnon(page))
 				anon_rss++;
@@ -611,14 +634,15 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 			continue;
 		if (!pte_file(ptent))
 			free_swap_and_cache(pte_to_swp_entry(ptent));
-		pte_clear_full(tlb->mm, addr, pte, tlb->fullmm);
+		pte_clear_full(mm, addr, pte, tlb->fullmm);
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 
-	add_mm_rss(tlb->mm, -file_rss, -anon_rss);
+	add_mm_rss(mm, -file_rss, -anon_rss);
 	pte_unmap(pte - 1);
 }
 
-static inline void zap_pmd_range(struct mmu_gather *tlb, pud_t *pud,
+static inline void zap_pmd_range(struct mmu_gather *tlb,
+				struct vm_area_struct *vma, pud_t *pud,
 				unsigned long addr, unsigned long end,
 				struct zap_details *details)
 {
@@ -630,11 +654,12 @@ static inline void zap_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 		next = pmd_addr_end(addr, end);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
-		zap_pte_range(tlb, pmd, addr, next, details);
+		zap_pte_range(tlb, vma, pmd, addr, next, details);
 	} while (pmd++, addr = next, addr != end);
 }
 
-static inline void zap_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
+static inline void zap_pud_range(struct mmu_gather *tlb,
+				struct vm_area_struct *vma, pgd_t *pgd,
 				unsigned long addr, unsigned long end,
 				struct zap_details *details)
 {
@@ -646,7 +671,7 @@ static inline void zap_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 		next = pud_addr_end(addr, end);
 		if (pud_none_or_clear_bad(pud))
 			continue;
-		zap_pmd_range(tlb, pud, addr, next, details);
+		zap_pmd_range(tlb, vma, pud, addr, next, details);
 	} while (pud++, addr = next, addr != end);
 }
 
@@ -667,7 +692,7 @@ static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		next = pgd_addr_end(addr, end);
 		if (pgd_none_or_clear_bad(pgd))
 			continue;
-		zap_pud_range(tlb, pgd, addr, next, details);
+		zap_pud_range(tlb, vma, pgd, addr, next, details);
 	} while (pgd++, addr = next, addr != end);
 	tlb_end_vma(tlb, vma);
 }
@@ -967,7 +992,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 			continue;
 		}
 
-		if (!vma || (vma->vm_flags & VM_IO)
+		if (!vma || (vma->vm_flags & (VM_IO | VM_RESERVED))
 				|| !(flags & vma->vm_flags))
 			return i ? : -EFAULT;
 
@@ -1027,8 +1052,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 			if (pages) {
 				pages[i] = page;
 				flush_dcache_page(page);
-				if (!PageReserved(page))
-					page_cache_get(page);
+				page_cache_get(page);
 			}
 			if (vmas)
 				vmas[i] = vma;
@@ -1051,7 +1075,11 @@ static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
 	if (!pte)
 		return -ENOMEM;
 	do {
-		pte_t zero_pte = pte_wrprotect(mk_pte(ZERO_PAGE(addr), prot));
+		struct page *page = ZERO_PAGE(addr);
+		pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
+		page_cache_get(page);
+		page_add_file_rmap(page);
+		inc_mm_counter(mm, file_rss);
 		BUG_ON(!pte_none(*pte));
 		set_pte_at(mm, addr, pte, zero_pte);
 	} while (pte++, addr += PAGE_SIZE, addr != end);
@@ -1132,8 +1160,7 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
 		return -ENOMEM;
 	do {
 		BUG_ON(!pte_none(*pte));
-		if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn)))
-			set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
+		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
 		pfn++;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 	pte_unmap(pte - 1);
@@ -1195,8 +1222,8 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 	 * rest of the world about it:
 	 *   VM_IO tells people not to look at these pages
 	 *	(accesses can have side effects).
-	 *   VM_RESERVED tells swapout not to try to touch
-	 *	this region.
+	 *   VM_RESERVED tells the core MM not to "manage" these pages
+         *	(e.g. refcount, mapcount, try to swap them out).
 	 */
 	vma->vm_flags |= VM_IO | VM_RESERVED;
 
@@ -1256,11 +1283,13 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	pte_t entry;
 	int ret = VM_FAULT_MINOR;
 
+	BUG_ON(vma->vm_flags & VM_RESERVED);
+
 	if (unlikely(!pfn_valid(pfn))) {
 		/*
 		 * Page table corrupted: show pte and kill process.
 		 */
-		pte_ERROR(orig_pte);
+		print_bad_pte(vma, orig_pte, address);
 		ret = VM_FAULT_OOM;
 		goto unlock;
 	}
@@ -1284,8 +1313,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	/*
 	 * Ok, we need to copy. Oh, well..
 	 */
-	if (!PageReserved(old_page))
-		page_cache_get(old_page);
+	page_cache_get(old_page);
 	pte_unmap(page_table);
 	spin_unlock(&mm->page_table_lock);
 
@@ -1308,14 +1336,10 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	spin_lock(&mm->page_table_lock);
 	page_table = pte_offset_map(pmd, address);
 	if (likely(pte_same(*page_table, orig_pte))) {
-		if (PageReserved(old_page))
+		page_remove_rmap(old_page);
+		if (!PageAnon(old_page)) {
 			inc_mm_counter(mm, anon_rss);
-		else {
-			page_remove_rmap(old_page);
-			if (!PageAnon(old_page)) {
-				inc_mm_counter(mm, anon_rss);
-				dec_mm_counter(mm, file_rss);
-			}
+			dec_mm_counter(mm, file_rss);
 		}
 		flush_cache_page(vma, address, pfn);
 		entry = mk_pte(new_page, vma->vm_page_prot);
@@ -1769,14 +1793,13 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		unsigned long address, pte_t *page_table, pmd_t *pmd,
 		int write_access)
 {
+	struct page *page = ZERO_PAGE(addr);
 	pte_t entry;
 
 	/* Mapping of ZERO_PAGE - vm_page_prot is readonly */
-	entry = mk_pte(ZERO_PAGE(addr), vma->vm_page_prot);
+	entry = mk_pte(page, vma->vm_page_prot);
 
 	if (write_access) {
-		struct page *page;
-
 		/* Allocate our own private page. */
 		pte_unmap(page_table);
 		spin_unlock(&mm->page_table_lock);
@@ -1800,6 +1823,10 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		lru_cache_add_active(page);
 		SetPageReferenced(page);
 		page_add_anon_rmap(page, vma, address);
+	} else {
+		inc_mm_counter(mm, file_rss);
+		page_add_file_rmap(page);
+		page_cache_get(page);
 	}
 
 	set_pte_at(mm, address, page_table, entry);
@@ -1916,7 +1943,7 @@ retry:
 			inc_mm_counter(mm, anon_rss);
 			lru_cache_add_active(new_page);
 			page_add_anon_rmap(new_page, vma, address);
-		} else if (!PageReserved(new_page)) {
+		} else if (!(vma->vm_flags & VM_RESERVED)) {
 			inc_mm_counter(mm, file_rss);
 			page_add_file_rmap(new_page);
 		}
@@ -1957,7 +1984,7 @@ static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		/*
 		 * Page table corrupted: show pte and kill process.
 		 */
-		pte_ERROR(orig_pte);
+		print_bad_pte(vma, orig_pte, address);
 		return VM_FAULT_OOM;
 	}
 	/* We can then assume vm->vm_ops && vma->vm_ops->populate */
@@ -2232,7 +2259,7 @@ static int __init gate_vma_init(void)
 	gate_vma.vm_start = FIXADDR_USER_START;
 	gate_vma.vm_end = FIXADDR_USER_END;
 	gate_vma.vm_page_prot = PAGE_READONLY;
-	gate_vma.vm_flags = 0;
+	gate_vma.vm_flags = VM_RESERVED;
 	return 0;
 }
 __initcall(gate_vma_init);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 43b1199..11d824f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -223,13 +223,13 @@ static struct mempolicy *mpol_new(int mode, nodemask_t *nodes)
 }
 
 /* Ensure all existing pages follow the policy. */
-static int check_pte_range(struct mm_struct *mm, pmd_t *pmd,
+static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 		unsigned long addr, unsigned long end, nodemask_t *nodes)
 {
 	pte_t *orig_pte;
 	pte_t *pte;
 
-	spin_lock(&mm->page_table_lock);
+	spin_lock(&vma->vm_mm->page_table_lock);
 	orig_pte = pte = pte_offset_map(pmd, addr);
 	do {
 		unsigned long pfn;
@@ -238,18 +238,20 @@ static int check_pte_range(struct mm_struct *mm, pmd_t *pmd,
 		if (!pte_present(*pte))
 			continue;
 		pfn = pte_pfn(*pte);
-		if (!pfn_valid(pfn))
+		if (!pfn_valid(pfn)) {
+			print_bad_pte(vma, *pte, addr);
 			continue;
+		}
 		nid = pfn_to_nid(pfn);
 		if (!node_isset(nid, *nodes))
 			break;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 	pte_unmap(orig_pte);
-	spin_unlock(&mm->page_table_lock);
+	spin_unlock(&vma->vm_mm->page_table_lock);
 	return addr != end;
 }
 
-static inline int check_pmd_range(struct mm_struct *mm, pud_t *pud,
+static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud,
 		unsigned long addr, unsigned long end, nodemask_t *nodes)
 {
 	pmd_t *pmd;
@@ -260,13 +262,13 @@ static inline int check_pmd_range(struct mm_struct *mm, pud_t *pud,
 		next = pmd_addr_end(addr, end);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
-		if (check_pte_range(mm, pmd, addr, next, nodes))
+		if (check_pte_range(vma, pmd, addr, next, nodes))
 			return -EIO;
 	} while (pmd++, addr = next, addr != end);
 	return 0;
 }
 
-static inline int check_pud_range(struct mm_struct *mm, pgd_t *pgd,
+static inline int check_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
 		unsigned long addr, unsigned long end, nodemask_t *nodes)
 {
 	pud_t *pud;
@@ -277,24 +279,24 @@ static inline int check_pud_range(struct mm_struct *mm, pgd_t *pgd,
 		next = pud_addr_end(addr, end);
 		if (pud_none_or_clear_bad(pud))
 			continue;
-		if (check_pmd_range(mm, pud, addr, next, nodes))
+		if (check_pmd_range(vma, pud, addr, next, nodes))
 			return -EIO;
 	} while (pud++, addr = next, addr != end);
 	return 0;
 }
 
-static inline int check_pgd_range(struct mm_struct *mm,
+static inline int check_pgd_range(struct vm_area_struct *vma,
 		unsigned long addr, unsigned long end, nodemask_t *nodes)
 {
 	pgd_t *pgd;
 	unsigned long next;
 
-	pgd = pgd_offset(mm, addr);
+	pgd = pgd_offset(vma->vm_mm, addr);
 	do {
 		next = pgd_addr_end(addr, end);
 		if (pgd_none_or_clear_bad(pgd))
 			continue;
-		if (check_pud_range(mm, pgd, addr, next, nodes))
+		if (check_pud_range(vma, pgd, addr, next, nodes))
 			return -EIO;
 	} while (pgd++, addr = next, addr != end);
 	return 0;
@@ -311,6 +313,8 @@ check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
 	first = find_vma(mm, start);
 	if (!first)
 		return ERR_PTR(-EFAULT);
+	if (first->vm_flags & VM_RESERVED)
+		return ERR_PTR(-EACCES);
 	prev = NULL;
 	for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {
 		if (!vma->vm_next && vma->vm_end < end)
@@ -323,8 +327,7 @@ check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
 				endvma = end;
 			if (vma->vm_start > start)
 				start = vma->vm_start;
-			err = check_pgd_range(vma->vm_mm,
-					   start, endvma, nodes);
+			err = check_pgd_range(vma, start, endvma, nodes);
 			if (err) {
 				first = ERR_PTR(err);
 				break;
diff --git a/mm/mmap.c b/mm/mmap.c
index 459b9f0..8a11179 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1088,6 +1088,17 @@ munmap_back:
 		error = file->f_op->mmap(file, vma);
 		if (error)
 			goto unmap_and_free_vma;
+		if ((vma->vm_flags & (VM_SHARED | VM_WRITE | VM_RESERVED))
+						== (VM_WRITE | VM_RESERVED)) {
+			printk(KERN_WARNING "program %s is using MAP_PRIVATE, "
+				"PROT_WRITE mmap of VM_RESERVED memory, which "
+				"is deprecated. Please report this to "
+				"linux-kernel@vger.kernel.org\n",current->comm);
+			if (vma->vm_ops && vma->vm_ops->close)
+				vma->vm_ops->close(vma);
+			error = -EACCES;
+			goto unmap_and_free_vma;
+		}
 	} else if (vm_flags & VM_SHARED) {
 		error = shmem_zero_setup(vma);
 		if (error)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index b426f01..672a76f 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -125,6 +125,14 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 	 * a MAP_NORESERVE private mapping to writable will now reserve.
 	 */
 	if (newflags & VM_WRITE) {
+		if (oldflags & VM_RESERVED) {
+			BUG_ON(oldflags & VM_WRITE);
+			printk(KERN_WARNING "program %s is using MAP_PRIVATE, "
+				"PROT_WRITE mprotect of VM_RESERVED memory, "
+				"which is deprecated. Please report this to "
+				"linux-kernel@vger.kernel.org\n",current->comm);
+			return -EACCES;
+		}
 		if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_HUGETLB))) {
 			charged = nrpages;
 			if (security_vm_enough_memory(charged))
diff --git a/mm/msync.c b/mm/msync.c
index 3b5f1c5..8603954 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -25,6 +25,7 @@
 static void msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 				unsigned long addr, unsigned long end)
 {
+	struct mm_struct *mm = vma->vm_mm;
 	pte_t *pte;
 	int progress = 0;
 
@@ -37,7 +38,7 @@ again:
 		if (progress >= 64) {
 			progress = 0;
 			if (need_resched() ||
-			    need_lockbreak(&vma->vm_mm->page_table_lock))
+			    need_lockbreak(&mm->page_table_lock))
 				break;
 		}
 		progress++;
@@ -46,11 +47,11 @@ again:
 		if (!pte_maybe_dirty(*pte))
 			continue;
 		pfn = pte_pfn(*pte);
-		if (!pfn_valid(pfn))
+		if (unlikely(!pfn_valid(pfn))) {
+			print_bad_pte(vma, *pte, addr);
 			continue;
+		}
 		page = pfn_to_page(pfn);
-		if (PageReserved(page))
-			continue;
 
 		if (ptep_clear_flush_dirty(vma, addr, pte) ||
 		    page_test_and_clear_dirty(page))
@@ -58,7 +59,7 @@ again:
 		progress += 3;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 	pte_unmap(pte - 1);
-	cond_resched_lock(&vma->vm_mm->page_table_lock);
+	cond_resched_lock(&mm->page_table_lock);
 	if (addr != end)
 		goto again;
 }
@@ -102,8 +103,10 @@ static void msync_page_range(struct vm_area_struct *vma,
 
 	/* For hugepages we can't go walking the page table normally,
 	 * but that's ok, hugetlbfs is memory based, so we don't need
-	 * to do anything more on an msync() */
-	if (is_vm_hugetlb_page(vma))
+	 * to do anything more on an msync().
+	 * Can't do anything with VM_RESERVED regions either.
+	 */
+	if (vma->vm_flags & (VM_HUGETLB|VM_RESERVED))
 		return;
 
 	BUG_ON(addr >= end);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6066323..0541288 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -114,7 +114,8 @@ static void bad_page(const char *function, struct page *page)
 			1 << PG_reclaim |
 			1 << PG_slab    |
 			1 << PG_swapcache |
-			1 << PG_writeback);
+			1 << PG_writeback |
+			1 << PG_reserved );
 	set_page_count(page, 0);
 	reset_page_mapcount(page);
 	page->mapping = NULL;
@@ -244,7 +245,6 @@ static inline int page_is_buddy(struct page *page, int order)
 {
        if (PagePrivate(page)           &&
            (page_order(page) == order) &&
-           !PageReserved(page)         &&
             page_count(page) == 0)
                return 1;
        return 0;
@@ -327,7 +327,8 @@ static inline void free_pages_check(const char *function, struct page *page)
 			1 << PG_reclaim	|
 			1 << PG_slab	|
 			1 << PG_swapcache |
-			1 << PG_writeback )))
+			1 << PG_writeback |
+			1 << PG_reserved )))
 		bad_page(function, page);
 	if (PageDirty(page))
 		__ClearPageDirty(page);
@@ -455,7 +456,8 @@ static void prep_new_page(struct page *page, int order)
 			1 << PG_reclaim	|
 			1 << PG_slab    |
 			1 << PG_swapcache |
-			1 << PG_writeback )))
+			1 << PG_writeback |
+			1 << PG_reserved )))
 		bad_page(__FUNCTION__, page);
 
 	page->flags &= ~(1 << PG_uptodate | 1 << PG_error |
@@ -1016,7 +1018,7 @@ void __pagevec_free(struct pagevec *pvec)
 
 fastcall void __free_pages(struct page *page, unsigned int order)
 {
-	if (!PageReserved(page) && put_page_testzero(page)) {
+	if (put_page_testzero(page)) {
 		if (order == 0)
 			free_hot_page(page);
 		else
@@ -1674,7 +1676,7 @@ void __init memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 			continue;
 		page = pfn_to_page(pfn);
 		set_page_links(page, zone, nid, pfn);
-		set_page_count(page, 0);
+		set_page_count(page, 1);
 		reset_page_mapcount(page);
 		SetPageReserved(page);
 		INIT_LIST_HEAD(&page->lru);
diff --git a/mm/rmap.c b/mm/rmap.c
index 5047576..f69d534 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -443,8 +443,6 @@ int page_referenced(struct page *page, int is_locked, int ignore_token)
 void page_add_anon_rmap(struct page *page,
 	struct vm_area_struct *vma, unsigned long address)
 {
-	BUG_ON(PageReserved(page));
-
 	if (atomic_inc_and_test(&page->_mapcount)) {
 		struct anon_vma *anon_vma = vma->anon_vma;
 
@@ -468,8 +466,7 @@ void page_add_anon_rmap(struct page *page,
 void page_add_file_rmap(struct page *page)
 {
 	BUG_ON(PageAnon(page));
-	if (!pfn_valid(page_to_pfn(page)) || PageReserved(page))
-		return;
+	BUG_ON(!pfn_valid(page_to_pfn(page)));
 
 	if (atomic_inc_and_test(&page->_mapcount))
 		inc_page_state(nr_mapped);
@@ -483,8 +480,6 @@ void page_add_file_rmap(struct page *page)
  */
 void page_remove_rmap(struct page *page)
 {
-	BUG_ON(PageReserved(page));
-
 	if (atomic_add_negative(-1, &page->_mapcount)) {
 		BUG_ON(page_mapcount(page) < 0);
 		/*
@@ -640,13 +635,13 @@ static void try_to_unmap_cluster(unsigned long cursor,
 			continue;
 
 		pfn = pte_pfn(*pte);
-		if (!pfn_valid(pfn))
+		if (unlikely(!pfn_valid(pfn))) {
+			print_bad_pte(vma, *pte, address);
 			continue;
+		}
 
 		page = pfn_to_page(pfn);
 		BUG_ON(PageAnon(page));
-		if (PageReserved(page))
-			continue;
 
 		if (ptep_clear_flush_young(vma, address, pte))
 			continue;
@@ -808,7 +803,6 @@ int try_to_unmap(struct page *page)
 {
 	int ret;
 
-	BUG_ON(PageReserved(page));
 	BUG_ON(!PageLocked(page));
 
 	if (PageAnon(page))
diff --git a/mm/shmem.c b/mm/shmem.c
index 6796311..37777f4 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1506,8 +1506,10 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
 			 */
 			if (!offset)
 				mark_page_accessed(page);
-		} else
+		} else {
 			page = ZERO_PAGE(0);
+			page_cache_get(page);
+		}
 
 		/*
 		 * Ok, we have the page, and it's up-to-date, so
diff --git a/mm/swap.c b/mm/swap.c
index 7771d28..21d15f9 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -48,7 +48,7 @@ void put_page(struct page *page)
 		}
 		return;
 	}
-	if (!PageReserved(page) && put_page_testzero(page))
+	if (put_page_testzero(page))
 		__page_cache_release(page);
 }
 EXPORT_SYMBOL(put_page);
@@ -215,7 +215,7 @@ void release_pages(struct page **pages, int nr, int cold)
 		struct page *page = pages[i];
 		struct zone *pagezone;
 
-		if (PageReserved(page) || !put_page_testzero(page))
+		if (!put_page_testzero(page))
 			continue;
 
 		pagezone = page_zone(page);