Merge branch 'master'

60 files changed, 390 insertions, 1544 deletions

diff --git a/arch/alpha/mm/numa.c b/arch/alpha/mm/numa.c
index c7481d59b6d..6d5251254f6 100644
--- a/arch/alpha/mm/numa.c
+++ b/arch/alpha/mm/numa.c
@@ -371,6 +371,8 @@ show_mem(void)
 	show_free_areas();
 	printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
 	for_each_online_node(nid) {
+		unsigned long flags;
+		pgdat_resize_lock(NODE_DATA(nid), &flags);
 		i = node_spanned_pages(nid);
 		while (i-- > 0) {
 			struct page *page = nid_page_nr(nid, i);
@@ -384,6 +386,7 @@ show_mem(void)
 			else
 				shared += page_count(page) - 1;
 		}
+		pgdat_resize_unlock(NODE_DATA(nid), &flags);
 	}
 	printk("%ld pages of RAM\n",total);
 	printk("%ld free pages\n",free);
diff --git a/arch/alpha/mm/remap.c b/arch/alpha/mm/remap.c
index 19817ad3d89..a78356c3ead 100644
--- a/arch/alpha/mm/remap.c
+++ b/arch/alpha/mm/remap.c
@@ -2,7 +2,6 @@
 #include <asm/pgalloc.h>
 #include <asm/cacheflush.h>
 
-/* called with the page_table_lock held */
 static inline void 
 remap_area_pte(pte_t * pte, unsigned long address, unsigned long size, 
 	       unsigned long phys_addr, unsigned long flags)
@@ -31,7 +30,6 @@ remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
 	} while (address && (address < end));
 }
 
-/* called with the page_table_lock held */
 static inline int 
 remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size, 
 	       unsigned long phys_addr, unsigned long flags)
@@ -46,7 +44,7 @@ remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
 	if (address >= end)
 		BUG();
 	do {
-		pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
+		pte_t * pte = pte_alloc_kernel(pmd, address);
 		if (!pte)
 			return -ENOMEM;
 		remap_area_pte(pte, address, end - address, 
@@ -70,7 +68,6 @@ __alpha_remap_area_pages(unsigned long address, unsigned long phys_addr,
 	flush_cache_all();
 	if (address >= end)
 		BUG();
-	spin_lock(&init_mm.page_table_lock);
 	do {
 		pmd_t *pmd;
 		pmd = pmd_alloc(&init_mm, dir, address);
@@ -84,7 +81,6 @@ __alpha_remap_area_pages(unsigned long address, unsigned long phys_addr,
 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
 		dir++;
 	} while (address && (address < end));
-	spin_unlock(&init_mm.page_table_lock);
 	return error;
 }
 
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index a94d75fef59..a917e3dd366 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -139,93 +139,33 @@ struct iwmmxt_sigframe {
 	unsigned long	storage[0x98/4];
 };
 
-static int page_present(struct mm_struct *mm, void __user *uptr, int wr)
-{
-	unsigned long addr = (unsigned long)uptr;
-	pgd_t *pgd = pgd_offset(mm, addr);
-	if (pgd_present(*pgd)) {
-		pmd_t *pmd = pmd_offset(pgd, addr);
-		if (pmd_present(*pmd)) {
-			pte_t *pte = pte_offset_map(pmd, addr);
-			return (pte_present(*pte) && (!wr || pte_write(*pte)));
-		}
-	}
-	return 0;
-}
-
-static int copy_locked(void __user *uptr, void *kptr, size_t size, int write,
-		       void (*copyfn)(void *, void __user *))
-{
-	unsigned char v, __user *userptr = uptr;
-	int err = 0;
-
-	do {
-		struct mm_struct *mm;
-
-		if (write) {
-			__put_user_error(0, userptr, err);
-			__put_user_error(0, userptr + size - 1, err);
-		} else {
-			__get_user_error(v, userptr, err);
-			__get_user_error(v, userptr + size - 1, err);
-		}
-
-		if (err)
-			break;
-
-		mm = current->mm;
-		spin_lock(&mm->page_table_lock);
-		if (page_present(mm, userptr, write) &&
-		    page_present(mm, userptr + size - 1, write)) {
-		    	copyfn(kptr, uptr);
-		} else
-			err = 1;
-		spin_unlock(&mm->page_table_lock);
-	} while (err);
-
-	return err;
-}
-
 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
 {
-	int err = 0;
+	char kbuf[sizeof(*frame) + 8];
+	struct iwmmxt_sigframe *kframe;
 
 	/* the iWMMXt context must be 64 bit aligned */
-	WARN_ON((unsigned long)frame & 7);
-
-	__put_user_error(IWMMXT_MAGIC0, &frame->magic0, err);
-	__put_user_error(IWMMXT_MAGIC1, &frame->magic1, err);
-
-	/*
-	 * iwmmxt_task_copy() doesn't check user permissions.
-	 * Let's do a dummy write on the upper boundary to ensure
-	 * access to user mem is OK all way up.
-	 */
-	err |= copy_locked(&frame->storage, current_thread_info(),
-			   sizeof(frame->storage), 1, iwmmxt_task_copy);
-	return err;
+	kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+	kframe->magic0 = IWMMXT_MAGIC0;
+	kframe->magic1 = IWMMXT_MAGIC1;
+	iwmmxt_task_copy(current_thread_info(), &kframe->storage);
+	return __copy_to_user(frame, kframe, sizeof(*frame));
 }
 
 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 {
-	unsigned long magic0, magic1;
-	int err = 0;
+	char kbuf[sizeof(*frame) + 8];
+	struct iwmmxt_sigframe *kframe;
 
-	/* the iWMMXt context is 64 bit aligned */
-	WARN_ON((unsigned long)frame & 7);
-
-	/*
-	 * Validate iWMMXt context signature.
-	 * Also, iwmmxt_task_restore() doesn't check user permissions.
-	 * Let's do a dummy write on the upper boundary to ensure
-	 * access to user mem is OK all way up.
-	 */
-	__get_user_error(magic0, &frame->magic0, err);
-	__get_user_error(magic1, &frame->magic1, err);
-	if (!err && magic0 == IWMMXT_MAGIC0 && magic1 == IWMMXT_MAGIC1)
-		err = copy_locked(&frame->storage, current_thread_info(),
-				  sizeof(frame->storage), 0, iwmmxt_task_restore);
-	return err;
+	/* the iWMMXt context must be 64 bit aligned */
+	kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+	if (__copy_from_user(kframe, frame, sizeof(*frame)))
+		return -1;
+	if (kframe->magic0 != IWMMXT_MAGIC0 ||
+	    kframe->magic1 != IWMMXT_MAGIC1)
+		return -1;
+	iwmmxt_task_restore(current_thread_info(), &kframe->storage);
+	return 0;
 }
 
 #endif
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index baa09601a64..66e5a0516f2 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -483,29 +483,33 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 		unsigned long addr = regs->ARM_r2;
 		struct mm_struct *mm = current->mm;
 		pgd_t *pgd; pmd_t *pmd; pte_t *pte;
+		spinlock_t *ptl;
 
 		regs->ARM_cpsr &= ~PSR_C_BIT;
-		spin_lock(&mm->page_table_lock);
+		down_read(&mm->mmap_sem);
 		pgd = pgd_offset(mm, addr);
 		if (!pgd_present(*pgd))
 			goto bad_access;
 		pmd = pmd_offset(pgd, addr);
 		if (!pmd_present(*pmd))
 			goto bad_access;
-		pte = pte_offset_map(pmd, addr);
-		if (!pte_present(*pte) || !pte_write(*pte))
+		pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+		if (!pte_present(*pte) || !pte_write(*pte)) {
+			pte_unmap_unlock(pte, ptl);
 			goto bad_access;
+		}
 		val = *(unsigned long *)addr;
 		val -= regs->ARM_r0;
 		if (val == 0) {
 			*(unsigned long *)addr = regs->ARM_r1;
 			regs->ARM_cpsr |= PSR_C_BIT;
 		}
-		spin_unlock(&mm->page_table_lock);
+		pte_unmap_unlock(pte, ptl);
+		up_read(&mm->mmap_sem);
 		return val;
 
 		bad_access:
-		spin_unlock(&mm->page_table_lock);
+		up_read(&mm->mmap_sem);
 		/* simulate a write access fault */
 		do_DataAbort(addr, 15 + (1 << 11), regs);
 		return -1;
diff --git a/arch/arm/mm/consistent.c b/arch/arm/mm/consistent.c
index 82f4d5e27c5..47b0b767f08 100644
--- a/arch/arm/mm/consistent.c
+++ b/arch/arm/mm/consistent.c
@@ -397,8 +397,6 @@ static int __init consistent_init(void)
 	pte_t *pte;
 	int ret = 0;
 
-	spin_lock(&init_mm.page_table_lock);
-
 	do {
 		pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
 		pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
@@ -409,7 +407,7 @@ static int __init consistent_init(void)
 		}
 		WARN_ON(!pmd_none(*pmd));
 
-		pte = pte_alloc_kernel(&init_mm, pmd, CONSISTENT_BASE);
+		pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
 		if (!pte) {
 			printk(KERN_ERR "%s: no pte tables\n", __func__);
 			ret = -ENOMEM;
@@ -419,8 +417,6 @@ static int __init consistent_init(void)
 		consistent_pte = pte;
 	} while (0);
 
-	spin_unlock(&init_mm.page_table_lock);
-
 	return ret;
 }
 
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index be4ab3d73c9..7fc1b35a674 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -26,6 +26,11 @@ static unsigned long shared_pte_mask = L_PTE_CACHEABLE;
 /*
  * We take the easy way out of this problem - we make the
  * PTE uncacheable.  However, we leave the write buffer on.
+ *
+ * Note that the pte lock held when calling update_mmu_cache must also
+ * guard the pte (somewhere else in the same mm) that we modify here.
+ * Therefore those configurations which might call adjust_pte (those
+ * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
  */
 static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
 {
@@ -127,7 +132,7 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page);
  *  2. If we have multiple shared mappings of the same space in
  *     an object, we need to deal with the cache aliasing issues.
  *
- * Note that the page_table_lock will be held.
+ * Note that the pte lock will be held.
  */
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
 {
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 6fb1258df1b..0f128c28fee 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -75,7 +75,7 @@ remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
 
 	pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
 	do {
-		pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
+		pte_t * pte = pte_alloc_kernel(pmd, address);
 		if (!pte)
 			return -ENOMEM;
 		remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
@@ -97,7 +97,6 @@ remap_area_pages(unsigned long start, unsigned long phys_addr,
 	phys_addr -= address;
 	dir = pgd_offset(&init_mm, address);
 	BUG_ON(address >= end);
-	spin_lock(&init_mm.page_table_lock);
 	do {
 		pmd_t *pmd = pmd_alloc(&init_mm, dir, address);
 		if (!pmd) {
@@ -114,7 +113,6 @@ remap_area_pages(unsigned long start, unsigned long phys_addr,
 		dir++;
 	} while (address && (address < end));
 
-	spin_unlock(&init_mm.page_table_lock);
 	flush_cache_vmap(start, end);
 	return err;
 }
diff --git a/arch/arm/mm/mm-armv.c b/arch/arm/mm/mm-armv.c
index 61bc2fa0511..1221fdde176 100644
--- a/arch/arm/mm/mm-armv.c
+++ b/arch/arm/mm/mm-armv.c
@@ -180,11 +180,6 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
 
 	if (!vectors_high()) {
 		/*
-		 * This lock is here just to satisfy pmd_alloc and pte_lock
-		 */
-		spin_lock(&mm->page_table_lock);
-
-		/*
 		 * On ARM, first page must always be allocated since it
 		 * contains the machine vectors.
 		 */
@@ -201,23 +196,14 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
 		set_pte(new_pte, *init_pte);
 		pte_unmap_nested(init_pte);
 		pte_unmap(new_pte);
-
-		spin_unlock(&mm->page_table_lock);
 	}
 
 	return new_pgd;
 
 no_pte:
-	spin_unlock(&mm->page_table_lock);
 	pmd_free(new_pmd);
-	free_pages((unsigned long)new_pgd, 2);
-	return NULL;
-
 no_pmd:
-	spin_unlock(&mm->page_table_lock);
 	free_pages((unsigned long)new_pgd, 2);
-	return NULL;
-
 no_pgd:
 	return NULL;
 }
@@ -243,6 +229,7 @@ void free_pgd_slow(pgd_t *pgd)
 	pte = pmd_page(*pmd);
 	pmd_clear(pmd);
 	dec_page_state(nr_page_table_pages);
+	pte_lock_deinit(pte);
 	pte_free(pte);
 	pmd_free(pmd);
 free:
diff --git a/arch/arm/oprofile/backtrace.c b/arch/arm/oprofile/backtrace.c
index df35c452a8b..7c22c12618c 100644
--- a/arch/arm/oprofile/backtrace.c
+++ b/arch/arm/oprofile/backtrace.c
@@ -49,42 +49,22 @@ static struct frame_tail* kernel_backtrace(struct frame_tail *tail)
 
 static struct frame_tail* user_backtrace(struct frame_tail *tail)
 {
-	struct frame_tail buftail;
+	struct frame_tail buftail[2];
 
-	/* hardware pte might not be valid due to dirty/accessed bit emulation
-	 * so we use copy_from_user and benefit from exception fixups */
-	if (copy_from_user(&buftail, tail, sizeof(struct frame_tail)))
+	/* Also check accessibility of one struct frame_tail beyond */
+	if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
+		return NULL;
+	if (__copy_from_user_inatomic(buftail, tail, sizeof(buftail)))
 		return NULL;
 
-	oprofile_add_trace(buftail.lr);
+	oprofile_add_trace(buftail[0].lr);
 
 	/* frame pointers should strictly progress back up the stack
 	 * (towards higher addresses) */
-	if (tail >= buftail.fp)
+	if (tail >= buftail[0].fp)
 		return NULL;
 
-	return buftail.fp-1;
-}
-
-/* Compare two addresses and see if they're on the same page */
-#define CMP_ADDR_EQUAL(x,y,offset) ((((unsigned long) x) >> PAGE_SHIFT) \
-	== ((((unsigned long) y) + offset) >> PAGE_SHIFT))
-
-/* check that the page(s) containing the frame tail are present */
-static int pages_present(struct frame_tail *tail)
-{
-	struct mm_struct * mm = current->mm;
-
-	if (!check_user_page_readable(mm, (unsigned long)tail))
-		return 0;
-
-	if (CMP_ADDR_EQUAL(tail, tail, 8))
-		return 1;
-
-	if (!check_user_page_readable(mm, ((unsigned long)tail) + 8))
-		return 0;
-
-	return 1;
+	return buftail[0].fp-1;
 }
 
 /*
@@ -118,7 +98,6 @@ static int valid_kernel_stack(struct frame_tail *tail, struct pt_regs *regs)
 void arm_backtrace(struct pt_regs * const regs, unsigned int depth)
 {
 	struct frame_tail *tail;
-	unsigned long last_address = 0;
 
 	tail = ((struct frame_tail *) regs->ARM_fp) - 1;
 
@@ -132,13 +111,6 @@ void arm_backtrace(struct pt_regs * const regs, unsigned int depth)
 		return;
 	}
 
-	while (depth-- && tail && !((unsigned long) tail & 3)) {
-		if ((!CMP_ADDR_EQUAL(last_address, tail, 0)
-			|| !CMP_ADDR_EQUAL(last_address, tail, 8))
-				&& !pages_present(tail))
-			return;
-		last_address = (unsigned long) tail;
+	while (depth-- && tail && !((unsigned long) tail & 3))
 		tail = user_backtrace(tail);
-	}
 }
-
diff --git a/arch/arm26/mm/memc.c b/arch/arm26/mm/memc.c
index 8e8a2bb2487..34def6397c3 100644
--- a/arch/arm26/mm/memc.c
+++ b/arch/arm26/mm/memc.c
@@ -79,12 +79,6 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
 		goto no_pgd;
 
 	/*
-	 * This lock is here just to satisfy pmd_alloc and pte_lock
-         * FIXME: I bet we could avoid taking it pretty much altogether
-	 */
-	spin_lock(&mm->page_table_lock);
-
-	/*
 	 * On ARM, first page must always be allocated since it contains
 	 * the machine vectors.
 	 */
@@ -92,7 +86,7 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
 	if (!new_pmd)
 		goto no_pmd;
 
-	new_pte = pte_alloc_kernel(mm, new_pmd, 0);
+	new_pte = pte_alloc_map(mm, new_pmd, 0);
 	if (!new_pte)
 		goto no_pte;
 
@@ -101,6 +95,7 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
 	init_pte = pte_offset(init_pmd, 0);
 
 	set_pte(new_pte, *init_pte);
+	pte_unmap(new_pte);
 
 	/*
 	 * the page table entries are zeroed
@@ -112,23 +107,14 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
 	memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
 		(PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
 
-	spin_unlock(&mm->page_table_lock);
-
 	/* update MEMC tables */
 	cpu_memc_update_all(new_pgd);
 	return new_pgd;
 
 no_pte:
-	spin_unlock(&mm->page_table_lock);
 	pmd_free(new_pmd);
-	free_pgd_slow(new_pgd);
-	return NULL;
-
 no_pmd:
-	spin_unlock(&mm->page_table_lock);
 	free_pgd_slow(new_pgd);
-	return NULL;
-
 no_pgd:
 	return NULL;
 }
diff --git a/arch/cris/arch-v32/mm/tlb.c b/arch/cris/arch-v32/mm/tlb.c
index 8233406798d..b08a28bb58a 100644
--- a/arch/cris/arch-v32/mm/tlb.c
+++ b/arch/cris/arch-v32/mm/tlb.c
@@ -175,6 +175,8 @@ init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 	return 0;
 }
 
+static DEFINE_SPINLOCK(mmu_context_lock);
+
 /* Called in schedule() just before actually doing the switch_to. */
 void
 switch_mm(struct mm_struct *prev, struct mm_struct *next,
@@ -183,10 +185,10 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	int cpu = smp_processor_id();
 
 	/* Make sure there is a MMU context. */
-	spin_lock(&next->page_table_lock);
+	spin_lock(&mmu_context_lock);
 	get_mmu_context(next);
 	cpu_set(cpu, next->cpu_vm_mask);
-	spin_unlock(&next->page_table_lock);
+	spin_unlock(&mmu_context_lock);
 
 	/*
 	 * Remember the pgd for the fault handlers. Keep a seperate copy of it
diff --git a/arch/cris/mm/ioremap.c b/arch/cris/mm/ioremap.c
index ebba11e270f..a92ac987758 100644
--- a/arch/cris/mm/ioremap.c
+++ b/arch/cris/mm/ioremap.c
@@ -52,7 +52,7 @@ static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned lo
 	if (address >= end)
 		BUG();
 	do {
-		pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
+		pte_t * pte = pte_alloc_kernel(pmd, address);
 		if (!pte)
 			return -ENOMEM;
 		remap_area_pte(pte, address, end - address, address + phys_addr, prot);
@@ -74,7 +74,6 @@ static int remap_area_pages(unsigned long address, unsigned long phys_addr,
 	flush_cache_all();
 	if (address >= end)
 		BUG();
-	spin_lock(&init_mm.page_table_lock);
 	do {
 		pud_t *pud;
 		pmd_t *pmd;
@@ -94,7 +93,6 @@ static int remap_area_pages(unsigned long address, unsigned long phys_addr,
 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
 		dir++;
 	} while (address && (address < end));
-	spin_unlock(&init_mm.page_table_lock);
 	flush_tlb_all();
 	return error;
 }
diff --git a/arch/frv/mm/dma-alloc.c b/arch/frv/mm/dma-alloc.c
index cfc4f97490c..342823aad75 100644
--- a/arch/frv/mm/dma-alloc.c
+++ b/arch/frv/mm/dma-alloc.c
@@ -55,21 +55,18 @@ static int map_page(unsigned long va, unsigned long pa, pgprot_t prot)
 	pte_t *pte;
 	int err = -ENOMEM;
 
-	spin_lock(&init_mm.page_table_lock);
-
 	/* Use upper 10 bits of VA to index the first level map */
 	pge = pgd_offset_k(va);
 	pue = pud_offset(pge, va);
 	pme = pmd_offset(pue, va);
 
 	/* Use middle 10 bits of VA to index the second-level map */
-	pte = pte_alloc_kernel(&init_mm, pme, va);
+	pte = pte_alloc_kernel(pme, va);
 	if (pte != 0) {
 		err = 0;
 		set_pte(pte, mk_pte_phys(pa & PAGE_MASK, prot));
 	}
 
-	spin_unlock(&init_mm.page_table_lock);
 	return err;
 }
 
diff --git a/arch/frv/mm/pgalloc.c b/arch/frv/mm/pgalloc.c
index 4eaec0f3525..2c67dfe5a6b 100644
--- a/arch/frv/mm/pgalloc.c
+++ b/arch/frv/mm/pgalloc.c
@@ -87,14 +87,14 @@ static inline void pgd_list_add(pgd_t *pgd)
 	if (pgd_list)
 		pgd_list->private = (unsigned long) &page->index;
 	pgd_list = page;
-	page->private = (unsigned long) &pgd_list;
+	set_page_private(page, (unsigned long)&pgd_list);
 }
 
 static inline void pgd_list_del(pgd_t *pgd)
 {
 	struct page *next, **pprev, *page = virt_to_page(pgd);
 	next =