diff --git a/src/kernel/linux/v4.19/mm/vmalloc.c b/src/kernel/linux/v4.19/mm/vmalloc.c
new file mode 100644
index 0000000..bf26d40
--- /dev/null
+++ b/src/kernel/linux/v4.19/mm/vmalloc.c
@@ -0,0 +1,2775 @@
+/*
+ *  linux/mm/vmalloc.c
+ *
+ *  Copyright (C) 1993  Linus Torvalds
+ *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
+ *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
+ *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
+ *  Numa awareness, Christoph Lameter, SGI, June 2005
+ */
+
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/highmem.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/debugobjects.h>
+#include <linux/kallsyms.h>
+#include <linux/list.h>
+#include <linux/notifier.h>
+#include <linux/rbtree.h>
+#include <linux/radix-tree.h>
+#include <linux/rcupdate.h>
+#include <linux/pfn.h>
+#include <linux/kmemleak.h>
+#include <linux/atomic.h>
+#include <linux/compiler.h>
+#include <linux/llist.h>
+#include <linux/bitops.h>
+
+#include <linux/uaccess.h>
+#include <asm/tlbflush.h>
+#include <asm/shmparam.h>
+
+#include "internal.h"
+
+struct vfree_deferred {
+	struct llist_head list;
+	struct work_struct wq;
+};
+static DEFINE_PER_CPU(struct vfree_deferred, vfree_deferred);
+
+static void __vunmap(const void *, int);
+
+static void free_work(struct work_struct *w)
+{
+	struct vfree_deferred *p = container_of(w, struct vfree_deferred, wq);
+	struct llist_node *t, *llnode;
+
+	llist_for_each_safe(llnode, t, llist_del_all(&p->list))
+		__vunmap((void *)llnode, 1);
+}
+
+/*** Page table manipulation functions ***/
+
+static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
+{
+	pte_t *pte;
+
+	pte = pte_offset_kernel(pmd, addr);
+	do {
+		pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
+		WARN_ON(!pte_none(ptent) && !pte_present(ptent));
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+}
+
+static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_clear_huge(pmd))
+			continue;
+		if (pmd_none_or_clear_bad(pmd))
+			continue;
+		vunmap_pte_range(pmd, addr, next);
+	} while (pmd++, addr = next, addr != end);
+}
+
+static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pud = pud_offset(p4d, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_clear_huge(pud))
+			continue;
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		vunmap_pmd_range(pud, addr, next);
+	} while (pud++, addr = next, addr != end);
+}
+
+static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+	p4d_t *p4d;
+	unsigned long next;
+
+	p4d = p4d_offset(pgd, addr);
+	do {
+		next = p4d_addr_end(addr, end);
+		if (p4d_clear_huge(p4d))
+			continue;
+		if (p4d_none_or_clear_bad(p4d))
+			continue;
+		vunmap_pud_range(p4d, addr, next);
+	} while (p4d++, addr = next, addr != end);
+}
+
+static void vunmap_page_range(unsigned long addr, unsigned long end)
+{
+	pgd_t *pgd;
+	unsigned long next;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset_k(addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		vunmap_p4d_range(pgd, addr, next);
+	} while (pgd++, addr = next, addr != end);
+}
+
+static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
+		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+{
+	pte_t *pte;
+
+	/*
+	 * nr is a running index into the array which helps higher level
+	 * callers keep track of where we're up to.
+	 */
+
+	pte = pte_alloc_kernel(pmd, addr);
+	if (!pte)
+		return -ENOMEM;
+	do {
+		struct page *page = pages[*nr];
+
+		if (WARN_ON(!pte_none(*pte)))
+			return -EBUSY;
+		if (WARN_ON(!page))
+			return -ENOMEM;
+		set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
+		(*nr)++;
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	return 0;
+}
+
+static int vmap_pmd_range(pud_t *pud, unsigned long addr,
+		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pmd = pmd_alloc(&init_mm, pud, addr);
+	if (!pmd)
+		return -ENOMEM;
+	do {
+		next = pmd_addr_end(addr, end);
+		if (vmap_pte_range(pmd, addr, next, prot, pages, nr))
+			return -ENOMEM;
+	} while (pmd++, addr = next, addr != end);
+	return 0;
+}
+
+static int vmap_pud_range(p4d_t *p4d, unsigned long addr,
+		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pud = pud_alloc(&init_mm, p4d, addr);
+	if (!pud)
+		return -ENOMEM;
+	do {
+		next = pud_addr_end(addr, end);
+		if (vmap_pmd_range(pud, addr, next, prot, pages, nr))
+			return -ENOMEM;
+	} while (pud++, addr = next, addr != end);
+	return 0;
+}
+
+static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
+		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
+{
+	p4d_t *p4d;
+	unsigned long next;
+
+	p4d = p4d_alloc(&init_mm, pgd, addr);
+	if (!p4d)
+		return -ENOMEM;
+	do {
+		next = p4d_addr_end(addr, end);
+		if (vmap_pud_range(p4d, addr, next, prot, pages, nr))
+			return -ENOMEM;
+	} while (p4d++, addr = next, addr != end);
+	return 0;
+}
+
+/*
+ * Set up page tables in kva (addr, end). The ptes shall have prot "prot", and
+ * will have pfns corresponding to the "pages" array.
+ *
+ * Ie. pte at addr+N*PAGE_SIZE shall point to pfn corresponding to pages[N]
+ */
+static int vmap_page_range_noflush(unsigned long start, unsigned long end,
+				   pgprot_t prot, struct page **pages)
+{
+	pgd_t *pgd;
+	unsigned long next;
+	unsigned long addr = start;
+	int err = 0;
+	int nr = 0;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset_k(addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		err = vmap_p4d_range(pgd, addr, next, prot, pages, &nr);
+		if (err)
+			return err;
+	} while (pgd++, addr = next, addr != end);
+
+	return nr;
+}
+
+static int vmap_page_range(unsigned long start, unsigned long end,
+			   pgprot_t prot, struct page **pages)
+{
+	int ret;
+
+	ret = vmap_page_range_noflush(start, end, prot, pages);
+	flush_cache_vmap(start, end);
+	return ret;
+}
+
+int is_vmalloc_or_module_addr(const void *x)
+{
+	/*
+	 * ARM, x86-64 and sparc64 put modules in a special place,
+	 * and fall back on vmalloc() if that fails. Others
+	 * just put it in the vmalloc space.
+	 */
+#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
+	unsigned long addr = (unsigned long)x;
+	if (addr >= MODULES_VADDR && addr < MODULES_END)
+		return 1;
+#endif
+	return is_vmalloc_addr(x);
+}
+
+/*
+ * Walk a vmap address to the struct page it maps.
+ */
+struct page *vmalloc_to_page(const void *vmalloc_addr)
+{
+	unsigned long addr = (unsigned long) vmalloc_addr;
+	struct page *page = NULL;
+	pgd_t *pgd = pgd_offset_k(addr);
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *ptep, pte;
+
+	/*
+	 * XXX we might need to change this if we add VIRTUAL_BUG_ON for
+	 * architectures that do not vmalloc module space
+	 */
+	VIRTUAL_BUG_ON(!is_vmalloc_or_module_addr(vmalloc_addr));
+
+	if (pgd_none(*pgd))
+		return NULL;
+	p4d = p4d_offset(pgd, addr);
+	if (p4d_none(*p4d))
+		return NULL;
+	pud = pud_offset(p4d, addr);
+
+	/*
+	 * Don't dereference bad PUD or PMD (below) entries. This will also
+	 * identify huge mappings, which we may encounter on architectures
+	 * that define CONFIG_HAVE_ARCH_HUGE_VMAP=y. Such regions will be
+	 * identified as vmalloc addresses by is_vmalloc_addr(), but are
+	 * not [unambiguously] associated with a struct page, so there is
+	 * no correct value to return for them.
+	 */
+	WARN_ON_ONCE(pud_bad(*pud));
+	if (pud_none(*pud) || pud_bad(*pud))
+		return NULL;
+	pmd = pmd_offset(pud, addr);
+	WARN_ON_ONCE(pmd_bad(*pmd));
+	if (pmd_none(*pmd) || pmd_bad(*pmd))
+		return NULL;
+
+	ptep = pte_offset_map(pmd, addr);
+	pte = *ptep;
+	if (pte_present(pte))
+		page = pte_page(pte);
+	pte_unmap(ptep);
+	return page;
+}
+EXPORT_SYMBOL(vmalloc_to_page);
+
+/*
+ * Map a vmalloc()-space virtual address to the physical page frame number.
+ */
+unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
+{
+	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
+}
+EXPORT_SYMBOL(vmalloc_to_pfn);
+
+
+/*** Global kva allocator ***/
+
+#define VM_LAZY_FREE	0x02
+#define VM_VM_AREA	0x04
+
+static DEFINE_SPINLOCK(vmap_area_lock);
+/* Export for kexec only */
+LIST_HEAD(vmap_area_list);
+static LLIST_HEAD(vmap_purge_list);
+static struct rb_root vmap_area_root = RB_ROOT;
+
+/* The vmap cache globals are protected by vmap_area_lock */
+static struct rb_node *free_vmap_cache;
+static unsigned long cached_hole_size;
+static unsigned long cached_vstart;
+static unsigned long cached_align;
+
+static unsigned long vmap_area_pcpu_hole;
+
+static atomic_long_t nr_vmalloc_pages;
+
+unsigned long vmalloc_nr_pages(void)
+{
+	return atomic_long_read(&nr_vmalloc_pages);
+}
+
+static struct vmap_area *__find_vmap_area(unsigned long addr)
+{
+	struct rb_node *n = vmap_area_root.rb_node;
+
+	while (n) {
+		struct vmap_area *va;
+
+		va = rb_entry(n, struct vmap_area, rb_node);
+		if (addr < va->va_start)
+			n = n->rb_left;
+		else if (addr >= va->va_end)
+			n = n->rb_right;
+		else
+			return va;
+	}
+
+	return NULL;
+}
+
+static void __insert_vmap_area(struct vmap_area *va)
+{
+	struct rb_node **p = &vmap_area_root.rb_node;
+	struct rb_node *parent = NULL;
+	struct rb_node *tmp;
+
+	while (*p) {
+		struct vmap_area *tmp_va;
+
+		parent = *p;
+		tmp_va = rb_entry(parent, struct vmap_area, rb_node);
+		if (va->va_start < tmp_va->va_end)
+			p = &(*p)->rb_left;
+		else if (va->va_end > tmp_va->va_start)
+			p = &(*p)->rb_right;
+		else
+			BUG();
+	}
+
+	rb_link_node(&va->rb_node, parent, p);
+	rb_insert_color(&va->rb_node, &vmap_area_root);
+
+	/* address-sort this list */
+	tmp = rb_prev(&va->rb_node);
+	if (tmp) {
+		struct vmap_area *prev;
+		prev = rb_entry(tmp, struct vmap_area, rb_node);
+		list_add_rcu(&va->list, &prev->list);
+	} else
+		list_add_rcu(&va->list, &vmap_area_list);
+}
+
+static void purge_vmap_area_lazy(void);
+
+static BLOCKING_NOTIFIER_HEAD(vmap_notify_list);
+
+/*
+ * Allocate a region of KVA of the specified size and alignment, within the
+ * vstart and vend.
+ */
+static struct vmap_area *alloc_vmap_area(unsigned long size,
+				unsigned long align,
+				unsigned long vstart, unsigned long vend,
+				int node, gfp_t gfp_mask)
+{
+	struct vmap_area *va;
+	struct rb_node *n;
+	unsigned long addr;
+	int purged = 0;
+	struct vmap_area *first;
+
+	BUG_ON(!size);
+	BUG_ON(offset_in_page(size));
+	BUG_ON(!is_power_of_2(align));
+
+	might_sleep();
+
+	va = kmalloc_node(sizeof(struct vmap_area),
+			gfp_mask & GFP_RECLAIM_MASK, node);
+	if (unlikely(!va))
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * Only scan the relevant parts containing pointers to other objects
+	 * to avoid false negatives.
+	 */
+	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask & GFP_RECLAIM_MASK);
+
+retry:
+	spin_lock(&vmap_area_lock);
+	/*
+	 * Invalidate cache if we have more permissive parameters.
+	 * cached_hole_size notes the largest hole noticed _below_
+	 * the vmap_area cached in free_vmap_cache: if size fits
+	 * into that hole, we want to scan from vstart to reuse
+	 * the hole instead of allocating above free_vmap_cache.
+	 * Note that __free_vmap_area may update free_vmap_cache
+	 * without updating cached_hole_size or cached_align.
+	 */
+	if (!free_vmap_cache ||
+			size < cached_hole_size ||
+			vstart < cached_vstart ||
+			align < cached_align) {
+nocache:
+		cached_hole_size = 0;
+		free_vmap_cache = NULL;
+	}
+	/* record if we encounter less permissive parameters */
+	cached_vstart = vstart;
+	cached_align = align;
+
+	/* find starting point for our search */
+	if (free_vmap_cache) {
+		first = rb_entry(free_vmap_cache, struct vmap_area, rb_node);
+		addr = ALIGN(first->va_end, align);
+		if (addr < vstart)
+			goto nocache;
+		if (addr + size < addr)
+			goto overflow;
+
+	} else {
+		addr = ALIGN(vstart, align);
+		if (addr + size < addr)
+			goto overflow;
+
+		n = vmap_area_root.rb_node;
+		first = NULL;
+
+		while (n) {
+			struct vmap_area *tmp;
+			tmp = rb_entry(n, struct vmap_area, rb_node);
+			if (tmp->va_end >= addr) {
+				first = tmp;
+				if (tmp->va_start <= addr)
+					break;
+				n = n->rb_left;
+			} else
+				n = n->rb_right;
+		}
+
+		if (!first)
+			goto found;
+	}
+
+	/* from the starting point, walk areas until a suitable hole is found */
+	while (addr + size > first->va_start && addr + size <= vend) {
+		if (addr + cached_hole_size < first->va_start)
+			cached_hole_size = first->va_start - addr;
+		addr = ALIGN(first->va_end, align);
+		if (addr + size < addr)
+			goto overflow;
+
+		if (list_is_last(&first->list, &vmap_area_list))
+			goto found;
+
+		first = list_next_entry(first, list);
+	}
+
+found:
+	/*
+	 * Check also calculated address against the vstart,
+	 * because it can be 0 because of big align request.
+	 */
+	if (addr + size > vend || addr < vstart)
+		goto overflow;
+
+	va->va_start = addr;
+	va->va_end = addr + size;
+	va->flags = 0;
+	__insert_vmap_area(va);
+	free_vmap_cache = &va->rb_node;
+	spin_unlock(&vmap_area_lock);
+
+	BUG_ON(!IS_ALIGNED(va->va_start, align));
+	BUG_ON(va->va_start < vstart);
+	BUG_ON(va->va_end > vend);
+
+	return va;
+
+overflow:
+	spin_unlock(&vmap_area_lock);
+	if (!purged) {
+		purge_vmap_area_lazy();
+		purged = 1;
+		goto retry;
+	}
+
+	if (gfpflags_allow_blocking(gfp_mask)) {
+		unsigned long freed = 0;
+		blocking_notifier_call_chain(&vmap_notify_list, 0, &freed);
+		if (freed > 0) {
+			purged = 0;
+			goto retry;
+		}
+	}
+
+	if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit())
+		pr_warn("vmap allocation for size %lu failed: use vmalloc=<size> to increase size\n",
+			size);
+	kfree(va);
+	return ERR_PTR(-EBUSY);
+}
+
+int register_vmap_purge_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&vmap_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(register_vmap_purge_notifier);
+
+int unregister_vmap_purge_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&vmap_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier);
+
+static void __free_vmap_area(struct vmap_area *va)
+{
+	BUG_ON(RB_EMPTY_NODE(&va->rb_node));
+
+	if (free_vmap_cache) {
+		if (va->va_end < cached_vstart) {
+			free_vmap_cache = NULL;
+		} else {
+			struct vmap_area *cache;
+			cache = rb_entry(free_vmap_cache, struct vmap_area, rb_node);
+			if (va->va_start <= cache->va_start) {
+				free_vmap_cache = rb_prev(&va->rb_node);
+				/*
+				 * We don't try to update cached_hole_size or
+				 * cached_align, but it won't go very wrong.
+				 */
+			}
+		}
+	}
+	rb_erase(&va->rb_node, &vmap_area_root);
+	RB_CLEAR_NODE(&va->rb_node);
+	list_del_rcu(&va->list);
+
+	/*
+	 * Track the highest possible candidate for pcpu area
+	 * allocation.  Areas outside of vmalloc area can be returned
+	 * here too, consider only end addresses which fall inside
+	 * vmalloc area proper.
+	 */
+	if (va->va_end > VMALLOC_START && va->va_end <= VMALLOC_END)
+		vmap_area_pcpu_hole = max(vmap_area_pcpu_hole, va->va_end);
+
+	kfree_rcu(va, rcu_head);
+}
+
+/*
+ * Free a region of KVA allocated by alloc_vmap_area
+ */
+static void free_vmap_area(struct vmap_area *va)
+{
+	spin_lock(&vmap_area_lock);
+	__free_vmap_area(va);
+	spin_unlock(&vmap_area_lock);
+}
+
+/*
+ * Clear the pagetable entries of a given vmap_area
+ */
+static void unmap_vmap_area(struct vmap_area *va)
+{
+	vunmap_page_range(va->va_start, va->va_end);
+}
+
+/*
+ * lazy_max_pages is the maximum amount of virtual address space we gather up
+ * before attempting to purge with a TLB flush.
+ *
+ * There is a tradeoff here: a larger number will cover more kernel page tables
+ * and take slightly longer to purge, but it will linearly reduce the number of
+ * global TLB flushes that must be performed. It would seem natural to scale
+ * this number up linearly with the number of CPUs (because vmapping activity
+ * could also scale linearly with the number of CPUs), however it is likely
+ * that in practice, workloads might be constrained in other ways that mean
+ * vmap activity will not scale linearly with CPUs. Also, I want to be
+ * conservative and not introduce a big latency on huge systems, so go with
+ * a less aggressive log scale. It will still be an improvement over the old
+ * code, and it will be simple to change the scale factor if we find that it
+ * becomes a problem on bigger systems.
+ */
+static unsigned long lazy_max_pages(void)
+{
+	unsigned int log;
+
+	log = fls(num_online_cpus());
+
+	return log * (32UL * 1024 * 1024 / PAGE_SIZE);
+}
+
+static atomic_t vmap_lazy_nr = ATOMIC_INIT(0);
+
+/*
+ * Serialize vmap purging.  There is no actual criticial section protected
+ * by this look, but we want to avoid concurrent calls for performance
+ * reasons and to make the pcpu_get_vm_areas more deterministic.
+ */
+static DEFINE_MUTEX(vmap_purge_lock);
+
+/* for per-CPU blocks */
+static void purge_fragmented_blocks_allcpus(void);
+
+/*
+ * called before a call to iounmap() if the caller wants vm_area_struct's
+ * immediately freed.
+ */
+void set_iounmap_nonlazy(void)
+{
+	atomic_set(&vmap_lazy_nr, lazy_max_pages()+1);
+}
+
+/*
+ * Purges all lazily-freed vmap areas.
+ */
+static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
+{
+	struct llist_node *valist;
+	struct vmap_area *va;
+	struct vmap_area *n_va;
+	bool do_free = false;
+
+	lockdep_assert_held(&vmap_purge_lock);
+
+	valist = llist_del_all(&vmap_purge_list);
+	llist_for_each_entry(va, valist, purge_list) {
+		if (va->va_start < start)
+			start = va->va_start;
+		if (va->va_end > end)
+			end = va->va_end;
+		do_free = true;
+	}
+
+	if (!do_free)
+		return false;
+
+	flush_tlb_kernel_range(start, end);
+
+	spin_lock(&vmap_area_lock);
+	llist_for_each_entry_safe(va, n_va, valist, purge_list) {
+		int nr = (va->va_end - va->va_start) >> PAGE_SHIFT;
+
+		__free_vmap_area(va);
+		atomic_sub(nr, &vmap_lazy_nr);
+		cond_resched_lock(&vmap_area_lock);
+	}
+	spin_unlock(&vmap_area_lock);
+	return true;
+}
+
+/*
+ * Kick off a purge of the outstanding lazy areas. Don't bother if somebody
+ * is already purging.
+ */
+static void try_purge_vmap_area_lazy(void)
+{
+	if (mutex_trylock(&vmap_purge_lock)) {
+		__purge_vmap_area_lazy(ULONG_MAX, 0);
+		mutex_unlock(&vmap_purge_lock);
+	}
+}
+
+/*
+ * Kick off a purge of the outstanding lazy areas.
+ */
+static void purge_vmap_area_lazy(void)
+{
+	mutex_lock(&vmap_purge_lock);
+	purge_fragmented_blocks_allcpus();
+	__purge_vmap_area_lazy(ULONG_MAX, 0);
+	mutex_unlock(&vmap_purge_lock);
+}
+
+/*
+ * Free a vmap area, caller ensuring that the area has been unmapped
+ * and flush_cache_vunmap had been called for the correct range
+ * previously.
+ */
+static void free_vmap_area_noflush(struct vmap_area *va)
+{
+	int nr_lazy;
+
+	nr_lazy = atomic_add_return((va->va_end - va->va_start) >> PAGE_SHIFT,
+				    &vmap_lazy_nr);
+
+	/* After this point, we may free va at any time */
+	llist_add(&va->purge_list, &vmap_purge_list);
+
+	if (unlikely(nr_lazy > lazy_max_pages()))
+		try_purge_vmap_area_lazy();
+}
+
+/*
+ * Free and unmap a vmap area
+ */
+static void free_unmap_vmap_area(struct vmap_area *va)
+{
+	flush_cache_vunmap(va->va_start, va->va_end);
+	unmap_vmap_area(va);
+	if (debug_pagealloc_enabled())
+		flush_tlb_kernel_range(va->va_start, va->va_end);
+
+	free_vmap_area_noflush(va);
+}
+
+static struct vmap_area *find_vmap_area(unsigned long addr)
+{
+	struct vmap_area *va;
+
+	spin_lock(&vmap_area_lock);
+	va = __find_vmap_area(addr);
+	spin_unlock(&vmap_area_lock);
+
+	return va;
+}
+
+/*** Per cpu kva allocator ***/
+
+/*
+ * vmap space is limited especially on 32 bit architectures. Ensure there is
+ * room for at least 16 percpu vmap blocks per CPU.
+ */
+/*
+ * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able
+ * to #define VMALLOC_SPACE		(VMALLOC_END-VMALLOC_START). Guess
+ * instead (we just need a rough idea)
+ */
+#if BITS_PER_LONG == 32
+#define VMALLOC_SPACE		(128UL*1024*1024)
+#else
+#define VMALLOC_SPACE		(128UL*1024*1024*1024)
+#endif
+
+#define VMALLOC_PAGES		(VMALLOC_SPACE / PAGE_SIZE)
+#define VMAP_MAX_ALLOC		BITS_PER_LONG	/* 256K with 4K pages */
+#define VMAP_BBMAP_BITS_MAX	1024	/* 4MB with 4K pages */
+#define VMAP_BBMAP_BITS_MIN	(VMAP_MAX_ALLOC*2)
+#define VMAP_MIN(x, y)		((x) < (y) ? (x) : (y)) /* can't use min() */
+#define VMAP_MAX(x, y)		((x) > (y) ? (x) : (y)) /* can't use max() */
+#define VMAP_BBMAP_BITS		\
+		VMAP_MIN(VMAP_BBMAP_BITS_MAX,	\
+		VMAP_MAX(VMAP_BBMAP_BITS_MIN,	\
+			VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))
+
+#define VMAP_BLOCK_SIZE		(VMAP_BBMAP_BITS * PAGE_SIZE)
+
+static bool vmap_initialized __read_mostly = false;
+
+struct vmap_block_queue {
+	spinlock_t lock;
+	struct list_head free;
+};
+
+struct vmap_block {
+	spinlock_t lock;
+	struct vmap_area *va;
+	unsigned long free, dirty;
+	unsigned long dirty_min, dirty_max; /*< dirty range */
+	struct list_head free_list;
+	struct rcu_head rcu_head;
+	struct list_head purge;
+};
+
+/* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
+static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);
+
+/*
+ * Radix tree of vmap blocks, indexed by address, to quickly find a vmap block
+ * in the free path. Could get rid of this if we change the API to return a
+ * "cookie" from alloc, to be passed to free. But no big deal yet.
+ */
+static DEFINE_SPINLOCK(vmap_block_tree_lock);
+static RADIX_TREE(vmap_block_tree, GFP_ATOMIC);
+
+/*
+ * We should probably have a fallback mechanism to allocate virtual memory
+ * out of partially filled vmap blocks. However vmap block sizing should be
+ * fairly reasonable according to the vmalloc size, so it shouldn't be a
+ * big problem.
+ */
+
+static unsigned long addr_to_vb_idx(unsigned long addr)
+{
+	addr -= VMALLOC_START & ~(VMAP_BLOCK_SIZE-1);
+	addr /= VMAP_BLOCK_SIZE;
+	return addr;
+}
+
+static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off)
+{
+	unsigned long addr;
+
+	addr = va_start + (pages_off << PAGE_SHIFT);
+	BUG_ON(addr_to_vb_idx(addr) != addr_to_vb_idx(va_start));
+	return (void *)addr;
+}
+
+/**
+ * new_vmap_block - allocates new vmap_block and occupies 2^order pages in this
+ *                  block. Of course pages number can't exceed VMAP_BBMAP_BITS
+ * @order:    how many 2^order pages should be occupied in newly allocated block
+ * @gfp_mask: flags for the page level allocator
+ *
+ * Returns: virtual address in a newly allocated block or ERR_PTR(-errno)
+ */
+static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
+{
+	struct vmap_block_queue *vbq;
+	struct vmap_block *vb;
+	struct vmap_area *va;
+	unsigned long vb_idx;
+	int node, err;
+	void *vaddr;
+
+	node = numa_node_id();
+
+	vb = kmalloc_node(sizeof(struct vmap_block),
+			gfp_mask & GFP_RECLAIM_MASK, node);
+	if (unlikely(!vb))
+		return ERR_PTR(-ENOMEM);
+
+	va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
+					VMALLOC_START, VMALLOC_END,
+					node, gfp_mask);
+	if (IS_ERR(va)) {
+		kfree(vb);
+		return ERR_CAST(va);
+	}
+
+	err = radix_tree_preload(gfp_mask);
+	if (unlikely(err)) {
+		kfree(vb);
+		free_vmap_area(va);
+		return ERR_PTR(err);
+	}
+
+	vaddr = vmap_block_vaddr(va->va_start, 0);
+	spin_lock_init(&vb->lock);
+	vb->va = va;
+	/* At least something should be left free */
+	BUG_ON(VMAP_BBMAP_BITS <= (1UL << order));
+	vb->free = VMAP_BBMAP_BITS - (1UL << order);
+	vb->dirty = 0;
+	vb->dirty_min = VMAP_BBMAP_BITS;
+	vb->dirty_max = 0;
+	INIT_LIST_HEAD(&vb->free_list);
+
+	vb_idx = addr_to_vb_idx(va->va_start);
+	spin_lock(&vmap_block_tree_lock);
+	err = radix_tree_insert(&vmap_block_tree, vb_idx, vb);
+	spin_unlock(&vmap_block_tree_lock);
+	BUG_ON(err);
+	radix_tree_preload_end();
+
+	vbq = &get_cpu_var(vmap_block_queue);
+	spin_lock(&vbq->lock);
+	list_add_tail_rcu(&vb->free_list, &vbq->free);
+	spin_unlock(&vbq->lock);
+	put_cpu_var(vmap_block_queue);
+
+	return vaddr;
+}
+
+static void free_vmap_block(struct vmap_block *vb)
+{
+	struct vmap_block *tmp;
+	unsigned long vb_idx;
+
+	vb_idx = addr_to_vb_idx(vb->va->va_start);
+	spin_lock(&vmap_block_tree_lock);
+	tmp = radix_tree_delete(&vmap_block_tree, vb_idx);
+	spin_unlock(&vmap_block_tree_lock);
+	BUG_ON(tmp != vb);
+
+	free_vmap_area_noflush(vb->va);
+	kfree_rcu(vb, rcu_head);
+}
+
+static void purge_fragmented_blocks(int cpu)
+{
+	LIST_HEAD(purge);
+	struct vmap_block *vb;
+	struct vmap_block *n_vb;
+	struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
+
+		if (!(vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS))
+			continue;
+
+		spin_lock(&vb->lock);
+		if (vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS) {
+			vb->free = 0; /* prevent further allocs after releasing lock */
+			vb->dirty = VMAP_BBMAP_BITS; /* prevent purging it again */
+			vb->dirty_min = 0;
+			vb->dirty_max = VMAP_BBMAP_BITS;
+			spin_lock(&vbq->lock);
+			list_del_rcu(&vb->free_list);
+			spin_unlock(&vbq->lock);
+			spin_unlock(&vb->lock);
+			list_add_tail(&vb->purge, &purge);
+		} else
+			spin_unlock(&vb->lock);
+	}
+	rcu_read_unlock();
+
+	list_for_each_entry_safe(vb, n_vb, &purge, purge) {
+		list_del(&vb->purge);
+		free_vmap_block(vb);
+	}
+}
+
+static void purge_fragmented_blocks_allcpus(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		purge_fragmented_blocks(cpu);
+}
+
+static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
+{
+	struct vmap_block_queue *vbq;
+	struct vmap_block *vb;
+	void *vaddr = NULL;
+	unsigned int order;
+
+	BUG_ON(offset_in_page(size));
+	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
+	if (WARN_ON(size == 0)) {
+		/*
+		 * Allocating 0 bytes isn't what caller wants since
+		 * get_order(0) returns funny result. Just warn and terminate
+		 * early.
+		 */
+		return NULL;
+	}
+	order = get_order(size);
+
+	rcu_read_lock();
+	vbq = &get_cpu_var(vmap_block_queue);
+	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
+		unsigned long pages_off;
+
+		spin_lock(&vb->lock);
+		if (vb->free < (1UL << order)) {
+			spin_unlock(&vb->lock);
+			continue;
+		}
+
+		pages_off = VMAP_BBMAP_BITS - vb->free;
+		vaddr = vmap_block_vaddr(vb->va->va_start, pages_off);
+		vb->free -= 1UL << order;
+		if (vb->free == 0) {
+			spin_lock(&vbq->lock);
+			list_del_rcu(&vb->free_list);
+			spin_unlock(&vbq->lock);
+		}
+
+		spin_unlock(&vb->lock);
+		break;
+	}
+
+	put_cpu_var(vmap_block_queue);
+	rcu_read_unlock();
+
+	/* Allocate new block if nothing was found */
+	if (!vaddr)
+		vaddr = new_vmap_block(order, gfp_mask);
+
+	return vaddr;
+}
+
+static void vb_free(const void *addr, unsigned long size)
+{
+	unsigned long offset;
+	unsigned long vb_idx;
+	unsigned int order;
+	struct vmap_block *vb;
+
+	BUG_ON(offset_in_page(size));
+	BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
+
+	flush_cache_vunmap((unsigned long)addr, (unsigned long)addr + size);
+
+	order = get_order(size);
+
+	offset = (unsigned long)addr & (VMAP_BLOCK_SIZE - 1);
+	offset >>= PAGE_SHIFT;
+
+	vb_idx = addr_to_vb_idx((unsigned long)addr);
+	rcu_read_lock();
+	vb = radix_tree_lookup(&vmap_block_tree, vb_idx);
+	rcu_read_unlock();
+	BUG_ON(!vb);
+
+	vunmap_page_range((unsigned long)addr, (unsigned long)addr + size);
+
+	if (debug_pagealloc_enabled())
+		flush_tlb_kernel_range((unsigned long)addr,
+					(unsigned long)addr + size);
+
+	spin_lock(&vb->lock);
+
+	/* Expand dirty range */
+	vb->dirty_min = min(vb->dirty_min, offset);
+	vb->dirty_max = max(vb->dirty_max, offset + (1UL << order));
+
+	vb->dirty += 1UL << order;
+	if (vb->dirty == VMAP_BBMAP_BITS) {
+		BUG_ON(vb->free);
+		spin_unlock(&vb->lock);
+		free_vmap_block(vb);
+	} else
+		spin_unlock(&vb->lock);
+}
+
+/**
+ * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer
+ *
+ * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily
+ * to amortize TLB flushing overheads. What this means is that any page you
+ * have now, may, in a former life, have been mapped into kernel virtual
+ * address by the vmap layer and so there might be some CPUs with TLB entries
+ * still referencing that page (additional to the regular 1:1 kernel mapping).
+ *
+ * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can
+ * be sure that none of the pages we have control over will have any aliases
+ * from the vmap layer.
+ */
+void vm_unmap_aliases(void)
+{
+	unsigned long start = ULONG_MAX, end = 0;
+	int cpu;
+	int flush = 0;
+
+	if (unlikely(!vmap_initialized))
+		return;
+
+	might_sleep();
+
+	for_each_possible_cpu(cpu) {
+		struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
+		struct vmap_block *vb;
+
+		rcu_read_lock();
+		list_for_each_entry_rcu(vb, &vbq->free, free_list) {
+			spin_lock(&vb->lock);
+			if (vb->dirty) {
+				unsigned long va_start = vb->va->va_start;
+				unsigned long s, e;
+
+				s = va_start + (vb->dirty_min << PAGE_SHIFT);
+				e = va_start + (vb->dirty_max << PAGE_SHIFT);
+
+				start = min(s, start);
+				end   = max(e, end);
+
+				flush = 1;
+			}
+			spin_unlock(&vb->lock);
+		}
+		rcu_read_unlock();
+	}
+
+	mutex_lock(&vmap_purge_lock);
+	purge_fragmented_blocks_allcpus();
+	if (!__purge_vmap_area_lazy(start, end) && flush)
+		flush_tlb_kernel_range(start, end);
+	mutex_unlock(&vmap_purge_lock);
+}
+EXPORT_SYMBOL_GPL(vm_unmap_aliases);
+
+/**
+ * vm_unmap_ram - unmap linear kernel address space set up by vm_map_ram
+ * @mem: the pointer returned by vm_map_ram
+ * @count: the count passed to that vm_map_ram call (cannot unmap partial)
+ */
+void vm_unmap_ram(const void *mem, unsigned int count)
+{
+	unsigned long size = (unsigned long)count << PAGE_SHIFT;
+	unsigned long addr = (unsigned long)mem;
+	struct vmap_area *va;
+
+	might_sleep();
+	BUG_ON(!addr);
+	BUG_ON(addr < VMALLOC_START);
+	BUG_ON(addr > VMALLOC_END);
+	BUG_ON(!PAGE_ALIGNED(addr));
+
+	if (likely(count <= VMAP_MAX_ALLOC)) {
+		debug_check_no_locks_freed(mem, size);
+		vb_free(mem, size);
+		return;
+	}
+
+	va = find_vmap_area(addr);
+	BUG_ON(!va);
+	debug_check_no_locks_freed((void *)va->va_start,
+				    (va->va_end - va->va_start));
+	free_unmap_vmap_area(va);
+}
+EXPORT_SYMBOL(vm_unmap_ram);
+
+/**
+ * vm_map_ram - map pages linearly into kernel virtual address (vmalloc space)
+ * @pages: an array of pointers to the pages to be mapped
+ * @count: number of pages
+ * @node: prefer to allocate data structures on this node
+ * @prot: memory protection to use. PAGE_KERNEL for regular RAM
+ *
+ * If you use this function for less than VMAP_MAX_ALLOC pages, it could be
+ * faster than vmap so it's good.  But if you mix long-life and short-life
+ * objects with vm_map_ram(), it could consume lots of address space through
+ * fragmentation (especially on a 32bit machine).  You could see failures in
+ * the end.  Please use this function for short-lived objects.
+ *
+ * Returns: a pointer to the address that has been mapped, or %NULL on failure
+ */
+void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
+{
+	unsigned long size = (unsigned long)count << PAGE_SHIFT;
+	unsigned long addr;
+	void *mem;
+
+	if (likely(count <= VMAP_MAX_ALLOC)) {
+		mem = vb_alloc(size, GFP_KERNEL);
+		if (IS_ERR(mem))
+			return NULL;
+		addr = (unsigned long)mem;
+	} else {
+		struct vmap_area *va;
+		va = alloc_vmap_area(size, PAGE_SIZE,
+				VMALLOC_START, VMALLOC_END, node, GFP_KERNEL);
+		if (IS_ERR(va))
+			return NULL;
+
+		addr = va->va_start;
+		mem = (void *)addr;
+	}
+	if (vmap_page_range(addr, addr + size, prot, pages) < 0) {
+		vm_unmap_ram(mem, count);
+		return NULL;
+	}
+	return mem;
+}
+EXPORT_SYMBOL(vm_map_ram);
+
+static struct vm_struct *vmlist __initdata;
+/**
+ * vm_area_add_early - add vmap area early during boot
+ * @vm: vm_struct to add
+ *
+ * This function is used to add fixed kernel vm area to vmlist before
+ * vmalloc_init() is called.  @vm->addr, @vm->size, and @vm->flags
+ * should contain proper values and the other fields should be zero.
+ *
+ * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
+ */
+void __init vm_area_add_early(struct vm_struct *vm)
+{
+	struct vm_struct *tmp, **p;
+
+	BUG_ON(vmap_initialized);
+	for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
+		if (tmp->addr >= vm->addr) {
+			BUG_ON(tmp->addr < vm->addr + vm->size);
+			break;
+		} else
+			BUG_ON(tmp->addr + tmp->size > vm->addr);
+	}
+	vm->next = *p;
+	*p = vm;
+}
+
+/**
+ * vm_area_register_early - register vmap area early during boot
+ * @vm: vm_struct to register
+ * @align: requested alignment
+ *
+ * This function is used to register kernel vm area before
+ * vmalloc_init() is called.  @vm->size and @vm->flags should contain
+ * proper values on entry and other fields should be zero.  On return,
+ * vm->addr contains the allocated address.
+ *
+ * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
+ */
+void __init vm_area_register_early(struct vm_struct *vm, size_t align)
+{
+	static size_t vm_init_off __initdata;
+	unsigned long addr;
+
+	addr = ALIGN(VMALLOC_START + vm_init_off, align);
+	vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START;
+
+	vm->addr = (void *)addr;
+
+	vm_area_add_early(vm);
+}
+
+void __init vmalloc_init(void)
+{
+	struct vmap_area *va;
+	struct vm_struct *tmp;
+	int i;
+
+	for_each_possible_cpu(i) {
+		struct vmap_block_queue *vbq;
+		struct vfree_deferred *p;
+
+		vbq = &per_cpu(vmap_block_queue, i);
+		spin_lock_init(&vbq->lock);
+		INIT_LIST_HEAD(&vbq->free);
+		p = &per_cpu(vfree_deferred, i);
+		init_llist_head(&p->list);
+		INIT_WORK(&p->wq, free_work);
+	}
+
+	/* Import existing vmlist entries. */
+	for (tmp = vmlist; tmp; tmp = tmp->next) {
+		va = kzalloc(sizeof(struct vmap_area), GFP_NOWAIT);
+		va->flags = VM_VM_AREA;
+		va->va_start = (unsigned long)tmp->addr;
+		va->va_end = va->va_start + tmp->size;
+		va->vm = tmp;
+		__insert_vmap_area(va);
+	}
+
+	vmap_area_pcpu_hole = VMALLOC_END;
+
+	vmap_initialized = true;
+}
+
+/**
+ * map_kernel_range_noflush - map kernel VM area with the specified pages
+ * @addr: start of the VM area to map
+ * @size: size of the VM area to map
+ * @prot: page protection flags to use
+ * @pages: pages to map
+ *
+ * Map PFN_UP(@size) pages at @addr.  The VM area @addr and @size
+ * specify should have been allocated using get_vm_area() and its
+ * friends.
+ *
+ * NOTE:
+ * This function does NOT do any cache flushing.  The caller is
+ * responsible for calling flush_cache_vmap() on to-be-mapped areas
+ * before calling this function.
+ *
+ * RETURNS:
+ * The number of pages mapped on success, -errno on failure.
+ */
+int map_kernel_range_noflush(unsigned long addr, unsigned long size,
+			     pgprot_t prot, struct page **pages)
+{
+	return vmap_page_range_noflush(addr, addr + size, prot, pages);
+}
+
+/**
+ * unmap_kernel_range_noflush - unmap kernel VM area
+ * @addr: start of the VM area to unmap
+ * @size: size of the VM area to unmap
+ *
+ * Unmap PFN_UP(@size) pages at @addr.  The VM area @addr and @size
+ * specify should have been allocated using get_vm_area() and its
+ * friends.
+ *
+ * NOTE:
+ * This function does NOT do any cache flushing.  The caller is
+ * responsible for calling flush_cache_vunmap() on to-be-mapped areas
+ * before calling this function and flush_tlb_kernel_range() after.
+ */
+void unmap_kernel_range_noflush(unsigned long addr, unsigned long size)
+{
+	vunmap_page_range(addr, addr + size);
+}
+EXPORT_SYMBOL_GPL(unmap_kernel_range_noflush);
+
+/**
+ * unmap_kernel_range - unmap kernel VM area and flush cache and TLB
+ * @addr: start of the VM area to unmap
+ * @size: size of the VM area to unmap
+ *
+ * Similar to unmap_kernel_range_noflush() but flushes vcache before
+ * the unmapping and tlb after.
+ */
+void unmap_kernel_range(unsigned long addr, unsigned long size)
+{
+	unsigned long end = addr + size;
+
+	flush_cache_vunmap(addr, end);
+	vunmap_page_range(addr, end);
+	flush_tlb_kernel_range(addr, end);
+}
+EXPORT_SYMBOL_GPL(unmap_kernel_range);
+
+int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page **pages)
+{
+	unsigned long addr = (unsigned long)area->addr;
+	unsigned long end = addr + get_vm_area_size(area);
+	int err;
+
+	err = vmap_page_range(addr, end, prot, pages);
+
+	return err > 0 ? 0 : err;
+}
+EXPORT_SYMBOL_GPL(map_vm_area);
+
+static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
+			      unsigned long flags, const void *caller)
+{
+	spin_lock(&vmap_area_lock);
+	vm->flags = flags;
+	vm->addr = (void *)va->va_start;
+	vm->size = va->va_end - va->va_start;
+	vm->caller = caller;
+	va->vm = vm;
+	va->flags |= VM_VM_AREA;
+	spin_unlock(&vmap_area_lock);
+}
+
+static void clear_vm_uninitialized_flag(struct vm_struct *vm)
+{
+	/*
+	 * Before removing VM_UNINITIALIZED,
+	 * we should make sure that vm has proper values.
+	 * Pair with smp_rmb() in show_numa_info().
+	 */
+	smp_wmb();
+	vm->flags &= ~VM_UNINITIALIZED;
+}
+
+static struct vm_struct *__get_vm_area_node(unsigned long size,
+		unsigned long align, unsigned long flags, unsigned long start,
+		unsigned long end, int node, gfp_t gfp_mask, const void *caller)
+{
+	struct vmap_area *va;
+	struct vm_struct *area;
+
+	BUG_ON(in_interrupt());
+	size = PAGE_ALIGN(size);
+	if (unlikely(!size))
+		return NULL;
+
+	if (flags & VM_IOREMAP)
+		align = 1ul << clamp_t(int, get_count_order_long(size),
+				       PAGE_SHIFT, IOREMAP_MAX_ORDER);
+
+	area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
+	if (unlikely(!area))
+		return NULL;
+
+	if (!(flags & VM_NO_GUARD))
+		size += PAGE_SIZE;
+
+	va = alloc_vmap_area(size, align, start, end, node, gfp_mask);
+	if (IS_ERR(va)) {
+		kfree(area);
+		return NULL;
+	}
+
+	setup_vmalloc_vm(area, va, flags, caller);
+
+	return area;
+}
+
+struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
+				unsigned long start, unsigned long end)
+{
+	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
+				  GFP_KERNEL, __builtin_return_address(0));
+}
+EXPORT_SYMBOL_GPL(__get_vm_area);
+
+struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
+				       unsigned long start, unsigned long end,
+				       const void *caller)
+{
+	return __get_vm_area_node(size, 1, flags, start, end, NUMA_NO_NODE,
+				  GFP_KERNEL, caller);
+}
+
+/**
+ *	get_vm_area  -  reserve a contiguous kernel virtual area
+ *	@size:		size of the area
+ *	@flags:		%VM_IOREMAP for I/O mappings or VM_ALLOC
+ *
+ *	Search an area of @size in the kernel virtual mapping area,
+ *	and reserved it for out purposes.  Returns the area descriptor
+ *	on success or %NULL on failure.
+ */
+struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
+{
+	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
+				  NUMA_NO_NODE, GFP_KERNEL,
+				  __builtin_return_address(0));
+}
+
+struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
+				const void *caller)
+{
+	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
+				  NUMA_NO_NODE, GFP_KERNEL, caller);
+}
+
+/**
+ *	find_vm_area  -  find a continuous kernel virtual area
+ *	@addr:		base address
+ *
+ *	Search for the kernel VM area starting at @addr, and return it.
+ *	It is up to the caller to do all required locking to keep the returned
+ *	pointer valid.
+ */
+struct vm_struct *find_vm_area(const void *addr)
+{
+	struct vmap_area *va;
+
+	va = find_vmap_area((unsigned long)addr);
+	if (va && va->flags & VM_VM_AREA)
+		return va->vm;
+
+	return NULL;
+}
+
+/**
+ *	remove_vm_area  -  find and remove a continuous kernel virtual area
+ *	@addr:		base address
+ *
+ *	Search for the kernel VM area starting at @addr, and remove it.
+ *	This function returns the found VM area, but using it is NOT safe
+ *	on SMP machines, except for its size or flags.
+ */
+struct vm_struct *remove_vm_area(const void *addr)
+{
+	struct vmap_area *va;
+
+	might_sleep();
+
+	va = find_vmap_area((unsigned long)addr);
+	if (va && va->flags & VM_VM_AREA) {
+		struct vm_struct *vm = va->vm;
+
+		spin_lock(&vmap_area_lock);
+		va->vm = NULL;
+		va->flags &= ~VM_VM_AREA;
+		va->flags |= VM_LAZY_FREE;
+		spin_unlock(&vmap_area_lock);
+
+		kasan_free_shadow(vm);
+		free_unmap_vmap_area(va);
+
+		return vm;
+	}
+	return NULL;
+}
+
+static void __vunmap(const void *addr, int deallocate_pages)
+{
+	struct vm_struct *area;
+
+	if (!addr)
+		return;
+
+	if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)\n",
+			addr))
+		return;
+
+	area = find_vmap_area((unsigned long)addr)->vm;
+	if (unlikely(!area)) {
+		WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
+				addr);
+		return;
+	}
+
+	debug_check_no_locks_freed(area->addr, get_vm_area_size(area));
+	debug_check_no_obj_freed(area->addr, get_vm_area_size(area));
+
+	remove_vm_area(addr);
+	if (deallocate_pages) {
+		int i;
+
+		for (i = 0; i < area->nr_pages; i++) {
+			struct page *page = area->pages[i];
+
+			BUG_ON(!page);
+			__free_pages(page, 0);
+		}
+		atomic_long_sub(area->nr_pages, &nr_vmalloc_pages);
+
+		kvfree(area->pages);
+	}
+
+	kfree(area);
+	return;
+}
+
+static inline void __vfree_deferred(const void *addr)
+{
+	/*
+	 * Use raw_cpu_ptr() because this can be called from preemptible
+	 * context. Preemption is absolutely fine here, because the llist_add()
+	 * implementation is lockless, so it works even if we are adding to
+	 * nother cpu's list.  schedule_work() should be fine with this too.
+	 */
+	struct vfree_deferred *p = raw_cpu_ptr(&vfree_deferred);
+
+	if (llist_add((struct llist_node *)addr, &p->list))
+		schedule_work(&p->wq);
+}
+
+/**
+ *	vfree_atomic  -  release memory allocated by vmalloc()
+ *	@addr:		memory base address
+ *
+ *	This one is just like vfree() but can be called in any atomic context
+ *	except NMIs.
+ */
+void vfree_atomic(const void *addr)
+{
+	BUG_ON(in_nmi());
+
+	kmemleak_free(addr);
+
+	if (!addr)
+		return;
+	__vfree_deferred(addr);
+}
+
+/**
+ *	vfree  -  release memory allocated by vmalloc()
+ *	@addr:		memory base address
+ *
+ *	Free the virtually continuous memory area starting at @addr, as
+ *	obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
+ *	NULL, no operation is performed.
+ *
+ *	Must not be called in NMI context (strictly speaking, only if we don't
+ *	have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
+ *	conventions for vfree() arch-depenedent would be a really bad idea)
+ *
+ *	NOTE: assumes that the object at @addr has a size >= sizeof(llist_node)
+ */
+void vfree(const void *addr)
+{
+	BUG_ON(in_nmi());
+
+	kmemleak_free(addr);
+
+	if (!addr)
+		return;
+	if (unlikely(in_interrupt()))
+		__vfree_deferred(addr);
+	else
+		__vunmap(addr, 1);
+}
+EXPORT_SYMBOL(vfree);
+
+/**
+ *	vunmap  -  release virtual mapping obtained by vmap()
+ *	@addr:		memory base address
+ *
+ *	Free the virtually contiguous memory area starting at @addr,
+ *	which was created from the page array passed to vmap().
+ *
+ *	Must not be called in interrupt context.
+ */
+void vunmap(const void *addr)
+{
+	BUG_ON(in_interrupt());
+	might_sleep();
+	if (addr)
+		__vunmap(addr, 0);
+}
+EXPORT_SYMBOL(vunmap);
+
+/**
+ *	vmap  -  map an array of pages into virtually contiguous space
+ *	@pages:		array of page pointers
+ *	@count:		number of pages to map
+ *	@flags:		vm_area->flags
+ *	@prot:		page protection for the mapping
+ *
+ *	Maps @count pages from @pages into contiguous kernel virtual
+ *	space.
+ */
+void *vmap(struct page **pages, unsigned int count,
+		unsigned long flags, pgprot_t prot)
+{
+	struct vm_struct *area;
+	unsigned long size;		/* In bytes */
+
+	might_sleep();
+
+	if (count > totalram_pages)
+		return NULL;
+
+	size = (unsigned long)count << PAGE_SHIFT;
+	area = get_vm_area_caller(size, flags, __builtin_return_address(0));
+	if (!area)
+		return NULL;
+
+	if (map_vm_area(area, prot, pages)) {
+		vunmap(area->addr);
+		return NULL;
+	}
+
+	return area->addr;
+}
+EXPORT_SYMBOL(vmap);
+
+static void *__vmalloc_node(unsigned long size, unsigned long align,
+			    gfp_t gfp_mask, pgprot_t prot,
+			    int node, const void *caller);
+static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
+				 pgprot_t prot, int node)
+{
+	struct page **pages;
+	unsigned int nr_pages, array_size, i;
+	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
+	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
+	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
+					0 :
+					__GFP_HIGHMEM;
+
+	nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
+	array_size = (nr_pages * sizeof(struct page *));
+
+	area->nr_pages = nr_pages;
+	/* Please note that the recursion is strictly bounded. */
+	if (array_size > PAGE_SIZE) {
+		pages = __vmalloc_node(array_size, 1, nested_gfp|highmem_mask,
+				PAGE_KERNEL, node, area->caller);
+	} else {
+		pages = kmalloc_node(array_size, nested_gfp, node);
+	}
+	area->pages = pages;
+	if (!area->pages) {
+		remove_vm_area(area->addr);
+		kfree(area);
+		return NULL;
+	}
+
+	for (i = 0; i < area->nr_pages; i++) {
+		struct page *page;
+
+		if (node == NUMA_NO_NODE)
+			page = alloc_page(alloc_mask|highmem_mask);
+		else
+			page = alloc_pages_node(node, alloc_mask|highmem_mask, 0);
+
+		if (unlikely(!page)) {
+			/* Successfully allocated i pages, free them in __vunmap() */
+			area->nr_pages = i;
+			atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
+			goto fail;
+		}
+		area->pages[i] = page;
+		if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
+			cond_resched();
+	}
+	atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
+
+	if (map_vm_area(area, prot, pages))
+		goto fail;
+	return area->addr;
+
+fail:
+	warn_alloc(gfp_mask, NULL,
+			  "vmalloc: allocation failure, allocated %ld of %ld bytes",
+			  (area->nr_pages*PAGE_SIZE), area->size);
+	vfree(area->addr);
+	return NULL;
+}
+
+/**
+ *	__vmalloc_node_range  -  allocate virtually contiguous memory
+ *	@size:		allocation size
+ *	@align:		desired alignment
+ *	@start:		vm area range start
+ *	@end:		vm area range end
+ *	@gfp_mask:	flags for the page level allocator
+ *	@prot:		protection mask for the allocated pages
+ *	@vm_flags:	additional vm area flags (e.g. %VM_NO_GUARD)
+ *	@node:		node to use for allocation or NUMA_NO_NODE
+ *	@caller:	caller's return address
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator with @gfp_mask flags.  Map them into contiguous
+ *	kernel virtual space, using a pagetable protection of @prot.
+ */
+void *__vmalloc_node_range(unsigned long size, unsigned long align,
+			unsigned long start, unsigned long end, gfp_t gfp_mask,
+			pgprot_t prot, unsigned long vm_flags, int node,
+			const void *caller)
+{
+	struct vm_struct *area;
+	void *addr;
+	unsigned long real_size = size;
+
+	size = PAGE_ALIGN(size);
+	if (!size || (size >> PAGE_SHIFT) > totalram_pages)
+		goto fail;
+
+	area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNINITIALIZED |
+				vm_flags, start, end, node, gfp_mask, caller);
+	if (!area)
+		goto fail;
+
+	addr = __vmalloc_area_node(area, gfp_mask, prot, node);
+	if (!addr)
+		return NULL;
+
+	/*
+	 * First make sure the mappings are removed from all page-tables
+	 * before they are freed.
+	 */
+	vmalloc_sync_all();
+
+	/*
+	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
+	 * flag. It means that vm_struct is not fully initialized.
+	 * Now, it is fully initialized, so remove this flag here.
+	 */
+	clear_vm_uninitialized_flag(area);
+
+	kmemleak_vmalloc(area, size, gfp_mask);
+
+	return addr;
+
+fail:
+	warn_alloc(gfp_mask, NULL,
+			  "vmalloc: allocation failure: %lu bytes", real_size);
+	return NULL;
+}
+
+/**
+ *	__vmalloc_node  -  allocate virtually contiguous memory
+ *	@size:		allocation size
+ *	@align:		desired alignment
+ *	@gfp_mask:	flags for the page level allocator
+ *	@prot:		protection mask for the allocated pages
+ *	@node:		node to use for allocation or NUMA_NO_NODE
+ *	@caller:	caller's return address
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator with @gfp_mask flags.  Map them into contiguous
+ *	kernel virtual space, using a pagetable protection of @prot.
+ *
+ *	Reclaim modifiers in @gfp_mask - __GFP_NORETRY, __GFP_RETRY_MAYFAIL
+ *	and __GFP_NOFAIL are not supported
+ *
+ *	Any use of gfp flags outside of GFP_KERNEL should be consulted
+ *	with mm people.
+ *
+ */
+static void *__vmalloc_node(unsigned long size, unsigned long align,
+			    gfp_t gfp_mask, pgprot_t prot,
+			    int node, const void *caller)
+{
+	return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
+				gfp_mask, prot, 0, node, caller);
+}
+
+void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
+{
+	return __vmalloc_node(size, 1, gfp_mask, prot, NUMA_NO_NODE,
+				__builtin_return_address(0));
+}
+EXPORT_SYMBOL(__vmalloc);
+
+static inline void *__vmalloc_node_flags(unsigned long size,
+					int node, gfp_t flags)
+{
+	return __vmalloc_node(size, 1, flags, PAGE_KERNEL,
+					node, __builtin_return_address(0));
+}
+
+
+void *__vmalloc_node_flags_caller(unsigned long size, int node, gfp_t flags,
+				  void *caller)
+{
+	return __vmalloc_node(size, 1, flags, PAGE_KERNEL, node, caller);
+}
+
+/**
+ *	vmalloc  -  allocate virtually contiguous memory
+ *	@size:		allocation size
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vmalloc(unsigned long size)
+{
+	return __vmalloc_node_flags(size, NUMA_NO_NODE,
+				    GFP_KERNEL);
+}
+EXPORT_SYMBOL(vmalloc);
+
+/**
+ *	vzalloc - allocate virtually contiguous memory with zero fill
+ *	@size:	allocation size
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *	The memory allocated is set to zero.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vzalloc(unsigned long size)
+{
+	return __vmalloc_node_flags(size, NUMA_NO_NODE,
+				GFP_KERNEL | __GFP_ZERO);
+}
+EXPORT_SYMBOL(vzalloc);
+
+/**
+ * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
+ * @size: allocation size
+ *
+ * The resulting memory area is zeroed so it can be mapped to userspace
+ * without leaking data.
+ */
+void *vmalloc_user(unsigned long size)
+{
+	struct vm_struct *area;
+	void *ret;
+
+	ret = __vmalloc_node(size, SHMLBA,
+			     GFP_KERNEL | __GFP_ZERO,
+			     PAGE_KERNEL, NUMA_NO_NODE,
+			     __builtin_return_address(0));
+	if (ret) {
+		area = find_vm_area(ret);
+		area->flags |= VM_USERMAP;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(vmalloc_user);
+
+/**
+ *	vmalloc_node  -  allocate memory on a specific node
+ *	@size:		allocation size
+ *	@node:		numa node
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into contiguous kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vmalloc_node(unsigned long size, int node)
+{
+	return __vmalloc_node(size, 1, GFP_KERNEL, PAGE_KERNEL,
+					node, __builtin_return_address(0));
+}
+EXPORT_SYMBOL(vmalloc_node);
+
+/**
+ * vzalloc_node - allocate memory on a specific node with zero fill
+ * @size:	allocation size
+ * @node:	numa node
+ *
+ * Allocate enough pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ * The memory allocated is set to zero.
+ *
+ * For tight control over page level allocator and protection flags
+ * use __vmalloc_node() instead.
+ */
+void *vzalloc_node(unsigned long size, int node)
+{
+	return __vmalloc_node_flags(size, node,
+			 GFP_KERNEL | __GFP_ZERO);
+}
+EXPORT_SYMBOL(vzalloc_node);
+
+/**
+ *	vmalloc_exec  -  allocate virtually contiguous, executable memory
+ *	@size:		allocation size
+ *
+ *	Kernel-internal function to allocate enough pages to cover @size
+ *	the page level allocator and map them into contiguous and
+ *	executable kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+
+void *vmalloc_exec(unsigned long size)
+{
+	return __vmalloc_node(size, 1, GFP_KERNEL, PAGE_KERNEL_EXEC,
+			      NUMA_NO_NODE, __builtin_return_address(0));
+}
+
+#if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
+#define GFP_VMALLOC32 (GFP_DMA32 | GFP_KERNEL)
+#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
+#define GFP_VMALLOC32 (GFP_DMA | GFP_KERNEL)
+#else
+/*
+ * 64b systems should always have either DMA or DMA32 zones. For others
+ * GFP_DMA32 should do the right thing and use the normal zone.
+ */
+#define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
+#endif
+
+/**
+ *	vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
+ *	@size:		allocation size
+ *
+ *	Allocate enough 32bit PA addressable pages to cover @size from the
+ *	page level allocator and map them into contiguous kernel virtual space.
+ */
+void *vmalloc_32(unsigned long size)
+{
+	return __vmalloc_node(size, 1, GFP_VMALLOC32, PAGE_KERNEL,
+			      NUMA_NO_NODE, __builtin_return_address(0));
+}
+EXPORT_SYMBOL(vmalloc_32);
+
+/**
+ * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
+ *	@size:		allocation size
+ *
+ * The resulting memory area is 32bit addressable and zeroed so it can be
+ * mapped to userspace without leaking data.
+ */
+void *vmalloc_32_user(unsigned long size)
+{
+	struct vm_struct *area;
+	void *ret;
+
+	ret = __vmalloc_node(size, 1, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,
+			     NUMA_NO_NODE, __builtin_return_address(0));
+	if (ret) {
+		area = find_vm_area(ret);
+		area->flags |= VM_USERMAP;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(vmalloc_32_user);
+
+/*
+ * small helper routine , copy contents to buf from addr.
+ * If the page is not present, fill zero.
+ */
+
+static int aligned_vread(char *buf, char *addr, unsigned long count)
+{
+	struct page *p;
+	int copied = 0;
+
+	while (count) {
+		unsigned long offset, length;
+
+		offset = offset_in_page(addr);
+		length = PAGE_SIZE - offset;
+		if (length > count)
+			length = count;
+		p = vmalloc_to_page(addr);
+		/*
+		 * To do safe access to this _mapped_ area, we need
+		 * lock. But adding lock here means that we need to add
+		 * overhead of vmalloc()/vfree() calles for this _debug_
+		 * interface, rarely used. Instead of that, we'll use
+		 * kmap() and get small overhead in this access function.
+		 */
+		if (p) {
+			/*
+			 * we can expect USER0 is not used (see vread/vwrite's
+			 * function description)
+			 */
+			void *map = kmap_atomic(p);
+			memcpy(buf, map + offset, length);
+			kunmap_atomic(map);
+		} else
+			memset(buf, 0, length);
+
+		addr += length;
+		buf += length;
+		copied += length;
+		count -= length;
+	}
+	return copied;
+}
+
+static int aligned_vwrite(char *buf, char *addr, unsigned long count)
+{
+	struct page *p;
+	int copied = 0;
+
+	while (count) {
+		unsigned long offset, length;
+
+		offset = offset_in_page(addr);
+		length = PAGE_SIZE - offset;
+		if (length > count)
+			length = count;
+		p = vmalloc_to_page(addr);
+		/*
+		 * To do safe access to this _mapped_ area, we need
+		 * lock. But adding lock here means that we need to add
+		 * overhead of vmalloc()/vfree() calles for this _debug_
+		 * interface, rarely used. Instead of that, we'll use
+		 * kmap() and get small overhead in this access function.
+		 */
+		if (p) {
+			/*
+			 * we can expect USER0 is not used (see vread/vwrite's
+			 * function description)
+			 */
+			void *map = kmap_atomic(p);
+			memcpy(map + offset, buf, length);
+			kunmap_atomic(map);
+		}
+		addr += length;
+		buf += length;
+		copied += length;
+		count -= length;
+	}
+	return copied;
+}
+
+/**
+ *	vread() -  read vmalloc area in a safe way.
+ *	@buf:		buffer for reading data
+ *	@addr:		vm address.
+ *	@count:		number of bytes to be read.
+ *
+ *	Returns # of bytes which addr and buf should be increased.
+ *	(same number to @count). Returns 0 if [addr...addr+count) doesn't
+ *	includes any intersect with alive vmalloc area.
+ *
+ *	This function checks that addr is a valid vmalloc'ed area, and
+ *	copy data from that area to a given buffer. If the given memory range
+ *	of [addr...addr+count) includes some valid address, data is copied to
+ *	proper area of @buf. If there are memory holes, they'll be zero-filled.
+ *	IOREMAP area is treated as memory hole and no copy is done.
+ *
+ *	If [addr...addr+count) doesn't includes any intersects with alive
+ *	vm_struct area, returns 0. @buf should be kernel's buffer.
+ *
+ *	Note: In usual ops, vread() is never necessary because the caller
+ *	should know vmalloc() area is valid and can use memcpy().
+ *	This is for routines which have to access vmalloc area without
+ *	any informaion, as /dev/kmem.
+ *
+ */
+
+long vread(char *buf, char *addr, unsigned long count)
+{
+	struct vmap_area *va;
+	struct vm_struct *vm;
+	char *vaddr, *buf_start = buf;
+	unsigned long buflen = count;
+	unsigned long n;
+
+	/* Don't allow overflow */
+	if ((unsigned long) addr + count < count)
+		count = -(unsigned long) addr;
+
+	spin_lock(&vmap_area_lock);
+	list_for_each_entry(va, &vmap_area_list, list) {
+		if (!count)
+			break;
+
+		if (!(va->flags & VM_VM_AREA))
+			continue;
+
+		vm = va->vm;
+		vaddr = (char *) vm->addr;
+		if (addr >= vaddr + get_vm_area_size(vm))
+			continue;
+		while (addr < vaddr) {
+			if (count == 0)
+				goto finished;
+			*buf = '\0';
+			buf++;
+			addr++;
+			count--;
+		}
+		n = vaddr + get_vm_area_size(vm) - addr;
+		if (n > count)
+			n = count;
+		if (!(vm->flags & VM_IOREMAP))
+			aligned_vread(buf, addr, n);
+		else /* IOREMAP area is treated as memory hole */
+			memset(buf, 0, n);
+		buf += n;
+		addr += n;
+		count -= n;
+	}
+finished:
+	spin_unlock(&vmap_area_lock);
+
+	if (buf == buf_start)
+		return 0;
+	/* zero-fill memory holes */
+	if (buf != buf_start + buflen)
+		memset(buf, 0, buflen - (buf - buf_start));
+
+	return buflen;
+}
+
+/**
+ *	vwrite() -  write vmalloc area in a safe way.
+ *	@buf:		buffer for source data
+ *	@addr:		vm address.
+ *	@count:		number of bytes to be read.
+ *
+ *	Returns # of bytes which addr and buf should be incresed.
+ *	(same number to @count).
+ *	If [addr...addr+count) doesn't includes any intersect with valid
+ *	vmalloc area, returns 0.
+ *
+ *	This function checks that addr is a valid vmalloc'ed area, and
+ *	copy data from a buffer to the given addr. If specified range of
+ *	[addr...addr+count) includes some valid address, data is copied from
+ *	proper area of @buf. If there are memory holes, no copy to hole.
+ *	IOREMAP area is treated as memory hole and no copy is done.
+ *
+ *	If [addr...addr+count) doesn't includes any intersects with alive
+ *	vm_struct area, returns 0. @buf should be kernel's buffer.
+ *
+ *	Note: In usual ops, vwrite() is never necessary because the caller
+ *	should know vmalloc() area is valid and can use memcpy().
+ *	This is for routines which have to access vmalloc area without
+ *	any informaion, as /dev/kmem.
+ */
+
+long vwrite(char *buf, char *addr, unsigned long count)
+{
+	struct vmap_area *va;
+	struct vm_struct *vm;
+	char *vaddr;
+	unsigned long n, buflen;
+	int copied = 0;
+
+	/* Don't allow overflow */
+	if ((unsigned long) addr + count < count)
+		count = -(unsigned long) addr;
+	buflen = count;
+
+	spin_lock(&vmap_area_lock);
+	list_for_each_entry(va, &vmap_area_list, list) {
+		if (!count)
+			break;
+
+		if (!(va->flags & VM_VM_AREA))
+			continue;
+
+		vm = va->vm;
+		vaddr = (char *) vm->addr;
+		if (addr >= vaddr + get_vm_area_size(vm))
+			continue;
+		while (addr < vaddr) {
+			if (count == 0)
+				goto finished;
+			buf++;
+			addr++;
+			count--;
+		}
+		n = vaddr + get_vm_area_size(vm) - addr;
+		if (n > count)
+			n = count;
+		if (!(vm->flags & VM_IOREMAP)) {
+			aligned_vwrite(buf, addr, n);
+			copied++;
+		}
+		buf += n;
+		addr += n;
+		count -= n;
+	}
+finished:
+	spin_unlock(&vmap_area_lock);
+	if (!copied)
+		return 0;
+	return buflen;
+}
+
+/**
+ *	remap_vmalloc_range_partial  -  map vmalloc pages to userspace
+ *	@vma:		vma to cover
+ *	@uaddr:		target user address to start at
+ *	@kaddr:		virtual address of vmalloc kernel memory
+ *	@size:		size of map area
+ *
+ *	Returns:	0 for success, -Exxx on failure
+ *
+ *	This function checks that @kaddr is a valid vmalloc'ed area,
+ *	and that it is big enough to cover the range starting at
+ *	@uaddr in @vma. Will return failure if that criteria isn't
+ *	met.
+ *
+ *	Similar to remap_pfn_range() (see mm/memory.c)
+ */
+int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
+				void *kaddr, unsigned long size)
+{
+	struct vm_struct *area;
+
+	size = PAGE_ALIGN(size);
+
+	if (!PAGE_ALIGNED(uaddr) || !PAGE_ALIGNED(kaddr))
+		return -EINVAL;
+
+	area = find_vm_area(kaddr);
+	if (!area)
+		return -EINVAL;
+
+	if (!(area->flags & VM_USERMAP))
+		return -EINVAL;
+
+	if (kaddr + size > area->addr + get_vm_area_size(area))
+		return -EINVAL;
+
+	do {
+		struct page *page = vmalloc_to_page(kaddr);
+		int ret;
+
+		ret = vm_insert_page(vma, uaddr, page);
+		if (ret)
+			return ret;
+
+		uaddr += PAGE_SIZE;
+		kaddr += PAGE_SIZE;
+		size -= PAGE_SIZE;
+	} while (size > 0);
+
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+
+	return 0;
+}
+EXPORT_SYMBOL(remap_vmalloc_range_partial);
+
+/**
+ *	remap_vmalloc_range  -  map vmalloc pages to userspace
+ *	@vma:		vma to cover (map full range of vma)
+ *	@addr:		vmalloc memory
+ *	@pgoff:		number of pages into addr before first page to map
+ *
+ *	Returns:	0 for success, -Exxx on failure
+ *
+ *	This function checks that addr is a valid vmalloc'ed area, and
+ *	that it is big enough to cover the vma. Will return failure if
+ *	that criteria isn't met.
+ *
+ *	Similar to remap_pfn_range() (see mm/memory.c)
+ */
+int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
+						unsigned long pgoff)
+{
+	return remap_vmalloc_range_partial(vma, vma->vm_start,
+					   addr + (pgoff << PAGE_SHIFT),
+					   vma->vm_end - vma->vm_start);
+}
+EXPORT_SYMBOL(remap_vmalloc_range);
+
+/*
+ * Implement a stub for vmalloc_sync_all() if the architecture chose not to
+ * have one.
+ *
+ * The purpose of this function is to make sure the vmalloc area
+ * mappings are identical in all page-tables in the system.
+ */
+void __weak vmalloc_sync_all(void)
+{
+}
+
+
+static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
+{
+	pte_t ***p = data;
+
+	if (p) {
+		*(*p) = pte;
+		(*p)++;
+	}
+	return 0;
+}
+
+/**
+ *	alloc_vm_area - allocate a range of kernel address space
+ *	@size:		size of the area
+ *	@ptes:		returns the PTEs for the address space
+ *
+ *	Returns:	NULL on failure, vm_struct on success
+ *
+ *	This function reserves a range of kernel address space, and
+ *	allocates pagetables to map that range.  No actual mappings
+ *	are created.
+ *
+ *	If @ptes is non-NULL, pointers to the PTEs (in init_mm)
+ *	allocated for the VM area are returned.
+ */
+struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
+{
+	struct vm_struct *area;
+
+	area = get_vm_area_caller(size, VM_IOREMAP,
+				__builtin_return_address(0));
+	if (area == NULL)
+		return NULL;
+
+	/*
+	 * This ensures that page tables are constructed for this region
+	 * of kernel virtual address space and mapped into init_mm.
+	 */
+	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
+				size, f, ptes ? &ptes : NULL)) {
+		free_vm_area(area);
+		return NULL;
+	}
+
+	return area;
+}
+EXPORT_SYMBOL_GPL(alloc_vm_area);
+
+void free_vm_area(struct vm_struct *area)
+{
+	struct vm_struct *ret;
+	ret = remove_vm_area(area->addr);
+	BUG_ON(ret != area);
+	kfree(area);
+}
+EXPORT_SYMBOL_GPL(free_vm_area);
+
+#ifdef CONFIG_SMP
+static struct vmap_area *node_to_va(struct rb_node *n)
+{
+	return rb_entry_safe(n, struct vmap_area, rb_node);
+}
+
+/**
+ * pvm_find_next_prev - find the next and prev vmap_area surrounding @end
+ * @end: target address
+ * @pnext: out arg for the next vmap_area
+ * @pprev: out arg for the previous vmap_area
+ *
+ * Returns: %true if either or both of next and prev are found,
+ *	    %false if no vmap_area exists
+ *
+ * Find vmap_areas end addresses of which enclose @end.  ie. if not
+ * NULL, *pnext->va_end > @end and *pprev->va_end <= @end.
+ */
+static bool pvm_find_next_prev(unsigned long end,
+			       struct vmap_area **pnext,
+			       struct vmap_area **pprev)
+{
+	struct rb_node *n = vmap_area_root.rb_node;
+	struct vmap_area *va = NULL;
+
+	while (n) {
+		va = rb_entry(n, struct vmap_area, rb_node);
+		if (end < va->va_end)
+			n = n->rb_left;
+		else if (end > va->va_end)
+			n = n->rb_right;
+		else
+			break;
+	}
+
+	if (!va)
+		return false;
+
+	if (va->va_end > end) {
+		*pnext = va;
+		*pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+	} else {
+		*pprev = va;
+		*pnext = node_to_va(rb_next(&(*pprev)->rb_node));
+	}
+	return true;
+}
+
+/**
+ * pvm_determine_end - find the highest aligned address between two vmap_areas
+ * @pnext: in/out arg for the next vmap_area
+ * @pprev: in/out arg for the previous vmap_area
+ * @align: alignment
+ *
+ * Returns: determined end address
+ *
+ * Find the highest aligned address between *@pnext and *@pprev below
+ * VMALLOC_END.  *@pnext and *@pprev are adjusted so that the aligned
+ * down address is between the end addresses of the two vmap_areas.
+ *
+ * Please note that the address returned by this function may fall
+ * inside *@pnext vmap_area.  The caller is responsible for checking
+ * that.
+ */
+static unsigned long pvm_determine_end(struct vmap_area **pnext,
+				       struct vmap_area **pprev,
+				       unsigned long align)
+{
+	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
+	unsigned long addr;
+
+	if (*pnext)
+		addr = min((*pnext)->va_start & ~(align - 1), vmalloc_end);
+	else
+		addr = vmalloc_end;
+
+	while (*pprev && (*pprev)->va_end > addr) {
+		*pnext = *pprev;
+		*pprev = node_to_va(rb_prev(&(*pnext)->rb_node));
+	}
+
+	return addr;
+}
+
+/**
+ * pcpu_get_vm_areas - allocate vmalloc areas for percpu allocator
+ * @offsets: array containing offset of each area
+ * @sizes: array containing size of each area
+ * @nr_vms: the number of areas to allocate
+ * @align: alignment, all entries in @offsets and @sizes must be aligned to this
+ *
+ * Returns: kmalloc'd vm_struct pointer array pointing to allocated
+ *	    vm_structs on success, %NULL on failure
+ *
+ * Percpu allocator wants to use congruent vm areas so that it can
+ * maintain the offsets among percpu areas.  This function allocates
+ * congruent vmalloc areas for it with GFP_KERNEL.  These areas tend to
+ * be scattered pretty far, distance between two areas easily going up
+ * to gigabytes.  To avoid interacting with regular vmallocs, these
+ * areas are allocated from top.
+ *
+ * Despite its complicated look, this allocator is rather simple.  It
+ * does everything top-down and scans areas from the end looking for
+ * matching slot.  While scanning, if any of the areas overlaps with
+ * existing vmap_area, the base address is pulled down to fit the
+ * area.  Scanning is repeated till all the areas fit and then all
+ * necessary data structures are inserted and the result is returned.
+ */
+struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
+				     const size_t *sizes, int nr_vms,
+				     size_t align)
+{
+	const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
+	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
+	struct vmap_area **vas, *prev, *next;
+	struct vm_struct **vms;
+	int area, area2, last_area, term_area;
+	unsigned long base, start, end, last_end;
+	bool purged = false;
+
+	/* verify parameters and allocate data structures */
+	BUG_ON(offset_in_page(align) || !is_power_of_2(align));
+	for (last_area = 0, area = 0; area < nr_vms; area++) {
+		start = offsets[area];
+		end = start + sizes[area];
+
+		/* is everything aligned properly? */
+		BUG_ON(!IS_ALIGNED(offsets[area], align));
+		BUG_ON(!IS_ALIGNED(sizes[area], align));
+
+		/* detect the area with the highest address */
+		if (start > offsets[last_area])
+			last_area = area;
+
+		for (area2 = area + 1; area2 < nr_vms; area2++) {
+			unsigned long start2 = offsets[area2];
+			unsigned long end2 = start2 + sizes[area2];
+
+			BUG_ON(start2 < end && start < end2);
+		}
+	}
+	last_end = offsets[last_area] + sizes[last_area];
+
+	if (vmalloc_end - vmalloc_start < last_end) {
+		WARN_ON(true);
+		return NULL;
+	}
+
+	vms = kcalloc(nr_vms, sizeof(vms[0]), GFP_KERNEL);
+	vas = kcalloc(nr_vms, sizeof(vas[0]), GFP_KERNEL);
+	if (!vas || !vms)
+		goto err_free2;
+
+	for (area = 0; area < nr_vms; area++) {
+		vas[area] = kzalloc(sizeof(struct vmap_area), GFP_KERNEL);
+		vms[area] = kzalloc(sizeof(struct vm_struct), GFP_KERNEL);
+		if (!vas[area] || !vms[area])
+			goto err_free;
+	}
+retry:
+	spin_lock(&vmap_area_lock);
+
+	/* start scanning - we scan from the top, begin with the last area */
+	area = term_area = last_area;
+	start = offsets[area];
+	end = start + sizes[area];
+
+	if (!pvm_find_next_prev(vmap_area_pcpu_hole, &next, &prev)) {
+		base = vmalloc_end - last_end;
+		goto found;
+	}
+	base = pvm_determine_end(&next, &prev, align) - end;
+
+	while (true) {
+		BUG_ON(next && next->va_end <= base + end);
+		BUG_ON(prev && prev->va_end > base + end);
+
+		/*
+		 * base might have underflowed, add last_end before
+		 * comparing.
+		 */
+		if (base + last_end < vmalloc_start + last_end) {
+			spin_unlock(&vmap_area_lock);
+			if (!purged) {
+				purge_vmap_area_lazy();
+				purged = true;
+				goto retry;
+			}
+			goto err_free;
+		}
+
+		/*
+		 * If next overlaps, move base downwards so that it's
+		 * right below next and then recheck.
+		 */
+		if (next && next->va_start < base + end) {
+			base = pvm_determine_end(&next, &prev, align) - end;
+			term_area = area;
+			continue;
+		}
+
+		/*
+		 * If prev overlaps, shift down next and prev and move
+		 * base so that it's right below new next and then
+		 * recheck.
+		 */
+		if (prev && prev->va_end > base + start)  {
+			next = prev;
+			prev = node_to_va(rb_prev(&next->rb_node));
+			base = pvm_determine_end(&next, &prev, align) - end;
+			term_area = area;
+			continue;
+		}
+
+		/*
+		 * This area fits, move on to the previous one.  If
+		 * the previous one is the terminal one, we're done.
+		 */
+		area = (area + nr_vms - 1) % nr_vms;
+		if (area == term_area)
+			break;
+		start = offsets[area];
+		end = start + sizes[area];
+		pvm_find_next_prev(base + end, &next, &prev);
+	}
+found:
+	/* we've found a fitting base, insert all va's */
+	for (area = 0; area < nr_vms; area++) {
+		struct vmap_area *va = vas[area];
+
+		va->va_start = base + offsets[area];
+		va->va_end = va->va_start + sizes[area];
+		__insert_vmap_area(va);
+	}
+
+	vmap_area_pcpu_hole = base + offsets[last_area];
+
+	spin_unlock(&vmap_area_lock);
+
+	/* insert all vm's */
+	for (area = 0; area < nr_vms; area++)
+		setup_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
+				 pcpu_get_vm_areas);
+
+	kfree(vas);
+	return vms;
+
+err_free:
+	for (area = 0; area < nr_vms; area++) {
+		kfree(vas[area]);
+		kfree(vms[area]);
+	}
+err_free2:
+	kfree(vas);
+	kfree(vms);
+	return NULL;
+}
+
+/**
+ * pcpu_free_vm_areas - free vmalloc areas for percpu allocator
+ * @vms: vm_struct pointer array returned by pcpu_get_vm_areas()
+ * @nr_vms: the number of allocated areas
+ *
+ * Free vm_structs and the array allocated by pcpu_get_vm_areas().
+ */
+void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
+{
+	int i;
+
+	for (i = 0; i < nr_vms; i++)
+		free_vm_area(vms[i]);
+	kfree(vms);
+}
+#endif	/* CONFIG_SMP */
+
+#ifdef CONFIG_PROC_FS
+static void *s_start(struct seq_file *m, loff_t *pos)
+	__acquires(&vmap_area_lock)
+{
+	spin_lock(&vmap_area_lock);
+	return seq_list_start(&vmap_area_list, *pos);
+}
+
+static void *s_next(struct seq_file *m, void *p, loff_t *pos)
+{
+	return seq_list_next(p, &vmap_area_list, pos);
+}
+
+static void s_stop(struct seq_file *m, void *p)
+	__releases(&vmap_area_lock)
+{
+	spin_unlock(&vmap_area_lock);
+}
+
+static void show_numa_info(struct seq_file *m, struct vm_struct *v)
+{
+	if (IS_ENABLED(CONFIG_NUMA)) {
+		unsigned int nr, *counters = m->private;
+
+		if (!counters)
+			return;
+
+		if (v->flags & VM_UNINITIALIZED)
+			return;
+		/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
+		smp_rmb();
+
+		memset(counters, 0, nr_node_ids * sizeof(unsigned int));
+
+		for (nr = 0; nr < v->nr_pages; nr++)
+			counters[page_to_nid(v->pages[nr])]++;
+
+		for_each_node_state(nr, N_HIGH_MEMORY)
+			if (counters[nr])
+				seq_printf(m, " N%u=%u", nr, counters[nr]);
+	}
+}
+
+static int s_show(struct seq_file *m, void *p)
+{
+	struct vmap_area *va;
+	struct vm_struct *v;
+
+	va = list_entry(p, struct vmap_area, list);
+
+	/*
+	 * s_show can encounter race with remove_vm_area, !VM_VM_AREA on
+	 * behalf of vmap area is being tear down or vm_map_ram allocation.
+	 */
+	if (!(va->flags & VM_VM_AREA)) {
+		seq_printf(m, "0x%pK-0x%pK %7ld %s\n",
+			(void *)va->va_start, (void *)va->va_end,
+			va->va_end - va->va_start,
+			va->flags & VM_LAZY_FREE ? "unpurged vm_area" : "vm_map_ram");
+
+		return 0;
+	}
+
+	v = va->vm;
+
+	seq_printf(m, "0x%pK-0x%pK %7ld",
+		v->addr, v->addr + v->size, v->size);
+
+	if (v->caller)
+		seq_printf(m, " %pS", v->caller);
+
+	if (v->nr_pages)
+		seq_printf(m, " pages=%d", v->nr_pages);
+
+	if (v->phys_addr)
+		seq_printf(m, " phys=%pa", &v->phys_addr);
+
+	if (v->flags & VM_IOREMAP)
+		seq_puts(m, " ioremap");
+
+	if (v->flags & VM_ALLOC)
+		seq_puts(m, " vmalloc");
+
+	if (v->flags & VM_MAP)
+		seq_puts(m, " vmap");
+
+	if (v->flags & VM_USERMAP)
+		seq_puts(m, " user");
+
+	if (is_vmalloc_addr(v->pages))
+		seq_puts(m, " vpages");
+
+	show_numa_info(m, v);
+	seq_putc(m, '\n');
+	return 0;
+}
+
+static const struct seq_operations vmalloc_op = {
+	.start = s_start,
+	.next = s_next,
+	.stop = s_stop,
+	.show = s_show,
+};
+
+static int __init proc_vmalloc_init(void)
+{
+	if (IS_ENABLED(CONFIG_PROC_STRIPPED))
+		return 0;
+	if (IS_ENABLED(CONFIG_NUMA))
+		proc_create_seq_private("vmallocinfo", 0400, NULL,
+				&vmalloc_op,
+				nr_node_ids * sizeof(unsigned int), NULL);
+	else
+		proc_create_seq("vmallocinfo", 0400, NULL, &vmalloc_op);
+	return 0;
+}
+module_init(proc_vmalloc_init);
+
+#endif
+