* the type/offset into the pte as 5/27 as well.
*/
#define MAX_SWAPFILES_SHIFT 5
+#ifndef CONFIG_MIGRATION
#define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT)
+#else
+/* Use last two entries for page migration swap entries */
+#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT)-2)
+#define SWP_MIGRATION_READ MAX_SWAPFILES
+#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + 1)
+#endif
/*
* Magic header for a swap area. The first part of the union is
BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
return __swp_entry_to_pte(arch_entry);
}
+
+#ifdef CONFIG_MIGRATION
+static inline swp_entry_t make_migration_entry(struct page *page, int write)
+{
+ BUG_ON(!PageLocked(page));
+ return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
+ page_to_pfn(page));
+}
+
+static inline int is_migration_entry(swp_entry_t entry)
+{
+ return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
+ swp_type(entry) == SWP_MIGRATION_WRITE);
+}
+
+static inline int is_write_migration_entry(swp_entry_t entry)
+{
+ return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
+}
+
+static inline struct page *migration_entry_to_page(swp_entry_t entry)
+{
+ struct page *p = pfn_to_page(swp_offset(entry));
+ /*
+ * Any use of migration entries may only occur while the
+ * corresponding page is locked
+ */
+ BUG_ON(!PageLocked(p));
+ return p;
+}
+
+static inline void make_migration_entry_read(swp_entry_t *entry)
+{
+ *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
+}
+
+extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address);
+#else
+
+#define make_migration_entry(page, write) swp_entry(0, 0)
+#define is_migration_entry(swp) 0
+#define migration_entry_to_page(swp) NULL
+static inline void make_migration_entry_read(swp_entry_t *entryp) { }
+static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address) { }
+static inline int is_write_migration_entry(swp_entry_t entry)
+{
+ return 0;
+}
+
+#endif
+
/* pte contains position in swap or file, so copy. */
if (unlikely(!pte_present(pte))) {
if (!pte_file(pte)) {
- swap_duplicate(pte_to_swp_entry(pte));
+ swp_entry_t entry = pte_to_swp_entry(pte);
+
+ swap_duplicate(entry);
/* make sure dst_mm is on swapoff's mmlist. */
if (unlikely(list_empty(&dst_mm->mmlist))) {
spin_lock(&mmlist_lock);
&src_mm->mmlist);
spin_unlock(&mmlist_lock);
}
+ if (is_write_migration_entry(entry) &&
+ is_cow_mapping(vm_flags)) {
+ /*
+ * COW mappings require pages in both parent
+ * and child to be set to read.
+ */
+ make_migration_entry_read(&entry);
+ pte = swp_entry_to_pte(entry);
+ set_pte_at(src_mm, addr, src_pte, pte);
+ }
}
goto out_set_pte;
}
goto out;
entry = pte_to_swp_entry(orig_pte);
+ if (is_migration_entry(entry)) {
+ migration_entry_wait(mm, pmd, address);
+ goto out;
+ }
page = lookup_swap_cache(entry);
if (!page) {
swapin_readahead(entry, address, vma);
#include <linux/migrate.h>
#include <linux/module.h>
#include <linux/swap.h>
+#include <linux/swapops.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include <linux/mm_inline.h>
#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
-#include <linux/swapops.h>
#include "internal.h"
return count;
}
+static inline int is_swap_pte(pte_t pte)
+{
+ return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
+}
+
+/*
+ * Restore a potential migration pte to a working pte entry
+ */
+static void remove_migration_pte(struct vm_area_struct *vma, unsigned long addr,
+ struct page *old, struct page *new)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ swp_entry_t entry;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+
+ pgd = pgd_offset(mm, addr);
+ if (!pgd_present(*pgd))
+ return;
+
+ pud = pud_offset(pgd, addr);
+ if (!pud_present(*pud))
+ return;
+
+ pmd = pmd_offset(pud, addr);
+ if (!pmd_present(*pmd))
+ return;
+
+ ptep = pte_offset_map(pmd, addr);
+
+ if (!is_swap_pte(*ptep)) {
+ pte_unmap(ptep);
+ return;
+ }
+
+ ptl = pte_lockptr(mm, pmd);
+ spin_lock(ptl);
+ pte = *ptep;
+ if (!is_swap_pte(pte))
+ goto out;
+
+ entry = pte_to_swp_entry(pte);
+
+ if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
+ goto out;
+
+ inc_mm_counter(mm, anon_rss);
+ get_page(new);
+ pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
+ if (is_write_migration_entry(entry))
+ pte = pte_mkwrite(pte);
+ set_pte_at(mm, addr, ptep, pte);
+ page_add_anon_rmap(new, vma, addr);
+out:
+ pte_unmap_unlock(ptep, ptl);
+}
+
+/*
+ * Get rid of all migration entries and replace them by
+ * references to the indicated page.
+ *
+ * Must hold mmap_sem lock on at least one of the vmas containing
+ * the page so that the anon_vma cannot vanish.
+ */
+static void remove_migration_ptes(struct page *old, struct page *new)
+{
+ struct anon_vma *anon_vma;
+ struct vm_area_struct *vma;
+ unsigned long mapping;
+
+ mapping = (unsigned long)new->mapping;
+
+ if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
+ return;
+
+ /*
+ * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
+ */
+ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
+ spin_lock(&anon_vma->lock);
+
+ list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
+ remove_migration_pte(vma, page_address_in_vma(new, vma),
+ old, new);
+
+ spin_unlock(&anon_vma->lock);
+}
+
+/*
+ * Something used the pte of a page under migration. We need to
+ * get to the page and wait until migration is finished.
+ * When we return from this function the fault will be retried.
+ *
+ * This function is called from do_swap_page().
+ */
+void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address)
+{
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+ swp_entry_t entry;
+ struct page *page;
+
+ ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+ pte = *ptep;
+ if (!is_swap_pte(pte))
+ goto out;
+
+ entry = pte_to_swp_entry(pte);
+ if (!is_migration_entry(entry))
+ goto out;
+
+ page = migration_entry_to_page(entry);
+
+ get_page(page);
+ pte_unmap_unlock(ptep, ptl);
+ wait_on_page_locked(page);
+ put_page(page);
+ return;
+out:
+ pte_unmap_unlock(ptep, ptl);
+}
+
/*
* swapout a single page
* page is locked upon entry, unlocked on exit
#include <linux/mempolicy.h>
#include <linux/personality.h>
#include <linux/syscalls.h>
-
+#include <linux/swap.h>
+#include <linux/swapops.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot)
{
- pte_t *pte;
+ pte_t *pte, oldpte;
spinlock_t *ptl;
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
do {
- if (pte_present(*pte)) {
+ oldpte = *pte;
+ if (pte_present(oldpte)) {
pte_t ptent;
/* Avoid an SMP race with hardware updated dirty/clean
ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot);
set_pte_at(mm, addr, pte, ptent);
lazy_mmu_prot_update(ptent);
+#ifdef CONFIG_MIGRATION
+ } else if (!pte_file(oldpte)) {
+ swp_entry_t entry = pte_to_swp_entry(oldpte);
+
+ if (is_write_migration_entry(entry)) {
+ /*
+ * A protection check is difficult so
+ * just be safe and disable write
+ */
+ make_migration_entry_read(&entry);
+ set_pte_at(mm, addr, pte,
+ swp_entry_to_pte(entry));
+ }
+#endif
}
+
} while (pte++, addr += PAGE_SIZE, addr != end);
pte_unmap_unlock(pte - 1, ptl);
}
spin_lock(&mm->page_table_lock);
if (likely(!vma->anon_vma)) {
vma->anon_vma = anon_vma;
- list_add(&vma->anon_vma_node, &anon_vma->head);
+ list_add_tail(&vma->anon_vma_node, &anon_vma->head);
allocated = NULL;
}
spin_unlock(&mm->page_table_lock);
struct anon_vma *anon_vma = vma->anon_vma;
if (anon_vma) {
- list_add(&vma->anon_vma_node, &anon_vma->head);
+ list_add_tail(&vma->anon_vma_node, &anon_vma->head);
validate_anon_vma(vma);
}
}
if (anon_vma) {
spin_lock(&anon_vma->lock);
- list_add(&vma->anon_vma_node, &anon_vma->head);
+ list_add_tail(&vma->anon_vma_node, &anon_vma->head);
validate_anon_vma(vma);
spin_unlock(&anon_vma->lock);
}
if (PageAnon(page)) {
swp_entry_t entry = { .val = page_private(page) };
- /*
- * Store the swap location in the pte.
- * See handle_pte_fault() ...
- */
- BUG_ON(!PageSwapCache(page));
- swap_duplicate(entry);
- if (list_empty(&mm->mmlist)) {
- spin_lock(&mmlist_lock);
- if (list_empty(&mm->mmlist))
- list_add(&mm->mmlist, &init_mm.mmlist);
- spin_unlock(&mmlist_lock);
+
+ if (PageSwapCache(page)) {
+ /*
+ * Store the swap location in the pte.
+ * See handle_pte_fault() ...
+ */
+ swap_duplicate(entry);
+ if (list_empty(&mm->mmlist)) {
+ spin_lock(&mmlist_lock);
+ if (list_empty(&mm->mmlist))
+ list_add(&mm->mmlist, &init_mm.mmlist);
+ spin_unlock(&mmlist_lock);
+ }
+ } else {
+ /*
+ * Store the pfn of the page in a special migration
+ * pte. do_swap_page() will wait until the migration
+ * pte is removed and then restart fault handling.
+ */
+ BUG_ON(!migration);
+ entry = make_migration_entry(page, pte_write(pteval));
}
set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
BUG_ON(pte_file(*pte));
struct swap_info_struct * p;
struct page *page = NULL;
+ if (is_migration_entry(entry))
+ return;
+
p = swap_info_get(entry);
if (p) {
if (swap_entry_free(p, swp_offset(entry)) == 1) {
if (!(p->flags & SWP_USED))
break;
error = -EPERM;
- /*
- * Test if adding another swap device is possible. There are
- * two limiting factors: 1) the number of bits for the swap
- * type swp_entry_t definition and 2) the number of bits for
- * the swap type in the swap ptes as defined by the different
- * architectures. To honor both limitations a swap entry
- * with swap offset 0 and swap type ~0UL is created, encoded
- * to a swap pte, decoded to a swp_entry_t again and finally
- * the swap type part is extracted. This will mask all bits
- * from the initial ~0UL that can't be encoded in either the
- * swp_entry_t or the architecture definition of a swap pte.
- */
- if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
+ if (type >= MAX_SWAPFILES) {
spin_unlock(&swap_lock);
goto out;
}
unsigned long offset, type;
int result = 0;
+ if (is_migration_entry(entry))
+ return 1;
+
type = swp_type(entry);
if (type >= nr_swapfiles)
goto bad_file;
projects / users / willy / pagecache.git / commitdiff