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-rw-r--r--mm/rmap.c185
1 files changed, 148 insertions, 37 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 278cd277bde..fcd593c9c99 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -62,6 +62,7 @@
#include "internal.h"
static struct kmem_cache *anon_vma_cachep;
+static struct kmem_cache *anon_vma_chain_cachep;
static inline struct anon_vma *anon_vma_alloc(void)
{
@@ -73,6 +74,16 @@ void anon_vma_free(struct anon_vma *anon_vma)
kmem_cache_free(anon_vma_cachep, anon_vma);
}
+static inline struct anon_vma_chain *anon_vma_chain_alloc(void)
+{
+ return kmem_cache_alloc(anon_vma_chain_cachep, GFP_KERNEL);
+}
+
+void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
+{
+ kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
+}
+
/**
* anon_vma_prepare - attach an anon_vma to a memory region
* @vma: the memory region in question
@@ -103,18 +114,23 @@ void anon_vma_free(struct anon_vma *anon_vma)
int anon_vma_prepare(struct vm_area_struct *vma)
{
struct anon_vma *anon_vma = vma->anon_vma;
+ struct anon_vma_chain *avc;
might_sleep();
if (unlikely(!anon_vma)) {
struct mm_struct *mm = vma->vm_mm;
struct anon_vma *allocated;
+ avc = anon_vma_chain_alloc();
+ if (!avc)
+ goto out_enomem;
+
anon_vma = find_mergeable_anon_vma(vma);
allocated = NULL;
if (!anon_vma) {
anon_vma = anon_vma_alloc();
if (unlikely(!anon_vma))
- return -ENOMEM;
+ goto out_enomem_free_avc;
allocated = anon_vma;
}
spin_lock(&anon_vma->lock);
@@ -123,53 +139,113 @@ int anon_vma_prepare(struct vm_area_struct *vma)
spin_lock(&mm->page_table_lock);
if (likely(!vma->anon_vma)) {
vma->anon_vma = anon_vma;
- list_add_tail(&vma->anon_vma_node, &anon_vma->head);
+ avc->anon_vma = anon_vma;
+ avc->vma = vma;
+ list_add(&avc->same_vma, &vma->anon_vma_chain);
+ list_add(&avc->same_anon_vma, &anon_vma->head);
allocated = NULL;
}
spin_unlock(&mm->page_table_lock);
spin_unlock(&anon_vma->lock);
- if (unlikely(allocated))
+ if (unlikely(allocated)) {
anon_vma_free(allocated);
+ anon_vma_chain_free(avc);
+ }
}
return 0;
+
+ out_enomem_free_avc:
+ anon_vma_chain_free(avc);
+ out_enomem:
+ return -ENOMEM;
}
-void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next)
+static void anon_vma_chain_link(struct vm_area_struct *vma,
+ struct anon_vma_chain *avc,
+ struct anon_vma *anon_vma)
{
- BUG_ON(vma->anon_vma != next->anon_vma);
- list_del(&next->anon_vma_node);
+ avc->vma = vma;
+ avc->anon_vma = anon_vma;
+ list_add(&avc->same_vma, &vma->anon_vma_chain);
+
+ spin_lock(&anon_vma->lock);
+ list_add_tail(&avc->same_anon_vma, &anon_vma->head);
+ spin_unlock(&anon_vma->lock);
}
-void __anon_vma_link(struct vm_area_struct *vma)
+/*
+ * Attach the anon_vmas from src to dst.
+ * Returns 0 on success, -ENOMEM on failure.
+ */
+int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
{
- struct anon_vma *anon_vma = vma->anon_vma;
+ struct anon_vma_chain *avc, *pavc;
- if (anon_vma)
- list_add_tail(&vma->anon_vma_node, &anon_vma->head);
+ list_for_each_entry(pavc, &src->anon_vma_chain, same_vma) {
+ avc = anon_vma_chain_alloc();
+ if (!avc)
+ goto enomem_failure;
+ anon_vma_chain_link(dst, avc, pavc->anon_vma);
+ }
+ return 0;
+
+ enomem_failure:
+ unlink_anon_vmas(dst);
+ return -ENOMEM;
}
-void anon_vma_link(struct vm_area_struct *vma)
+/*
+ * Attach vma to its own anon_vma, as well as to the anon_vmas that
+ * the corresponding VMA in the parent process is attached to.
+ * Returns 0 on success, non-zero on failure.
+ */
+int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
{
- struct anon_vma *anon_vma = vma->anon_vma;
+ struct anon_vma_chain *avc;
+ struct anon_vma *anon_vma;
- if (anon_vma) {
- spin_lock(&anon_vma->lock);
- list_add_tail(&vma->anon_vma_node, &anon_vma->head);
- spin_unlock(&anon_vma->lock);
- }
+ /* Don't bother if the parent process has no anon_vma here. */
+ if (!pvma->anon_vma)
+ return 0;
+
+ /*
+ * First, attach the new VMA to the parent VMA's anon_vmas,
+ * so rmap can find non-COWed pages in child processes.
+ */
+ if (anon_vma_clone(vma, pvma))
+ return -ENOMEM;
+
+ /* Then add our own anon_vma. */
+ anon_vma = anon_vma_alloc();
+ if (!anon_vma)
+ goto out_error;
+ avc = anon_vma_chain_alloc();
+ if (!avc)
+ goto out_error_free_anon_vma;
+ anon_vma_chain_link(vma, avc, anon_vma);
+ /* Mark this anon_vma as the one where our new (COWed) pages go. */
+ vma->anon_vma = anon_vma;
+
+ return 0;
+
+ out_error_free_anon_vma:
+ anon_vma_free(anon_vma);
+ out_error:
+ return -ENOMEM;
}
-void anon_vma_unlink(struct vm_area_struct *vma)
+static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain)
{
- struct anon_vma *anon_vma = vma->anon_vma;
+ struct anon_vma *anon_vma = anon_vma_chain->anon_vma;
int empty;
+ /* If anon_vma_fork fails, we can get an empty anon_vma_chain. */
if (!anon_vma)
return;
spin_lock(&anon_vma->lock);
- list_del(&vma->anon_vma_node);
+ list_del(&anon_vma_chain->same_anon_vma);
/* We must garbage collect the anon_vma if it's empty */
empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma);
@@ -179,6 +255,18 @@ void anon_vma_unlink(struct vm_area_struct *vma)
anon_vma_free(anon_vma);
}
+void unlink_anon_vmas(struct vm_area_struct *vma)
+{
+ struct anon_vma_chain *avc, *next;
+
+ /* Unlink each anon_vma chained to the VMA. */
+ list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
+ anon_vma_unlink(avc);
+ list_del(&avc->same_vma);
+ anon_vma_chain_free(avc);
+ }
+}
+
static void anon_vma_ctor(void *data)
{
struct anon_vma *anon_vma = data;
@@ -192,6 +280,7 @@ void __init anon_vma_init(void)
{
anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
+ anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC);
}
/*
@@ -396,7 +485,7 @@ static int page_referenced_anon(struct page *page,
{
unsigned int mapcount;
struct anon_vma *anon_vma;
- struct vm_area_struct *vma;
+ struct anon_vma_chain *avc;
int referenced = 0;
anon_vma = page_lock_anon_vma(page);
@@ -404,7 +493,8 @@ static int page_referenced_anon(struct page *page,
return referenced;
mapcount = page_mapcount(page);
- list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
+ list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
+ struct vm_area_struct *vma = avc->vma;
unsigned long address = vma_address(page, vma);
if (address == -EFAULT)
continue;
@@ -511,9 +601,6 @@ int page_referenced(struct page *page,
int referenced = 0;
int we_locked = 0;
- if (TestClearPageReferenced(page))
- referenced++;
-
*vm_flags = 0;
if (page_mapped(page) && page_rmapping(page)) {
if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
@@ -614,6 +701,30 @@ int page_mkclean(struct page *page)
EXPORT_SYMBOL_GPL(page_mkclean);
/**
+ * page_move_anon_rmap - move a page to our anon_vma
+ * @page: the page to move to our anon_vma
+ * @vma: the vma the page belongs to
+ * @address: the user virtual address mapped
+ *
+ * When a page belongs exclusively to one process after a COW event,
+ * that page can be moved into the anon_vma that belongs to just that
+ * process, so the rmap code will not search the parent or sibling
+ * processes.
+ */
+void page_move_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ struct anon_vma *anon_vma = vma->anon_vma;
+
+ VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON(!anon_vma);
+ VM_BUG_ON(page->index != linear_page_index(vma, address));
+
+ anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+ page->mapping = (struct address_space *) anon_vma;
+}
+
+/**
* __page_set_anon_rmap - setup new anonymous rmap
* @page: the page to add the mapping to
* @vma: the vm area in which the mapping is added
@@ -652,9 +763,6 @@ static void __page_check_anon_rmap(struct page *page,
* are initially only visible via the pagetables, and the pte is locked
* over the call to page_add_new_anon_rmap.
*/
- struct anon_vma *anon_vma = vma->anon_vma;
- anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
- BUG_ON(page->mapping != (struct address_space *)anon_vma);
BUG_ON(page->index != linear_page_index(vma, address));
#endif
}
@@ -815,9 +923,9 @@ int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
if (PageAnon(page))
- dec_mm_counter(mm, anon_rss);
+ dec_mm_counter(mm, MM_ANONPAGES);
else
- dec_mm_counter(mm, file_rss);
+ dec_mm_counter(mm, MM_FILEPAGES);
set_pte_at(mm, address, pte,
swp_entry_to_pte(make_hwpoison_entry(page)));
} else if (PageAnon(page)) {
@@ -839,7 +947,8 @@ int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
list_add(&mm->mmlist, &init_mm.mmlist);
spin_unlock(&mmlist_lock);
}
- dec_mm_counter(mm, anon_rss);
+ dec_mm_counter(mm, MM_ANONPAGES);
+ inc_mm_counter(mm, MM_SWAPENTS);
} else if (PAGE_MIGRATION) {
/*
* Store the pfn of the page in a special migration
@@ -857,7 +966,7 @@ int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
entry = make_migration_entry(page, pte_write(pteval));
set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
} else
- dec_mm_counter(mm, file_rss);
+ dec_mm_counter(mm, MM_FILEPAGES);
page_remove_rmap(page);
page_cache_release(page);
@@ -996,7 +1105,7 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
page_remove_rmap(page);
page_cache_release(page);
- dec_mm_counter(mm, file_rss);
+ dec_mm_counter(mm, MM_FILEPAGES);
(*mapcount)--;
}
pte_unmap_unlock(pte - 1, ptl);
@@ -1024,14 +1133,15 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
{
struct anon_vma *anon_vma;
- struct vm_area_struct *vma;
+ struct anon_vma_chain *avc;
int ret = SWAP_AGAIN;
anon_vma = page_lock_anon_vma(page);
if (!anon_vma)
return ret;
- list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
+ list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
+ struct vm_area_struct *vma = avc->vma;
unsigned long address = vma_address(page, vma);
if (address == -EFAULT)
continue;
@@ -1222,7 +1332,7 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
struct vm_area_struct *, unsigned long, void *), void *arg)
{
struct anon_vma *anon_vma;
- struct vm_area_struct *vma;
+ struct anon_vma_chain *avc;
int ret = SWAP_AGAIN;
/*
@@ -1237,7 +1347,8 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
if (!anon_vma)
return ret;
spin_lock(&anon_vma->lock);
- list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
+ list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
+ struct vm_area_struct *vma = avc->vma;
unsigned long address = vma_address(page, vma);
if (address == -EFAULT)
continue;