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-rw-r--r--mm/ksm.c172
1 files changed, 157 insertions, 15 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index af5f571185d5..2f58ceebfe8f 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -196,6 +196,13 @@ static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait);
static DEFINE_MUTEX(ksm_thread_mutex);
static DEFINE_SPINLOCK(ksm_mmlist_lock);
+/*
+ * Temporary hack for page_referenced_ksm() and try_to_unmap_ksm(),
+ * later we rework things a little to get the right vma to them.
+ */
+static DEFINE_SPINLOCK(ksm_fallback_vma_lock);
+static struct vm_area_struct ksm_fallback_vma;
+
#define KSM_KMEM_CACHE(__struct, __flags) kmem_cache_create("ksm_"#__struct,\
sizeof(struct __struct), __alignof__(struct __struct),\
(__flags), NULL)
@@ -445,14 +452,20 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
{
if (rmap_item->address & STABLE_FLAG) {
struct stable_node *stable_node;
+ struct page *page;
stable_node = rmap_item->head;
+ page = stable_node->page;
+ lock_page(page);
+
hlist_del(&rmap_item->hlist);
- if (stable_node->hlist.first)
+ if (stable_node->hlist.first) {
+ unlock_page(page);
ksm_pages_sharing--;
- else {
- set_page_stable_node(stable_node->page, NULL);
- put_page(stable_node->page);
+ } else {
+ set_page_stable_node(page, NULL);
+ unlock_page(page);
+ put_page(page);
rb_erase(&stable_node->node, &root_stable_tree);
free_stable_node(stable_node);
@@ -710,7 +723,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
}
get_page(kpage);
- page_add_ksm_rmap(kpage);
+ page_add_anon_rmap(kpage, vma, addr);
flush_cache_page(vma, addr, pte_pfn(*ptep));
ptep_clear_flush(vma, addr, ptep);
@@ -763,8 +776,16 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
pages_identical(page, kpage))
err = replace_page(vma, page, kpage, orig_pte);
- if ((vma->vm_flags & VM_LOCKED) && !err)
+ if ((vma->vm_flags & VM_LOCKED) && !err) {
munlock_vma_page(page);
+ if (!PageMlocked(kpage)) {
+ unlock_page(page);
+ lru_add_drain();
+ lock_page(kpage);
+ mlock_vma_page(kpage);
+ page = kpage; /* for final unlock */
+ }
+ }
unlock_page(page);
out:
@@ -841,7 +862,11 @@ static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item,
copy_user_highpage(kpage, page, rmap_item->address, vma);
+ SetPageDirty(kpage);
+ __SetPageUptodate(kpage);
+ SetPageSwapBacked(kpage);
set_page_stable_node(kpage, NULL); /* mark it PageKsm */
+ lru_cache_add_lru(kpage, LRU_ACTIVE_ANON);
err = try_to_merge_one_page(vma, page, kpage);
up:
@@ -1071,7 +1096,9 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
* The page was successfully merged:
* add its rmap_item to the stable tree.
*/
+ lock_page(kpage);
stable_tree_append(rmap_item, stable_node);
+ unlock_page(kpage);
}
put_page(kpage);
return;
@@ -1112,11 +1139,13 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
if (kpage) {
remove_rmap_item_from_tree(tree_rmap_item);
+ lock_page(kpage);
stable_node = stable_tree_insert(kpage);
if (stable_node) {
stable_tree_append(tree_rmap_item, stable_node);
stable_tree_append(rmap_item, stable_node);
}
+ unlock_page(kpage);
put_page(kpage);
/*
@@ -1285,14 +1314,6 @@ static void ksm_do_scan(unsigned int scan_npages)
return;
if (!PageKsm(page) || !in_stable_tree(rmap_item))
cmp_and_merge_page(page, rmap_item);
- else if (page_mapcount(page) == 1) {
- /*
- * Replace now-unshared ksm page by ordinary page.
- */
- break_cow(rmap_item);
- remove_rmap_item_from_tree(rmap_item);
- rmap_item->oldchecksum = calc_checksum(page);
- }
put_page(page);
}
}
@@ -1337,7 +1358,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE |
VM_PFNMAP | VM_IO | VM_DONTEXPAND |
VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE |
- VM_MIXEDMAP | VM_SAO))
+ VM_NONLINEAR | VM_MIXEDMAP | VM_SAO))
return 0; /* just ignore the advice */
if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
@@ -1435,6 +1456,127 @@ void __ksm_exit(struct mm_struct *mm)
}
}
+struct page *ksm_does_need_to_copy(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ struct page *new_page;
+
+ unlock_page(page); /* any racers will COW it, not modify it */
+
+ new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+ if (new_page) {
+ copy_user_highpage(new_page, page, address, vma);
+
+ SetPageDirty(new_page);
+ __SetPageUptodate(new_page);
+ SetPageSwapBacked(new_page);
+ __set_page_locked(new_page);
+
+ if (page_evictable(new_page, vma))
+ lru_cache_add_lru(new_page, LRU_ACTIVE_ANON);
+ else
+ add_page_to_unevictable_list(new_page);
+ }
+
+ page_cache_release(page);
+ return new_page;
+}
+
+int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg,
+ unsigned long *vm_flags)
+{
+ struct stable_node *stable_node;
+ struct rmap_item *rmap_item;
+ struct hlist_node *hlist;
+ unsigned int mapcount = page_mapcount(page);
+ int referenced = 0;
+ struct vm_area_struct *vma;
+
+ VM_BUG_ON(!PageKsm(page));
+ VM_BUG_ON(!PageLocked(page));
+
+ stable_node = page_stable_node(page);
+ if (!stable_node)
+ return 0;
+
+ /*
+ * Temporary hack: really we need anon_vma in rmap_item, to
+ * provide the correct vma, and to find recently forked instances.
+ * Use zalloc to avoid weirdness if any other fields are involved.
+ */
+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_ATOMIC);
+ if (!vma) {
+ spin_lock(&ksm_fallback_vma_lock);
+ vma = &ksm_fallback_vma;
+ }
+
+ hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) {
+ if (memcg && !mm_match_cgroup(rmap_item->mm, memcg))
+ continue;
+
+ vma->vm_mm = rmap_item->mm;
+ vma->vm_start = rmap_item->address;
+ vma->vm_end = vma->vm_start + PAGE_SIZE;
+
+ referenced += page_referenced_one(page, vma,
+ rmap_item->address, &mapcount, vm_flags);
+ if (!mapcount)
+ goto out;
+ }
+out:
+ if (vma == &ksm_fallback_vma)
+ spin_unlock(&ksm_fallback_vma_lock);
+ else
+ kmem_cache_free(vm_area_cachep, vma);
+ return referenced;
+}
+
+int try_to_unmap_ksm(struct page *page, enum ttu_flags flags)
+{
+ struct stable_node *stable_node;
+ struct hlist_node *hlist;
+ struct rmap_item *rmap_item;
+ int ret = SWAP_AGAIN;
+ struct vm_area_struct *vma;
+
+ VM_BUG_ON(!PageKsm(page));
+ VM_BUG_ON(!PageLocked(page));
+
+ stable_node = page_stable_node(page);
+ if (!stable_node)
+ return SWAP_FAIL;
+
+ /*
+ * Temporary hack: really we need anon_vma in rmap_item, to
+ * provide the correct vma, and to find recently forked instances.
+ * Use zalloc to avoid weirdness if any other fields are involved.
+ */
+ if (TTU_ACTION(flags) != TTU_UNMAP)
+ return SWAP_FAIL;
+
+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_ATOMIC);
+ if (!vma) {
+ spin_lock(&ksm_fallback_vma_lock);
+ vma = &ksm_fallback_vma;
+ }
+
+ hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) {
+ vma->vm_mm = rmap_item->mm;
+ vma->vm_start = rmap_item->address;
+ vma->vm_end = vma->vm_start + PAGE_SIZE;
+
+ ret = try_to_unmap_one(page, vma, rmap_item->address, flags);
+ if (ret != SWAP_AGAIN || !page_mapped(page))
+ goto out;
+ }
+out:
+ if (vma == &ksm_fallback_vma)
+ spin_unlock(&ksm_fallback_vma_lock);
+ else
+ kmem_cache_free(vm_area_cachep, vma);
+ return ret;
+}
+
#ifdef CONFIG_SYSFS
/*
* This all compiles without CONFIG_SYSFS, but is a waste of space.