Merge branch 'kbuild/rc-fixes' into kbuild/kconfig

We need to revert the temporary hack in 71ebc01, hence the merge.

1 files changed, 162 insertions, 24 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 38a336e2eea..87b9e8ad450 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -56,6 +56,7 @@
 #include <linux/memcontrol.h>
 #include <linux/mmu_notifier.h>
 #include <linux/migrate.h>
+#include <linux/hugetlb.h>
 
 #include <asm/tlbflush.h>
 
@@ -132,9 +133,14 @@ int anon_vma_prepare(struct vm_area_struct *vma)
 			if (unlikely(!anon_vma))
 				goto out_enomem_free_avc;
 			allocated = anon_vma;
+			/*
+			 * This VMA had no anon_vma yet.  This anon_vma is
+			 * the root of any anon_vma tree that might form.
+			 */
+			anon_vma->root = anon_vma;
 		}
 
-		spin_lock(&anon_vma->lock);
+		anon_vma_lock(anon_vma);
 		/* page_table_lock to protect against threads */
 		spin_lock(&mm->page_table_lock);
 		if (likely(!vma->anon_vma)) {
@@ -142,12 +148,12 @@ int anon_vma_prepare(struct vm_area_struct *vma)
 			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);
+			list_add_tail(&avc->same_anon_vma, &anon_vma->head);
 			allocated = NULL;
 			avc = NULL;
 		}
 		spin_unlock(&mm->page_table_lock);
-		spin_unlock(&anon_vma->lock);
+		anon_vma_unlock(anon_vma);
 
 		if (unlikely(allocated))
 			anon_vma_free(allocated);
@@ -170,9 +176,9 @@ static void anon_vma_chain_link(struct vm_area_struct *vma,
 	avc->anon_vma = anon_vma;
 	list_add(&avc->same_vma, &vma->anon_vma_chain);
 
-	spin_lock(&anon_vma->lock);
+	anon_vma_lock(anon_vma);
 	list_add_tail(&avc->same_anon_vma, &anon_vma->head);
-	spin_unlock(&anon_vma->lock);
+	anon_vma_unlock(anon_vma);
 }
 
 /*
@@ -224,9 +230,21 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
 	avc = anon_vma_chain_alloc();
 	if (!avc)
 		goto out_error_free_anon_vma;
-	anon_vma_chain_link(vma, avc, anon_vma);
+
+	/*
+	 * The root anon_vma's spinlock is the lock actually used when we
+	 * lock any of the anon_vmas in this anon_vma tree.
+	 */
+	anon_vma->root = pvma->anon_vma->root;
+	/*
+	 * With KSM refcounts, an anon_vma can stay around longer than the
+	 * process it belongs to.  The root anon_vma needs to be pinned
+	 * until this anon_vma is freed, because the lock lives in the root.
+	 */
+	get_anon_vma(anon_vma->root);
 	/* Mark this anon_vma as the one where our new (COWed) pages go. */
 	vma->anon_vma = anon_vma;
+	anon_vma_chain_link(vma, avc, anon_vma);
 
 	return 0;
 
@@ -246,22 +264,29 @@ static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain)
 	if (!anon_vma)
 		return;
 
-	spin_lock(&anon_vma->lock);
+	anon_vma_lock(anon_vma);
 	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) && !anonvma_external_refcount(anon_vma);
-	spin_unlock(&anon_vma->lock);
+	anon_vma_unlock(anon_vma);
 
-	if (empty)
+	if (empty) {
+		/* We no longer need the root anon_vma */
+		if (anon_vma->root != anon_vma)
+			drop_anon_vma(anon_vma->root);
 		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. */
+	/*
+	 * Unlink each anon_vma chained to the VMA.  This list is ordered
+	 * from newest to oldest, ensuring the root anon_vma gets freed last.
+	 */
 	list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
 		anon_vma_unlink(avc);
 		list_del(&avc->same_vma);
@@ -302,7 +327,7 @@ struct anon_vma *page_lock_anon_vma(struct page *page)
 		goto out;
 
 	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
-	spin_lock(&anon_vma->lock);
+	anon_vma_lock(anon_vma);
 	return anon_vma;
 out:
 	rcu_read_unlock();
@@ -311,7 +336,7 @@ out:
 
 void page_unlock_anon_vma(struct anon_vma *anon_vma)
 {
-	spin_unlock(&anon_vma->lock);
+	anon_vma_unlock(anon_vma);
 	rcu_read_unlock();
 }
 
@@ -326,6 +351,8 @@ vma_address(struct page *page, struct vm_area_struct *vma)
 	pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
 	unsigned long address;
 
+	if (unlikely(is_vm_hugetlb_page(vma)))
+		pgoff = page->index << huge_page_order(page_hstate(page));
 	address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
 	if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
 		/* page should be within @vma mapping range */
@@ -340,9 +367,10 @@ vma_address(struct page *page, struct vm_area_struct *vma)
  */
 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 {
-	if (PageAnon(page))
-		;
-	else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
+	if (PageAnon(page)) {
+		if (vma->anon_vma->root != page_anon_vma(page)->root)
+			return -EFAULT;
+	} else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
 		if (!vma->vm_file ||
 		    vma->vm_file->f_mapping != page->mapping)
 			return -EFAULT;
@@ -369,6 +397,12 @@ pte_t *page_check_address(struct page *page, struct mm_struct *mm,
 	pte_t *pte;
 	spinlock_t *ptl;
 
+	if (unlikely(PageHuge(page))) {
+		pte = huge_pte_offset(mm, address);
+		ptl = &mm->page_table_lock;
+		goto check;
+	}
+
 	pgd = pgd_offset(mm, address);
 	if (!pgd_present(*pgd))
 		return NULL;
@@ -389,6 +423,7 @@ pte_t *page_check_address(struct page *page, struct mm_struct *mm,
 	}
 
 	ptl = pte_lockptr(mm, pmd);
+check:
 	spin_lock(ptl);
 	if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
 		*ptlp = ptl;
@@ -743,14 +778,20 @@ static void __page_set_anon_rmap(struct page *page,
 	 * If the page isn't exclusively mapped into this vma,
 	 * we must use the _oldest_ possible anon_vma for the
 	 * page mapping!
-	 *
-	 * So take the last AVC chain entry in the vma, which is
-	 * the deepest ancestor, and use the anon_vma from that.
 	 */
 	if (!exclusive) {
-		struct anon_vma_chain *avc;
-		avc = list_entry(vma->anon_vma_chain.prev, struct anon_vma_chain, same_vma);
-		anon_vma = avc->anon_vma;
+		if (PageAnon(page))
+			return;
+		anon_vma = anon_vma->root;
+	} else {
+		/*
+		 * In this case, swapped-out-but-not-discarded swap-cache
+		 * is remapped. So, no need to update page->mapping here.
+		 * We convice anon_vma poitned by page->mapping is not obsolete
+		 * because vma->anon_vma is necessary to be a family of it.
+		 */
+		if (PageAnon(page))
+			return;
 	}
 
 	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
@@ -780,6 +821,7 @@ 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.
 	 */
+	BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
 	BUG_ON(page->index != linear_page_index(vma, address));
 #endif
 }
@@ -798,6 +840,17 @@ static void __page_check_anon_rmap(struct page *page,
 void page_add_anon_rmap(struct page *page,
 	struct vm_area_struct *vma, unsigned long address)
 {
+	do_page_add_anon_rmap(page, vma, address, 0);
+}
+
+/*
+ * Special version of the above for do_swap_page, which often runs
+ * into pages that are exclusively owned by the current process.
+ * Everybody else should continue to use page_add_anon_rmap above.
+ */
+void do_page_add_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
 	int first = atomic_inc_and_test(&page->_mapcount);
 	if (first)
 		__inc_zone_page_state(page, NR_ANON_PAGES);
@@ -807,7 +860,7 @@ void page_add_anon_rmap(struct page *page,
 	VM_BUG_ON(!PageLocked(page));
 	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
 	if (first)
-		__page_set_anon_rmap(page, vma, address, 0);
+		__page_set_anon_rmap(page, vma, address, exclusive);
 	else
 		__page_check_anon_rmap(page, vma, address);
 }
@@ -873,6 +926,12 @@ void page_remove_rmap(struct page *page)
 		page_clear_dirty(page);
 		set_page_dirty(page);
 	}
+	/*
+	 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
+	 * and not charged by memcg for now.
+	 */
+	if (unlikely(PageHuge(page)))
+		return;
 	if (PageAnon(page)) {
 		mem_cgroup_uncharge_page(page);
 		__dec_zone_page_state(page, NR_ANON_PAGES);
@@ -1368,6 +1427,42 @@ int try_to_munlock(struct page *page)
 		return try_to_unmap_file(page, TTU_MUNLOCK);
 }
 
+#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
+/*
+ * Drop an anon_vma refcount, freeing the anon_vma and anon_vma->root
+ * if necessary.  Be careful to do all the tests under the lock.  Once
+ * we know we are the last user, nobody else can get a reference and we
+ * can do the freeing without the lock.
+ */
+void drop_anon_vma(struct anon_vma *anon_vma)
+{
+	BUG_ON(atomic_read(&anon_vma->external_refcount) <= 0);
+	if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) {
+		struct anon_vma *root = anon_vma->root;
+		int empty = list_empty(&anon_vma->head);
+		int last_root_user = 0;
+		int root_empty = 0;
+
+		/*
+		 * The refcount on a non-root anon_vma got dropped.  Drop
+		 * the refcount on the root and check if we need to free it.
+		 */
+		if (empty && anon_vma != root) {
+			BUG_ON(atomic_read(&root->external_refcount) <= 0);
+			last_root_user = atomic_dec_and_test(&root->external_refcount);
+			root_empty = list_empty(&root->head);
+		}
+		anon_vma_unlock(anon_vma);
+
+		if (empty) {
+			anon_vma_free(anon_vma);
+			if (root_empty && last_root_user)
+				anon_vma_free(root);
+		}
+	}
+}
+#endif
+
 #ifdef CONFIG_MIGRATION
 /*
  * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
@@ -1389,7 +1484,7 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
 	anon_vma = page_anon_vma(page);
 	if (!anon_vma)
 		return ret;
-	spin_lock(&anon_vma->lock);
+	anon_vma_lock(anon_vma);
 	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);
@@ -1399,7 +1494,7 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
 		if (ret != SWAP_AGAIN)
 			break;
 	}
-	spin_unlock(&anon_vma->lock);
+	anon_vma_unlock(anon_vma);
 	return ret;
 }
 
@@ -1445,3 +1540,46 @@ int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
 		return rmap_walk_file(page, rmap_one, arg);
 }
 #endif /* CONFIG_MIGRATION */
+
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * The following three functions are for anonymous (private mapped) hugepages.
+ * Unlike common anonymous pages, anonymous hugepages have no accounting code
+ * and no lru code, because we handle hugepages differently from common pages.
+ */
+static void __hugepage_set_anon_rmap(struct page *page,
+	struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
+	struct anon_vma *anon_vma = vma->anon_vma;
+	BUG_ON(!anon_vma);
+	if (!exclusive) {
+		struct anon_vma_chain *avc;
+		avc = list_entry(vma->anon_vma_chain.prev,
+				 struct anon_vma_chain, same_vma);
+		anon_vma = avc->anon_vma;
+	}
+	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+	page->mapping = (struct address_space *) anon_vma;
+	page->index = linear_page_index(vma, address);
+}
+
+void hugepage_add_anon_rmap(struct page *page,
+			    struct vm_area_struct *vma, unsigned long address)
+{
+	struct anon_vma *anon_vma = vma->anon_vma;
+	int first;
+	BUG_ON(!anon_vma);
+	BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+	first = atomic_inc_and_test(&page->_mapcount);
+	if (first)
+		__hugepage_set_anon_rmap(page, vma, address, 0);
+}
+
+void hugepage_add_new_anon_rmap(struct page *page,
+			struct vm_area_struct *vma, unsigned long address)
+{
+	BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+	atomic_set(&page->_mapcount, 0);
+	__hugepage_set_anon_rmap(page, vma, address, 1);
+}
+#endif /* CONFIG_HUGETLB_PAGE */