Merge branch 'akpm' (patches from Andrew)

Merge vm fixes from Andrew Morton:
 "5 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm/sparse: fix kernel crash with pfn_section_valid check
  mm: fork: fix kernel_stack memcg stats for various stack implementations
  hugetlb_cgroup: fix illegal access to memory
  drivers/base/memory.c: indicate all memory blocks as removable
  mm/swapfile.c: move inode_lock out of claim_swapfile

drivers/base/memory.c

@@ -97,30 +97,13 @@ static ssize_t phys_index_show(struct device *dev,
 }
 
 /*
- * Show whether the memory block is likely to be offlineable (or is already
- * offline). Once offline, the memory block could be removed. The return
- * value does, however, not indicate that there is a way to remove the
- * memory block.
+ * Legacy interface that we cannot remove. Always indicate "removable"
+ * with CONFIG_MEMORY_HOTREMOVE - bad heuristic.
  */
 static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
 			      char *buf)
 {
-	struct memory_block *mem = to_memory_block(dev);
-	unsigned long pfn;
-	int ret = 1, i;
-
-	if (mem->state != MEM_ONLINE)
-		goto out;
-
-	for (i = 0; i < sections_per_block; i++) {
-		if (!present_section_nr(mem->start_section_nr + i))
-			continue;
-		pfn = section_nr_to_pfn(mem->start_section_nr + i);
-		ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
-	}
-
-out:
-	return sprintf(buf, "%d\n", ret);
+	return sprintf(buf, "%d\n", (int)IS_ENABLED(CONFIG_MEMORY_HOTREMOVE));
 }
 
 /*

include/linux/memcontrol.h

@@ -695,6 +695,7 @@ static inline unsigned long lruvec_page_state_local(struct lruvec *lruvec,
 void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
 			int val);
 void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val);
+void mod_memcg_obj_state(void *p, int idx, int val);
 
 static inline void mod_lruvec_state(struct lruvec *lruvec,
 				    enum node_stat_item idx, int val)
@@ -1123,6 +1124,10 @@ static inline void __mod_lruvec_slab_state(void *p, enum node_stat_item idx,
 	__mod_node_page_state(page_pgdat(page), idx, val);
 }
 
+static inline void mod_memcg_obj_state(void *p, int idx, int val)
+{
+}
+
 static inline
 unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 					    gfp_t gfp_mask,
@@ -1427,6 +1432,8 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
 	return memcg ? memcg->kmemcg_id : -1;
 }
 
+struct mem_cgroup *mem_cgroup_from_obj(void *p);
+
 #else
 
 static inline int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
@@ -1468,6 +1475,11 @@ static inline void memcg_put_cache_ids(void)
 {
 }
 
+static inline struct mem_cgroup *mem_cgroup_from_obj(void *p)
+{
+       return NULL;
+}
+
 #endif /* CONFIG_MEMCG_KMEM */
 
 #endif /* _LINUX_MEMCONTROL_H */

kernel/fork.c

@@ -397,8 +397,8 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
 		mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
 				    THREAD_SIZE / 1024 * account);
 
-		mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
-				     account * (THREAD_SIZE / 1024));
+		mod_memcg_obj_state(stack, MEMCG_KERNEL_STACK_KB,
+				    account * (THREAD_SIZE / 1024));
 	}
 }
 

mm/hugetlb_cgroup.c

@@ -240,8 +240,7 @@ again:
 	if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages,
 				     &counter)) {
 		ret = -ENOMEM;
-		hugetlb_event(hugetlb_cgroup_from_counter(counter, idx), idx,
-			      HUGETLB_MAX);
+		hugetlb_event(h_cg, idx, HUGETLB_MAX);
 	}
 	css_put(&h_cg->css);
 done:

mm/memcontrol.c

@@ -777,6 +777,17 @@ void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val)
 	rcu_read_unlock();
 }
 
+void mod_memcg_obj_state(void *p, int idx, int val)
+{
+	struct mem_cgroup *memcg;
+
+	rcu_read_lock();
+	memcg = mem_cgroup_from_obj(p);
+	if (memcg)
+		mod_memcg_state(memcg, idx, val);
+	rcu_read_unlock();
+}
+
 /**
  * __count_memcg_events - account VM events in a cgroup
  * @memcg: the memory cgroup
@@ -2661,6 +2672,33 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 }
 
 #ifdef CONFIG_MEMCG_KMEM
+/*
+ * Returns a pointer to the memory cgroup to which the kernel object is charged.
+ *
+ * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
+ * cgroup_mutex, etc.
+ */
+struct mem_cgroup *mem_cgroup_from_obj(void *p)
+{
+	struct page *page;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	page = virt_to_head_page(p);
+
+	/*
+	 * Slab pages don't have page->mem_cgroup set because corresponding
+	 * kmem caches can be reparented during the lifetime. That's why
+	 * memcg_from_slab_page() should be used instead.
+	 */
+	if (PageSlab(page))
+		return memcg_from_slab_page(page);
+
+	/* All other pages use page->mem_cgroup */
+	return page->mem_cgroup;
+}
+
 static int memcg_alloc_cache_id(void)
 {
 	int id, size;

mm/sparse.c

@@ -781,6 +781,12 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
 			ms->usage = NULL;
 		}
 		memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
+		/*
+		 * Mark the section invalid so that valid_section()
+		 * return false. This prevents code from dereferencing
+		 * ms->usage array.
+		 */
+		ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
 	}
 
 	if (section_is_early && memmap)

mm/swapfile.c

@@ -2899,10 +2899,6 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
 		p->bdev = inode->i_sb->s_bdev;
 	}
 
-	inode_lock(inode);
-	if (IS_SWAPFILE(inode))
-		return -EBUSY;
-
 	return 0;
 }
 
@@ -3157,36 +3153,41 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	mapping = swap_file->f_mapping;
 	inode = mapping->host;
 
-	/* will take i_rwsem; */
 	error = claim_swapfile(p, inode);
 	if (unlikely(error))
 		goto bad_swap;
 
+	inode_lock(inode);
+	if (IS_SWAPFILE(inode)) {
+		error = -EBUSY;
+		goto bad_swap_unlock_inode;
+	}
+
 	/*
 	 * Read the swap header.
 	 */
 	if (!mapping->a_ops->readpage) {
 		error = -EINVAL;
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 	}
 	page = read_mapping_page(mapping, 0, swap_file);
 	if (IS_ERR(page)) {
 		error = PTR_ERR(page);
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 	}
 	swap_header = kmap(page);
 
 	maxpages = read_swap_header(p, swap_header, inode);
 	if (unlikely(!maxpages)) {
 		error = -EINVAL;
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 	}
 
 	/* OK, set up the swap map and apply the bad block list */
 	swap_map = vzalloc(maxpages);
 	if (!swap_map) {
 		error = -ENOMEM;
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 	}
 
 	if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
@@ -3211,7 +3212,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 					GFP_KERNEL);
 		if (!cluster_info) {
 			error = -ENOMEM;
-			goto bad_swap;
+			goto bad_swap_unlock_inode;
 		}
 
 		for (ci = 0; ci < nr_cluster; ci++)
@@ -3220,7 +3221,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		p->percpu_cluster = alloc_percpu(struct percpu_cluster);
 		if (!p->percpu_cluster) {
 			error = -ENOMEM;
-			goto bad_swap;
+			goto bad_swap_unlock_inode;
 		}
 		for_each_possible_cpu(cpu) {
 			struct percpu_cluster *cluster;
@@ -3234,13 +3235,13 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 
 	error = swap_cgroup_swapon(p->type, maxpages);
 	if (error)
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 
 	nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
 		cluster_info, maxpages, &span);
 	if (unlikely(nr_extents < 0)) {
 		error = nr_extents;
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 	}
 	/* frontswap enabled? set up bit-per-page map for frontswap */
 	if (IS_ENABLED(CONFIG_FRONTSWAP))
@@ -3280,7 +3281,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 
 	error = init_swap_address_space(p->type, maxpages);
 	if (error)
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 
 	/*
 	 * Flush any pending IO and dirty mappings before we start using this
@@ -3290,7 +3291,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	error = inode_drain_writes(inode);
 	if (error) {
 		inode->i_flags &= ~S_SWAPFILE;
-		goto bad_swap;
+		goto bad_swap_unlock_inode;
 	}
 
 	mutex_lock(&swapon_mutex);
@@ -3315,6 +3316,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 
 	error = 0;
 	goto out;
+bad_swap_unlock_inode:
+	inode_unlock(inode);
 bad_swap:
 	free_percpu(p->percpu_cluster);
 	p->percpu_cluster = NULL;
@@ -3322,6 +3325,7 @@ bad_swap:
 		set_blocksize(p->bdev, p->old_block_size);
 		blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
 	}
+	inode = NULL;
 	destroy_swap_extents(p);
 	swap_cgroup_swapoff(p->type);
 	spin_lock(&swap_lock);
@@ -3333,13 +3337,8 @@ bad_swap:
 	kvfree(frontswap_map);
 	if (inced_nr_rotate_swap)
 		atomic_dec(&nr_rotate_swap);
-	if (swap_file) {
-		if (inode) {
-			inode_unlock(inode);
-			inode = NULL;
-		}
+	if (swap_file)
 		filp_close(swap_file, NULL);
-	}
 out:
 	if (page && !IS_ERR(page)) {
 		kunmap(page);