mm: Update is_vmalloc_addr to account for vmalloc savings

is_vmalloc_addr currently assumes that all vmalloc addresses
exist between VMALLOC_START and VMALLOC_END. This may not be
the case when interleaving vmalloc and lowmem. Update the
is_vmalloc_addr to properly check for this.

Correspondingly we need to ensure that VMALLOC_TOTAL accounts
for all the vmalloc regions when CONFIG_ENABLE_VMALLOC_SAVING
is enabled.

Change-Id: I5def3d6ae1a4de59ea36f095b8c73649a37b1f36
Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>
Signed-off-by: Zhenhua Huang <zhenhuah@codeaurora.org>

arch/arm/mm/mmu.c

@@ -1539,6 +1539,7 @@ static void __init map_lowmem(void)
 		vm->flags |= VM_ARM_MTYPE(type);
 		vm->caller = map_lowmem;
 		add_static_vm_early(svm++);
+		mark_vmalloc_reserved_area(vm->addr, vm->size);
 	}
 }
 

include/linux/mm.h

@@ -519,16 +519,16 @@ unsigned long vmalloc_to_pfn(const void *addr);
  * On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there
  * is no special casing required.
  */
-static inline bool is_vmalloc_addr(const void *x)
-{
-#ifdef CONFIG_MMU
-	unsigned long addr = (unsigned long)x;
 
-	return addr >= VMALLOC_START && addr < VMALLOC_END;
+#ifdef CONFIG_MMU
+extern int is_vmalloc_addr(const void *x);
 #else
-	return false;
-#endif
+static inline int is_vmalloc_addr(const void *x)
+{
+	return 0;
 }
+#endif
+
 #ifdef CONFIG_MMU
 extern int is_vmalloc_or_module_addr(const void *x);
 #else

include/linux/vmalloc.h

@@ -177,6 +177,12 @@ extern struct list_head vmap_area_list;
 extern __init void vm_area_add_early(struct vm_struct *vm);
 extern __init void vm_area_register_early(struct vm_struct *vm, size_t align);
 extern __init int vm_area_check_early(struct vm_struct *vm);
+#ifdef CONFIG_ENABLE_VMALLOC_SAVING
+extern void mark_vmalloc_reserved_area(void *addr, unsigned long size);
+#else
+static inline void mark_vmalloc_reserved_area(void *addr, unsigned long size)
+{ };
+#endif
 
 #ifdef CONFIG_SMP
 # ifdef CONFIG_MMU
@@ -202,7 +208,12 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
 #endif
 
 #ifdef CONFIG_MMU
+#ifdef CONFIG_ENABLE_VMALLOC_SAVING
+extern unsigned long total_vmalloc_size;
+#define VMALLOC_TOTAL total_vmalloc_size
+#else
 #define VMALLOC_TOTAL (VMALLOC_END - VMALLOC_START)
+#endif
 #else
 #define VMALLOC_TOTAL 0UL
 #endif

mm/vmalloc.c

@@ -347,6 +347,57 @@ unsigned long vmalloc_nr_pages(void)
 	return atomic_long_read(&nr_vmalloc_pages);
 }
 
+#ifdef CONFIG_ENABLE_VMALLOC_SAVING
+#define POSSIBLE_VMALLOC_START	PAGE_OFFSET
+
+#define VMALLOC_BITMAP_SIZE	((VMALLOC_END - PAGE_OFFSET) >> \
+					PAGE_SHIFT)
+#define VMALLOC_TO_BIT(addr)	((addr - PAGE_OFFSET) >> PAGE_SHIFT)
+#define BIT_TO_VMALLOC(i)	(PAGE_OFFSET + i * PAGE_SIZE)
+
+unsigned long total_vmalloc_size;
+static unsigned long vmalloc_reserved;
+
+static DECLARE_BITMAP(possible_areas, VMALLOC_BITMAP_SIZE);
+
+void mark_vmalloc_reserved_area(void *x, unsigned long size)
+{
+	unsigned long addr = (unsigned long)x;
+
+	bitmap_set(possible_areas, VMALLOC_TO_BIT(addr), size >> PAGE_SHIFT);
+	vmalloc_reserved += size;
+}
+
+int is_vmalloc_addr(const void *x)
+{
+	unsigned long addr = (unsigned long)x;
+
+	if (addr < POSSIBLE_VMALLOC_START || addr >= VMALLOC_END)
+		return 0;
+
+	if (test_bit(VMALLOC_TO_BIT(addr), possible_areas))
+		return 0;
+
+	return 1;
+}
+
+static void calc_total_vmalloc_size(void)
+{
+	total_vmalloc_size = VMALLOC_END - POSSIBLE_VMALLOC_START -
+		vmalloc_reserved;
+}
+#else
+int is_vmalloc_addr(const void *x)
+{
+	unsigned long addr = (unsigned long)x;
+
+	return addr >= VMALLOC_START && addr < VMALLOC_END;
+}
+
+static void calc_total_vmalloc_size(void) { }
+#endif
+EXPORT_SYMBOL(is_vmalloc_addr);
+
 static struct vmap_area *__find_vmap_area(unsigned long addr)
 {
 	struct rb_node *n = vmap_area_root.rb_node;
@@ -1318,7 +1369,7 @@ void __init vmalloc_init(void)
 	}
 
 	vmap_area_pcpu_hole = VMALLOC_END;
-
+	calc_total_vmalloc_size();
 	vmap_initialized = true;
 }
 
@@ -2790,6 +2841,9 @@ static int s_show(struct seq_file *m, void *p)
 	if (is_vmalloc_addr(v->pages))
 		seq_puts(m, " vpages");
 
+	if (v->flags & VM_LOWMEM)
+		seq_puts(m, " lowmem");
+
 	show_numa_info(m, v);
 	seq_putc(m, '\n');
 	return 0;