[PATCH v1] driver/base/memory.c: Validate memory block size early

[David Hildenbrand]

Let's validate the memory block size early, when initializing the
memory device infrastructure. Fail hard in case the value is not
suitable.

As nobody checks the return value of memory_dev_init(), turn it into a
void function and fail with a panic in all scenarios instead. Otherwise,
we'll crash later during boot when core/drivers expect that the memory
device infrastructure (including memory_block_size_bytes()) works as
expected.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 drivers/base/memory.c  | 31 +++++++++----------------------
 include/linux/memory.h |  6 +++---
 2 files changed, 12 insertions(+), 25 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 790b3bcd63a6..6bea4f3f8040 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -100,21 +100,6 @@ unsigned long __weak memory_block_size_bytes(void)
 }
 EXPORT_SYMBOL_GPL(memory_block_size_bytes);
 
-static unsigned long get_memory_block_size(void)
-{
-	unsigned long block_sz;
-
-	block_sz = memory_block_size_bytes();
-
-	/* Validate blk_sz is a power of 2 and not less than section size */
-	if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE)) {
-		WARN_ON(1);
-		block_sz = MIN_MEMORY_BLOCK_SIZE;
-	}
-
-	return block_sz;
-}
-
 /*
  * Show the first physical section index (number) of this memory block.
  */
@@ -461,7 +446,7 @@ static DEVICE_ATTR_RO(removable);
 static ssize_t block_size_bytes_show(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%lx\n", get_memory_block_size());
+	return sprintf(buf, "%lx\n", memory_block_size_bytes());
 }
 
 static DEVICE_ATTR_RO(block_size_bytes);
@@ -811,19 +796,22 @@ static const struct attribute_group *memory_root_attr_groups[] = {
 /*
  * Initialize the sysfs support for memory devices...
  */
-int __init memory_dev_init(void)
+void __init memory_dev_init(void)
 {
 	int ret;
 	int err;
 	unsigned long block_sz, nr;
 
+	/* Validate the configured memory block size */
+	block_sz = memory_block_size_bytes();
+	if (!is_power_of_2(block_sz) || block_sz < MIN_MEMORY_BLOCK_SIZE)
+		panic("Memory block size not suitable: 0x%lx\n", block_sz);
+	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
+
 	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
 	if (ret)
 		goto out;
 
-	block_sz = get_memory_block_size();
-	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
-
 	/*
 	 * Create entries for memory sections that were found
 	 * during boot and have been initialized
@@ -839,8 +827,7 @@ int __init memory_dev_init(void)
 
 out:
 	if (ret)
-		printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
-	return ret;
+		panic("%s() failed: %d\n", __func__, ret);
 }
 
 /**
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 704215d7258a..0ebb105eb261 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -79,9 +79,9 @@ struct mem_section;
 #define IPC_CALLBACK_PRI        10
 
 #ifndef CONFIG_MEMORY_HOTPLUG_SPARSE
-static inline int memory_dev_init(void)
+static inline void memory_dev_init(void)
 {
-	return 0;
+	return;
 }
 static inline int register_memory_notifier(struct notifier_block *nb)
 {
@@ -112,7 +112,7 @@ extern int register_memory_isolate_notifier(struct notifier_block *nb);
 extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
 int create_memory_block_devices(unsigned long start, unsigned long size);
 void remove_memory_block_devices(unsigned long start, unsigned long size);
-extern int memory_dev_init(void);
+extern void memory_dev_init(void);
 extern int memory_notify(unsigned long val, void *v);
 extern int memory_isolate_notify(unsigned long val, void *v);
 extern struct memory_block *find_memory_block(struct mem_section *);
-- 
2.21.0