On 09/23/2019 04:47 PM, Matthew Wilcox wrote:

On Mon, Sep 23, 2019 at 11:13:45AM +0530, Anshuman Khandual wrote:

quoted

+#ifdef CONFIG_MEMORY_HOTPLUG
+static void free_hotplug_page_range(struct page *page, size_t size)
+{
+	WARN_ON(!page || PageReserved(page));

WARN_ON(!page) isn't terribly useful.  You're going to crash on the very
next line when you call page_address() anyway.  If this line were

	if (WARN_ON(!page || PageReserved(page)))
		return;

it would make sense, or if it were just

	WARN_ON(PageReserved(page))

it would also make sense.

I guess WARN_ON(PageReserved(page)) should be good enough to make sure
that page being freed here was originally allocated at runtime for a
previous memory hot add operation and did not some how come from the
memblock reserved area. That was the original objective for this check.
Will change it.

quoted

+	free_pages((unsigned long)page_address(page), get_order(size));
+}

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