[PATCH v3 2/5] mm/cma: add cma_pages_valid to determine if pages are in CMA

[Mike Kravetz <mike.kravetz@oracle.com>]

Add new interface cma_pages_valid() which indicates if the specified
pages are part of a CMA region.  This interface will be used in a
subsequent patch by hugetlb code.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 include/linux/cma.h |  1 +
 mm/cma.c            | 21 +++++++++++++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index 53fd8c3cdbd0..bd801023504b 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -46,6 +46,7 @@ extern int cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
 					struct cma **res_cma);
 extern struct page *cma_alloc(struct cma *cma, unsigned long count, unsigned int align,
 			      bool no_warn);
+extern bool cma_pages_valid(struct cma *cma, const struct page *pages, unsigned long count);
 extern bool cma_release(struct cma *cma, const struct page *pages, unsigned long count);
 
 extern int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data);
diff --git a/mm/cma.c b/mm/cma.c
index 995e15480937..960994b88c7f 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -524,6 +524,22 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	return page;
 }
 
+bool cma_pages_valid(struct cma *cma, const struct page *pages,
+		     unsigned long count)
+{
+	unsigned long pfn;
+
+	if (!cma || !pages)
+		return false;
+
+	pfn = page_to_pfn(pages);
+
+	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
+		return false;
+
+	return true;
+}
+
 /**
  * cma_release() - release allocated pages
  * @cma:   Contiguous memory region for which the allocation is performed.
@@ -539,16 +555,13 @@ bool cma_release(struct cma *cma, const struct page *pages,
 {
 	unsigned long pfn;
 
-	if (!cma || !pages)
+	if (!cma_pages_valid(cma, pages, count))
 		return false;
 
 	pr_debug("%s(page %p, count %lu)\n", __func__, (void *)pages, count);
 
 	pfn = page_to_pfn(pages);
 
-	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
-		return false;
-
 	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
 
 	free_contig_range(pfn, count);
-- 
2.31.1