[patch 129/262] mm/cma: add cma_pages_valid to determine if pages are in CMA

Andrew Morton
2021-11-05T20:41:27Z

From: Mike Kravetz <mike.kravetz@oracle.com>
Subject: mm/cma: add cma_pages_valid to determine if pages are in CMA

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.

In order to keep the same amount of DEBUG information, a pr_debug() call
was added to cma_pages_valid(). In the case where the page passed to
cma_release is not in cma region, the debug message will be printed from
cma_pages_valid as opposed to cma_release.

Link: https://lkml.kernel.org/r/20211007181918.136982-3-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Nghia Le <nghialm78@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

include/linux/cma.h | 1 +
mm/cma.c | 24 ++++++++++++++++++++----
2 files changed, 21 insertions(+), 4 deletions(-)

--- a/include/linux/cma.h~mm-cma-add-cma_pages_valid-to-determine-if-pages-are-in-cma
+++ a/include/linux/cma.h
@@ -46,6 +46,7 @@ extern int cma_init_reserved_mem(phys_ad
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);
--- a/mm/cma.c~mm-cma-add-cma_pages_valid-to-determine-if-pages-are-in-cma
+++ a/mm/cma.c
@@ -524,6 +524,25 @@ out:
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) {
+ pr_debug("%s(page %p, count %lu)\n", __func__,
+ (void *)pages, count);
+ return false;
+ }
+
+ return true;
+}
+
/**
* cma_release() - release allocated pages
* @cma: Contiguous memory region for which the allocation is performed.
@@ -539,16 +558,13 @@ bool cma_release(struct cma *cma, const
{
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);
_