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Subject[PATCH/RFC] Add helper for allocating and freeing discontiguous page array.
Date
Hi Andrew,

you suggested this helper and so I implemented it :-)
Diff is against Linus' current git. Compile tested with allyesconfig.
Checked with checkpatch.

Best Regards

Ingo Oeser

Signed-off-by: Ingo Oeser <ioe-lkml@rameria.de>
---
include/linux/gfp.h | 2 ++
mm/page_alloc.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 50 insertions(+), 0 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index e8003af..0e2453a 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -249,5 +249,7 @@ void page_alloc_init(void);
void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
void drain_all_pages(void);
void drain_local_pages(void *dummy);
+int alloc_page_array(struct page **pages, unsigned int count, gfp_t gfp_mask);
+void free_page_array(struct page **pages, unsigned int count);

#endif /* __LINUX_GFP_H */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 27b8681..459e4bb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1757,6 +1757,54 @@ void free_pages_exact(void *virt, size_t size)
}
EXPORT_SYMBOL(free_pages_exact);

+
+/**
+ * free_page_array - free a number of physically non-contiguous pages.
+ * @pages: the array for pages to free
+ * @count: the number of pages to free
+ */
+void free_page_array(struct page **pages, unsigned int count)
+{
+ unsigned int i;
+
+ for (i = 0; i < count; ++i) {
+ if (pages[i])
+ __free_page(pages[i]);
+ }
+}
+EXPORT_SYMBOL_GPL(free_page_array);
+
+/**
+ * alloc_page_array - allocate a number of physically non-contiguous pages.
+ * @pages: the array for pages to allocate into
+ * @count: the number of pages to allocate
+ * @gfp_mask: GFP flags for the allocation
+ *
+ * alloc_page_array can satisfy any number of pages.
+ *
+ * NOTE: The array of pages in pages is NOT physically or virtually contiguous!
+ * Use alloc_pages or similiar for physically contiguous pages or vmalloc
+ * and friends for virtually contiguous pages.
+ *
+ * Memory allocated by this function can be release via free_page_array.
+ *
+ * Returns 0 on success and %-ENOMEM on failure.
+ */
+int alloc_page_array(struct page **pages, unsigned int count, gfp_t gfp_mask)
+{
+ unsigned int i;
+
+ for (i = 0; i < count; ++i) {
+ pages[i] = alloc_page(gfp_mask);
+ if (!pages[i] && i > 0) {
+ free_page_array(pages, i);
+ return -ENOMEM;
+ }
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(alloc_page_array);
+
static unsigned int nr_free_zone_pages(int offset)
{
struct zoneref *z;
--
1.5.4.3


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