mm: vmstat: add cma statistics

Since CMA is used more widely, it's worth to have CMA allocation
statistics into vmstat.  With it, we could know how agressively system
uses cma allocation and how often it fails.

Link: https://lkml.kernel.org/r/20210302183346.3707237-1-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: John Dias <joaodias@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/vm_event_item.h

@@ -70,6 +70,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 #endif
 #ifdef CONFIG_HUGETLB_PAGE
 		HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
+#endif
+#ifdef CONFIG_CMA
+		CMA_ALLOC_SUCCESS,
+		CMA_ALLOC_FAIL,
 #endif
 		UNEVICTABLE_PGCULLED,	/* culled to noreclaim list */
 		UNEVICTABLE_PGSCANNED,	/* scanned for reclaimability */

mm/cma.c

@@ -435,21 +435,21 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
 	int ret = -ENOMEM;
 
 	if (!cma || !cma->count || !cma->bitmap)
-		return NULL;
+		goto out;
 
 	pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
 		 count, align);
 
 	if (!count)
-		return NULL;
+		goto out;
 
 	mask = cma_bitmap_aligned_mask(cma, align);
 	offset = cma_bitmap_aligned_offset(cma, align);
 	bitmap_maxno = cma_bitmap_maxno(cma);
 	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
 
 	if (bitmap_count > bitmap_maxno)
-		return NULL;
+		goto out;
 
 	for (;;) {
 		spin_lock_irq(&cma->lock);
@@ -506,6 +506,12 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
 	}
 
 	pr_debug("%s(): returned %p\n", __func__, page);
+out:
+	if (page)
+		count_vm_event(CMA_ALLOC_SUCCESS);
+	else
+		count_vm_event(CMA_ALLOC_FAIL);
+
 	return page;
 }
 

mm/vmstat.c

@@ -1312,6 +1312,10 @@ const char * const vmstat_text[] = {
 #ifdef CONFIG_HUGETLB_PAGE
 	"htlb_buddy_alloc_success",
 	"htlb_buddy_alloc_fail",
+#endif
+#ifdef CONFIG_CMA
+	"cma_alloc_success",
+	"cma_alloc_fail",
 #endif
 	"unevictable_pgs_culled",
 	"unevictable_pgs_scanned",