On Mon, 28 Dec 2020 21:29:01 +0800 Hailong liu <carver4lio@xxxxxxx> wrote:
> The trace point *trace_mm_page_alloc_zone_locked()* in __rmqueue() does not
> currently cover all branches. Add the missing tracepoint and check the page
> before do that.
>
> ...
>
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2871,7 +2871,7 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype,
> zone_page_state(zone, NR_FREE_PAGES) / 2) {
> page = __rmqueue_cma_fallback(zone, order);
> if (page)
> - return page;
> + goto out;
> }
> #endif
> retry:
> @@ -2884,8 +2884,9 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype,
> alloc_flags))
> goto retry;
> }
> -
> - trace_mm_page_alloc_zone_locked(page, order, migratetype);
> +out:
> + if (page)
> + trace_mm_page_alloc_zone_locked(page, order, migratetype);
> return page;
> }
Looks right to me, but it generates a warning. Using IS_ENABLED()
works around it.
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: mm-page_alloc-add-a-missing-mm_page_alloc_zone_locked-tracepoint-fix
use IS_ENABLED() to suppress warning
mm/page_alloc.c: In function ‘__rmqueue’:
mm/page_alloc.c:2889:1: warning: label ‘out’ defined but not used [-Wunused-label]
out:
^~~
Cc: Hailong liu <liu.hailong6@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-add-a-missing-mm_page_alloc_zone_locked-tracepoint-fix
+++ a/mm/page_alloc.c
@@ -2862,20 +2862,20 @@ __rmqueue(struct zone *zone, unsigned in
{
struct page *page;
-#ifdef CONFIG_CMA
- /*
- * Balance movable allocations between regular and CMA areas by
- * allocating from CMA when over half of the zone's free memory
- * is in the CMA area.
- */
- if (alloc_flags & ALLOC_CMA &&
- zone_page_state(zone, NR_FREE_CMA_PAGES) >
- zone_page_state(zone, NR_FREE_PAGES) / 2) {
- page = __rmqueue_cma_fallback(zone, order);
- if (page)
- goto out;
+ if (IS_ENABLED(CONFIG_CMA)) {
+ /*
+ * Balance movable allocations between regular and CMA areas by
+ * allocating from CMA when over half of the zone's free memory
+ * is in the CMA area.
+ */
+ if (alloc_flags & ALLOC_CMA &&
+ zone_page_state(zone, NR_FREE_CMA_PAGES) >
+ zone_page_state(zone, NR_FREE_PAGES) / 2) {
+ page = __rmqueue_cma_fallback(zone, order);
+ if (page)
+ goto out;
+ }
}
-#endif
retry:
page = __rmqueue_smallest(zone, order, migratetype);
if (unlikely(!page)) {
_
