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Subject: [PATCH 2/2] perf/ring_buffer: Matching the memory allocate and free,
 in rb_alloc()
From:   Yunfeng Ye <yeyunfeng@huawei.com>
To:     <peterz@infradead.org>, <mingo@redhat.com>, <acme@kernel.org>,
        <mark.rutland@arm.com>, <alexander.shishkin@linux.intel.com>,
        <jolsa@redhat.co>, <namhyung@kernel.org>
CC:     <linux-kernel@vger.kernel.org>
References: <4d308608-54e2-05fa-5a1a-9cb7b4986bd1@huawei.com>
 <68211803-de9a-cae1-2627-6a5e5ae0853b@huawei.com>
Message-ID: <575c7e8c-90c7-4e3a-b41d-f894d8cdbd7f@huawei.com>
Date:   Mon, 14 Oct 2019 16:15:57 +0800
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Currently perf_mmap_alloc_page() is used to allocate memory in
rb_alloc(), but using free_page() to free memory in the failure path.

It's better to use perf_mmap_free_page() instead.

Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
---
 kernel/events/ring_buffer.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index abc145c..246c83a 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -754,6 +754,14 @@ static void *perf_mmap_alloc_page(int cpu)
 	return page_address(page);
 }

+static void perf_mmap_free_page(void *addr)
+{
+	struct page *page = virt_to_page(addr);
+
+	page->mapping = NULL;
+	__free_page(page);
+}
+
 struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
 {
 	struct ring_buffer *rb;
@@ -788,9 +796,9 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)

 fail_data_pages:
 	for (i--; i >= 0; i--)
-		free_page((unsigned long)rb->data_pages[i]);
+		perf_mmap_free_page(rb->data_pages[i]);

-	free_page((unsigned long)rb->user_page);
+	perf_mmap_free_page(rb->user_page);

 fail_user_page:
 	kfree(rb);
@@ -799,14 +807,6 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
 	return NULL;
 }

-static void perf_mmap_free_page(void *addr)
-{
-	struct page *page = virt_to_page(addr);
-
-	page->mapping = NULL;
-	__free_page(page);
-}
-
 void rb_free(struct ring_buffer *rb)
 {
 	int i;
-- 
2.7.4