linux-kernel - [PATCH] mm/cma: Fix placement of trace_cma_alloc

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Date: Tue,  9 Jan 2024 17:22:33 -0800
From: Kalesh Singh <kaleshsingh@...gle.com>
To: minchan@...nel.org, akpm@...ux-foundation.org, lmark@...eaurora.org
Cc: surenb@...gle.com, android-mm@...gle.com, kernel-team@...roid.com, 
	Kalesh Singh <kaleshsingh@...gle.com>, Georgi Djakov <djakov@...nel.org>, 
	Liam Mark <quic_lmark@...cinc.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mm/cma: Fix placement of trace_cma_alloc_start/finish

The current placement of trace_cma_alloc_start/finish misses the
fail cases: !cma || !cma->count || !cma->bitmap.

trace_cma_alloc_finish is also not emitted for the failure case
where bitmap_count > bitmap_maxno.

Fix these missed cases by moving the start event before the failure
checks and moving the finish event to the out label.

Fixes: 7bc1aec5e287 ("mm: cma: add trace events for CMA alloc perf testing")
Cc: Minchan Kim <minchan@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Liam Mark <lmark@...eaurora.org>
Signed-off-by: Kalesh Singh <kaleshsingh@...gle.com>
---
 mm/cma.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index 2b2494fd6b59..8341f1217a85 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -436,6 +436,9 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	unsigned long i;
 	struct page *page = NULL;
 	int ret = -ENOMEM;
+	const char *name = cma ? cma->name : NULL;
+
+	trace_cma_alloc_start(name, count, align);
 
 	if (!cma || !cma->count || !cma->bitmap)
 		goto out;
@@ -446,8 +449,6 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	if (!count)
 		goto out;
 
-	trace_cma_alloc_start(cma->name, count, align);
-
 	mask = cma_bitmap_aligned_mask(cma, align);
 	offset = cma_bitmap_aligned_offset(cma, align);
 	bitmap_maxno = cma_bitmap_maxno(cma);
@@ -496,8 +497,6 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 		start = bitmap_no + mask + 1;
 	}
 
-	trace_cma_alloc_finish(cma->name, pfn, page, count, align, ret);
-
 	/*
 	 * CMA can allocate multiple page blocks, which results in different
 	 * blocks being marked with different tags. Reset the tags to ignore
@@ -516,6 +515,7 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 
 	pr_debug("%s(): returned %p\n", __func__, page);
 out:
+	trace_cma_alloc_finish(name, pfn, page, count, align, ret);
 	if (page) {
 		count_vm_event(CMA_ALLOC_SUCCESS);
 		cma_sysfs_account_success_pages(cma, count);

base-commit: 0dd3ee31125508cd67f7e7172247f05b7fd1753a
-- 
2.43.0.472.g3155946c3a-goog