[PATCH] mm/cma: Fix placement of trace_cma_alloc_start/finish

From: Kalesh Singh
Date: Tue Jan 09 2024 - 20:22:55 EST


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@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Liam Mark <lmark@xxxxxxxxxxxxxx>
Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
---
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