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From: Charan Teja Reddy <charante@codeaurora.org>
To: akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, vinmenon@codeaurora.org,
	Charan Teja Reddy <charante@codeaurora.org>
Subject: [PATCH] mm: cma: improve pr_debug log in cma_release()
Date: Wed, 25 Nov 2020 21:02:21 +0530	[thread overview]
Message-ID: <1606318341-29521-1-git-send-email-charante@codeaurora.org> (raw)

It is required to print 'count' of pages, along with the pages, passed
to cma_release to debug the cases of mismatched count value passed
between cma_alloc() and cma_release() from a code path.

As an example, consider the below scenario:
1) CMA pool size is 4MB and
2) User doing the erroneous step of allocating 2 pages but freeing 1
page in a loop from this CMA pool.
The step 2 causes cma_alloc() to return NULL at one point of time
because of -ENOMEM condition.

And the current pr_debug logs is not giving the info about these types
of allocation patterns because of count value not being printed in
cma_release().

We are printing the count value in the trace logs, just extend the same
to pr_debug logs too.

Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
---
 mm/cma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/cma.c b/mm/cma.c
index 7f415d7..07c904b 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -512,7 +512,7 @@ bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
 	if (!cma || !pages)
 		return false;
 
-	pr_debug("%s(page %p)\n", __func__, (void *)pages);
+	pr_debug("%s(page %p, count %zu)\n", __func__, (void *)pages, count);
 
 	pfn = page_to_pfn(pages);
 
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation



             reply	other threads:[~2020-11-25 15:32 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-25 15:32 Charan Teja Reddy [this message]
2020-11-25 15:49 ` Souptick Joarder
2020-11-25 16:39 ` David Hildenbrand
2020-11-27 15:49 ` Vlastimil Babka

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