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[173/200] mm: cma: improve pr_debug log in cma_release()

Message ID 20201215031326.ufYu0ihF4%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/200] kthread: add kthread_work tracepoints | expand

Commit Message

Andrew Morton Dec. 15, 2020, 3:13 a.m. UTC 
From: Charan Teja Reddy <charante@codeaurora.org>
Subject: mm: cma: improve pr_debug log in cma_release()

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.

[akpm@linux-foundation.org: fix printk warning]
Link: https://lkml.kernel.org/r/1606318341-29521-1-git-send-email-charante@codeaurora.org
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
Reviewed-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/cma.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

--- a/mm/cma.c~mm-cma-improve-pr_debug-log-in-cma_release
+++ a/mm/cma.c
@@ -510,7 +510,7 @@  bool cma_release(struct cma *cma, const
 	if (!cma || !pages)
 		return false;
 
-	pr_debug("%s(page %p)\n", __func__, (void *)pages);
+	pr_debug("%s(page %p, count %u)\n", __func__, (void *)pages, count);
 
 	pfn = page_to_pfn(pages);