linux-kernel - [PATCH] mm/cma: Warn if the CMA area could not be activated

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Message-Id: <20170605023729.26303-1-khandual@linux.vnet.ibm.com>
Date:   Mon,  5 Jun 2017 08:07:29 +0530
From:   Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     akpm@...ux-foundation.org, aneesh.kumar@...ux.vnet.ibm.com,
        iamjoonsoo.kim@....com
Subject: [PATCH] mm/cma: Warn if the CMA area could not be activated

While activating the CMA area, we check to make sure that all the
PFNs in the range are inside the same zone. This is a requirement
for alloc_contig_range() to work. Any CMA area failing the check
is disabled for good. This happens silently right now making all
future cma_alloc() allocations failure inevitable. Here we add a
error message stating that the CMA area could not be activated
which makes its easier to explain any future cma_alloc() failures
on it. While at this, change the bail out goto label from 'err'
to 'not_in_zone' which makes more sense.

Signed-off-by: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
---
 mm/cma.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index 978b4a1..9e45491 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -127,7 +127,7 @@ static int __init cma_activate_area(struct cma *cma)
 			 * to be in the same zone.
 			 */
 			if (page_zone(pfn_to_page(pfn)) != zone)
-				goto err;
+				goto not_in_zone;
 		}
 		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
 	} while (--i);
@@ -141,7 +141,8 @@ static int __init cma_activate_area(struct cma *cma)

 	return 0;

-err:
+not_in_zone:
+	pr_err("CMA area %s could not be activated\n", cma->name);
 	kfree(cma->bitmap);
 	cma->count = 0;
 	return -EINVAL;
-- 
1.8.5.2