[PATCH] mm/cma_sysfs: Skip inactive CMA areas in sysfs

[Kaitao Cheng <kaitao.cheng@linux.dev>]

From: Kaitao Cheng <chengkaitao@kylinos.cn>

cma_activate_area() can fail after a CMA area has already been added to
cma_areas[].  In that case the area is left in the global array, but it
does not reach the point where CMA_ACTIVATED is set.

cma_sysfs_init() currently walks all cma_area_count entries and creates
sysfs files for every area, including ones that failed activation.  These
areas are not usable CMA areas and should not be exposed to userspace as
valid CMA regions.

Skip CMA areas that did not reach CMA_ACTIVATED when creating the sysfs
objects.  Since inactive entries can now be skipped, make the error
unwind tolerate entries that never had cma_kobj initialized.

Fixes: 43ca106fa8ec ("mm: cma: support sysfs")
Reported-by: David Hildenbrand (Arm) <david@kernel.org>
Reported-by: Muchun Song <songmuchun@bytedance.com>
Closes: https://lore.kernel.org/linux-mm/55481a8b-dcfc-4bef-ba59-aa0b43dca88b@kernel.org/
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
---
 mm/cma_sysfs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/cma_sysfs.c b/mm/cma_sysfs.c
index f52b696bc46d..d5bf792c6245 100644
--- a/mm/cma_sysfs.c
+++ b/mm/cma_sysfs.c
@@ -117,13 +117,16 @@ static int __init cma_sysfs_init(void)
 		return -ENOMEM;
 
 	for (i = 0; i < cma_area_count; i++) {
+		cma = &cma_areas[i];
+		if (!test_bit(CMA_ACTIVATED, &cma->flags))
+			continue;
+
 		cma_kobj = kzalloc_obj(*cma_kobj);
 		if (!cma_kobj) {
 			err = -ENOMEM;
 			goto out;
 		}
 
-		cma = &cma_areas[i];
 		cma->cma_kobj = cma_kobj;
 		cma_kobj->cma = cma;
 		err = kobject_init_and_add(&cma_kobj->kobj, &cma_ktype,
@@ -138,7 +141,8 @@ static int __init cma_sysfs_init(void)
 out:
 	while (--i >= 0) {
 		cma = &cma_areas[i];
-		kobject_put(&cma->cma_kobj->kobj);
+		if (cma->cma_kobj)
+			kobject_put(&cma->cma_kobj->kobj);
 	}
 	kobject_put(cma_kobj_root);
 
-- 
2.50.1 (Apple Git-155)