[PATCH v4] mm/hugetlb: avoid hardcoding while checking if cma is enabled

[PATCH v4] mm/hugetlb: avoid hardcoding while checking if cma is enabled

[Barry Song]

hugetlb_cma[0] can be NULL due to various reasons, for example, node0 has
no memory. so NULL hugetlb_cma[0] doesn't necessarily mean cma is not
enabled. gigantic pages might have been reserved on other nodes.
This patch fixes possible double reservation and CMA leak.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
---
 v4: address linux-next issue;
     use hugetlb_cma_size to check if cma is enabled

 mm/hugetlb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 57ece74e3aae..bc3304af40d0 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -46,6 +46,7 @@ unsigned int default_hstate_idx;
 struct hstate hstates[HUGE_MAX_HSTATE];
 
 static struct cma *hugetlb_cma[MAX_NUMNODES];
+static unsigned long hugetlb_cma_size __initdata;
 
 /*
  * Minimum page order among possible hugepage sizes, set to a proper value
@@ -2571,7 +2572,7 @@ static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
 
 	for (i = 0; i < h->max_huge_pages; ++i) {
 		if (hstate_is_gigantic(h)) {
-			if (IS_ENABLED(CONFIG_CMA) && hugetlb_cma[0]) {
+			if (hugetlb_cma_size) {
 				pr_warn_once("HugeTLB: hugetlb_cma is enabled, skip boot time allocation\n");
 				break;
 			}
@@ -5654,7 +5655,6 @@ void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
 }
 
 #ifdef CONFIG_CMA
-static unsigned long hugetlb_cma_size __initdata;
 static bool cma_reserve_called __initdata;
 
 static int __init cmdline_parse_hugetlb_cma(char *p)
-- 
2.27.0

Re: [PATCH v4] mm/hugetlb: avoid hardcoding while checking if cma is enabled

[Mike Kravetz]

On 7/9/20 5:57 PM, Barry Song wrote:
> hugetlb_cma[0] can be NULL due to various reasons, for example, node0 has
> no memory. so NULL hugetlb_cma[0] doesn't necessarily mean cma is not
> enabled. gigantic pages might have been reserved on other nodes.
> This patch fixes possible double reservation and CMA leak.
> 
> Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
> Cc: Mike Kravetz <mike.kravetz@oracle.com>
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Acked-by: Roman Gushchin <guro@fb.com>
> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>

Thank you!

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

-- 
Mike Kravetz