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Subject[PATCH 06/11] mm/hugetlb: do not modify user provided gfp_mask
Date
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

It's not good practice to modify user input. Instead of using it to
build correct gfp_mask for APIs, this patch introduces another gfp_mask
field, __gfp_mask, for internal usage.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
mm/hugetlb.c | 15 ++++++++-------
mm/internal.h | 2 ++
2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 53edd02..5f43b7e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1069,15 +1069,15 @@ static struct page *dequeue_huge_page_nodemask(struct hstate *h,
struct zoneref *z;
int node = NUMA_NO_NODE;

- zonelist = node_zonelist(ac->nid, ac->gfp_mask);
+ zonelist = node_zonelist(ac->nid, ac->__gfp_mask);

retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
for_each_zone_zonelist_nodemask(zone, z, zonelist,
- gfp_zone(ac->gfp_mask), ac->nmask) {
+ gfp_zone(ac->__gfp_mask), ac->nmask) {
struct page *page;

- if (!cpuset_zone_allowed(zone, ac->gfp_mask))
+ if (!cpuset_zone_allowed(zone, ac->__gfp_mask))
continue;
/*
* no need to ask again on the same node. Pool is node rather than
@@ -1952,7 +1952,7 @@ static struct page *alloc_migrate_huge_page(struct hstate *h,
if (hstate_is_gigantic(h))
return NULL;

- page = alloc_fresh_huge_page(h, ac->gfp_mask,
+ page = alloc_fresh_huge_page(h, ac->__gfp_mask,
ac->nid, ac->nmask, NULL);
if (!page)
return NULL;
@@ -1990,9 +1990,10 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
struct page *alloc_huge_page_nodemask(struct hstate *h,
struct alloc_control *ac)
{
- ac->gfp_mask |= htlb_alloc_mask(h);
+ ac->__gfp_mask = htlb_alloc_mask(h);
+ ac->__gfp_mask |= ac->gfp_mask;
if (ac->thisnode && ac->nid != NUMA_NO_NODE)
- ac->gfp_mask |= __GFP_THISNODE;
+ ac->__gfp_mask |= __GFP_THISNODE;

spin_lock(&hugetlb_lock);
if (h->free_huge_pages - h->resv_huge_pages > 0) {
@@ -2011,7 +2012,7 @@ struct page *alloc_huge_page_nodemask(struct hstate *h,
* will not come from CMA area
*/
if (ac->skip_cma)
- ac->gfp_mask &= ~__GFP_MOVABLE;
+ ac->__gfp_mask &= ~__GFP_MOVABLE;

return alloc_migrate_huge_page(h, ac);
}
diff --git a/mm/internal.h b/mm/internal.h
index 6b6507e..3239d71 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -620,6 +620,8 @@ struct alloc_control {
gfp_t gfp_mask;
bool thisnode;
bool skip_cma;
+
+ gfp_t __gfp_mask; /* Used internally in API implementation */
};

#endif /* __MM_INTERNAL_H */
--
2.7.4
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