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    Subject[PATCH v2 07/12] 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 | 19 ++++++++++---------
    mm/internal.h | 2 ++
    2 files changed, 12 insertions(+), 9 deletions(-)

    diff --git a/mm/hugetlb.c b/mm/hugetlb.c
    index e465582..4757e72 100644
    --- a/mm/hugetlb.c
    +++ b/mm/hugetlb.c
    @@ -1068,15 +1068,15 @@ 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
    @@ -1127,8 +1127,8 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
    if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
    goto err;

    - ac.gfp_mask = htlb_alloc_mask(h);
    - ac.nid = huge_node(vma, address, ac.gfp_mask, &mpol, &ac.nmask);
    + ac.__gfp_mask = htlb_alloc_mask(h);
    + ac.nid = huge_node(vma, address, ac.__gfp_mask, &mpol, &ac.nmask);

    page = dequeue_huge_page_nodemask(h, &ac);
    if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
    @@ -1951,7 +1951,7 @@ 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;
    @@ -1989,9 +1989,10 @@ 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->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) {
    @@ -2010,7 +2011,7 @@ 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 159cfd6..2dc0268 100644
    --- a/mm/internal.h
    +++ b/mm/internal.h
    @@ -619,6 +619,8 @@ struct alloc_control {
    nodemask_t *nmask;
    gfp_t gfp_mask;
    bool skip_cma;
    +
    + gfp_t __gfp_mask; /* Used internally in API implementation */
    };

    #endif /* __MM_INTERNAL_H */
    --
    2.7.4
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