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    SubjectRe: [PATCH] mm, hugetlb: move the error handle logic out of normal code path
    On Wed 14-05-14 15:10:59, Jianyu Zhan wrote:
    > alloc_huge_page() now mixes normal code path with error handle logic.
    > This patches move out the error handle logic, to make normal code
    > path more clean and redue code duplicate.

    I don't know. Part of the function returns and cleans up on its own and
    other part relies on clean up labels. This is not so much nicer than the
    previous state.

    > Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
    > ---
    > mm/hugetlb.c | 26 +++++++++++++-------------
    > 1 file changed, 13 insertions(+), 13 deletions(-)
    >
    > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
    > index 26b1464..e81c69e 100644
    > --- a/mm/hugetlb.c
    > +++ b/mm/hugetlb.c
    > @@ -1246,24 +1246,17 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
    > return ERR_PTR(-ENOSPC);
    >
    > ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
    > - if (ret) {
    > - if (chg || avoid_reserve)
    > - hugepage_subpool_put_pages(spool, 1);
    > - return ERR_PTR(-ENOSPC);
    > - }
    > + if (ret)
    > + goto out_subpool_put;
    > +
    > spin_lock(&hugetlb_lock);
    > page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg);
    > if (!page) {
    > spin_unlock(&hugetlb_lock);
    > page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
    > - if (!page) {
    > - hugetlb_cgroup_uncharge_cgroup(idx,
    > - pages_per_huge_page(h),
    > - h_cg);
    > - if (chg || avoid_reserve)
    > - hugepage_subpool_put_pages(spool, 1);
    > - return ERR_PTR(-ENOSPC);
    > - }
    > + if (!page)
    > + goto out_uncharge_cgroup;
    > +
    > spin_lock(&hugetlb_lock);
    > list_move(&page->lru, &h->hugepage_activelist);
    > /* Fall through */
    > @@ -1275,6 +1268,13 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
    >
    > vma_commit_reservation(h, vma, addr);
    > return page;
    > +
    > +out_uncharge_cgroup:
    > + hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
    > +out_subpool_put:
    > + if (chg || avoid_reserve)
    > + hugepage_subpool_put_pages(spool, 1);
    > + return ERR_PTR(-ENOSPC);
    > }
    >
    > /*
    > --
    > 2.0.0-rc3
    >

    --
    Michal Hocko
    SUSE Labs


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