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SubjectRe: [PATCH 10/18] mm, hugetlb: call vma_has_reserve() before entering alloc_huge_page()
On Mon, Jul 29, 2013 at 02:27:54PM -0400, Naoya Horiguchi wrote:
> On Mon, Jul 29, 2013 at 02:32:01PM +0900, Joonsoo Kim wrote:
> > To implement a graceful failure handling, we need to know whether
> > allocation request is for reserved pool or not, on higher level.
> > In this patch, we just move up vma_has_reseve() to caller function
> > in order to know it. There is no functional change.
> >
> > Following patches implement a grace failure handling and remove
> > a hugetlb_instantiation_mutex.
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index a66226e..5f31ca5 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1123,12 +1123,12 @@ static void vma_commit_reservation(struct hstate *h,
> > }
> >
> > static struct page *alloc_huge_page(struct vm_area_struct *vma,
> > - unsigned long addr, int avoid_reserve)
> > + unsigned long addr, int use_reserve)
> > {
> > struct hugepage_subpool *spool = subpool_vma(vma);
> > struct hstate *h = hstate_vma(vma);
> > struct page *page;
> > - int ret, idx, use_reserve;
> > + int ret, idx;
> > struct hugetlb_cgroup *h_cg;
> >
> > idx = hstate_index(h);
> > @@ -1140,11 +1140,6 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> > * need pages and subpool limit allocated allocated if no reserve
> > * mapping overlaps.
> > */
> > - use_reserve = vma_has_reserves(h, vma, addr);
> > - if (use_reserve < 0)
> > - return ERR_PTR(-ENOMEM);
> > -
> > - use_reserve = use_reserve && !avoid_reserve;
> > if (!use_reserve && (hugepage_subpool_get_pages(spool, 1) < 0))
> > return ERR_PTR(-ENOSPC);
> >
> > @@ -2520,7 +2515,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
> > {
> > struct hstate *h = hstate_vma(vma);
> > struct page *old_page, *new_page;
> > - int outside_reserve = 0;
> > + int use_reserve, outside_reserve = 0;
> > unsigned long mmun_start; /* For mmu_notifiers */
> > unsigned long mmun_end; /* For mmu_notifiers */
> >
> > @@ -2553,7 +2548,18 @@ retry_avoidcopy:
> >
> > /* Drop page_table_lock as buddy allocator may be called */
> > spin_unlock(&mm->page_table_lock);
> > - new_page = alloc_huge_page(vma, address, outside_reserve);
> > +
> > + use_reserve = vma_has_reserves(h, vma, address);
> > + if (use_reserve == -ENOMEM) {
> > + page_cache_release(old_page);
> > +
> > + /* Caller expects lock to be held */
> > + spin_lock(&mm->page_table_lock);
> > + return VM_FAULT_OOM;
> > + }
> > + use_reserve = use_reserve && !outside_reserve;
>
> When outside_reserve is true, we don't have to call vma_has_reserves
> because then use_reserve is always false. So something like:
>
> use_reserve = 0;
> if (!outside_reserve) {
> use_reserve = vma_has_reserves(...);
> ...
> }
>
> looks better to me.
> Or if you expect vma_has_reserves to change resv_map implicitly,
> could you add a comment about it.

Yes, you are right.
I will change it.

Thanks.

>
> Thanks,
> Naoya Horiguchi
>
> > +
> > + new_page = alloc_huge_page(vma, address, use_reserve);
> >
> > if (IS_ERR(new_page)) {
> > long err = PTR_ERR(new_page);
> > @@ -2679,6 +2685,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
> > struct page *page;
> > struct address_space *mapping;
> > pte_t new_pte;
> > + int use_reserve = 0;
> >
> > /*
> > * Currently, we are forced to kill the process in the event the
> > @@ -2704,7 +2711,14 @@ retry:
> > size = i_size_read(mapping->host) >> huge_page_shift(h);
> > if (idx >= size)
> > goto out;
> > - page = alloc_huge_page(vma, address, 0);
> > +
> > + use_reserve = vma_has_reserves(h, vma, address);
> > + if (use_reserve == -ENOMEM) {
> > + ret = VM_FAULT_OOM;
> > + goto out;
> > + }
> > +
> > + page = alloc_huge_page(vma, address, use_reserve);
> > if (IS_ERR(page)) {
> > ret = PTR_ERR(page);
> > if (ret == -ENOMEM)
> > --
> > 1.7.9.5
> >
>
> --
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