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Subject[PATCH v2 14/20] mm, hugetlb: call vma_needs_reservation before entering alloc_huge_page()
Date
In order to validate that this failure is reasonable, we need to know
whether allocation request is for reserved or not on caller function.
So moving vma_needs_reservation() up to the caller of alloc_huge_page().
There is no functional change in this patch and following patch use
this information.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8dff972..bc666cf 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1110,13 +1110,11 @@ 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;
- long chg;
- bool use_reserve;
int ret, idx;
struct hugetlb_cgroup *h_cg;

@@ -1129,10 +1127,6 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
* need pages and subpool limit allocated allocated if no reserve
* mapping overlaps.
*/
- chg = vma_needs_reservation(h, vma, addr);
- if (chg < 0)
- return ERR_PTR(-ENOMEM);
- use_reserve = (!chg && !avoid_reserve);
if (!use_reserve)
if (hugepage_subpool_get_pages(spool, 1))
return ERR_PTR(-ENOSPC);
@@ -2504,6 +2498,8 @@ 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;
+ long chg;
+ bool use_reserve;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */

@@ -2535,7 +2531,17 @@ 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);
+ chg = vma_needs_reservation(h, vma, address);
+ if (chg == -ENOMEM) {
+ page_cache_release(old_page);
+
+ /* Caller expects lock to be held */
+ spin_lock(&mm->page_table_lock);
+ return VM_FAULT_OOM;
+ }
+ use_reserve = !chg && !outside_reserve;
+
+ new_page = alloc_huge_page(vma, address, use_reserve);

if (IS_ERR(new_page)) {
long err = PTR_ERR(new_page);
@@ -2664,6 +2670,8 @@ 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;
+ long chg;
+ bool use_reserve;

/*
* Currently, we are forced to kill the process in the event the
@@ -2689,7 +2697,15 @@ retry:
size = i_size_read(mapping->host) >> huge_page_shift(h);
if (idx >= size)
goto out;
- page = alloc_huge_page(vma, address, 0);
+
+ chg = vma_needs_reservation(h, vma, address);
+ if (chg == -ENOMEM) {
+ ret = VM_FAULT_OOM;
+ goto out;
+ }
+ use_reserve = !chg;
+
+ 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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