diff options
| -rw-r--r-- | mm/hugetlb.c | 62 |
1 files changed, 23 insertions, 39 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f260ffa26363..7dc80cbe8e89 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1540,62 +1540,46 @@ int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn) static struct page *__alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask, int nid, nodemask_t *nmask) { - struct page *page; - unsigned int r_nid; + struct page *page = NULL; if (hstate_is_gigantic(h)) return NULL; - /* - * Assume we will successfully allocate the surplus page to - * prevent racing processes from causing the surplus to exceed - * overcommit - * - * This however introduces a different race, where a process B - * tries to grow the static hugepage pool while alloc_pages() is - * called by process A. B will only examine the per-node - * counters in determining if surplus huge pages can be - * converted to normal huge pages in adjust_pool_surplus(). A - * won't be able to increment the per-node counter, until the - * lock is dropped by B, but B doesn't drop hugetlb_lock until - * no more huge pages can be converted from surplus to normal - * state (and doesn't try to convert again). Thus, we have a - * case where a surplus huge page exists, the pool is grown, and - * the surplus huge page still exists after, even though it - * should just have been converted to a normal huge page. This - * does not leak memory, though, as the hugepage will be freed - * once it is out of use. It also does not allow the counters to - * go out of whack in adjust_pool_surplus() as we don't modify - * the node values until we've gotten the hugepage and only the - * per-node value is checked there. - */ spin_lock(&hugetlb_lock); - if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { - spin_unlock(&hugetlb_lock); - return NULL; - } else { - h->nr_huge_pages++; - h->surplus_huge_pages++; - } + if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) + goto out_unlock; spin_unlock(&hugetlb_lock); page = __hugetlb_alloc_buddy_huge_page(h, gfp_mask, nid, nmask); + if (!page) + goto out_unlock; spin_lock(&hugetlb_lock); - if (page) { + /* + * We could have raced with the pool size change. + * Double check that and simply deallocate the new page + * if we would end up overcommiting the surpluses. Abuse + * temporary page to workaround the nasty free_huge_page + * codeflow + */ + if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { + SetPageHugeTemporary(page); + put_page(page); + page = NULL; + } else { + int r_nid; + + h->surplus_huge_pages++; + h->nr_huge_pages++; INIT_LIST_HEAD(&page->lru); r_nid = page_to_nid(page); set_compound_page_dtor(page, HUGETLB_PAGE_DTOR); set_hugetlb_cgroup(page, NULL); - /* - * We incremented the global counters already - */ h->nr_huge_pages_node[r_nid]++; h->surplus_huge_pages_node[r_nid]++; - } else { - h->nr_huge_pages--; - h->surplus_huge_pages--; } + +out_unlock: spin_unlock(&hugetlb_lock); return page; |