Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> writes: > If we fail with a reserved page, just calling put_page() is not sufficient, > because put_page() invoke free_huge_page() at last step and it doesn't > know whether a page comes from a reserved pool or not. So it doesn't do > anything related to reserved count. This makes reserve count lower > than how we need, because reserve count already decrease in > dequeue_huge_page_vma(). This patch fix this situation. You may want to document you are using PagePrivate for tracking reservation and why it is ok to that. > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 6c8eec2..3f834f1 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -572,6 +572,7 @@ retry_cpuset: > if (!vma_has_reserves(vma, chg)) > break; > > + SetPagePrivate(page); > h->resv_huge_pages--; > break; > } > @@ -626,15 +627,20 @@ static void free_huge_page(struct page *page) > int nid = page_to_nid(page); > struct hugepage_subpool *spool = > (struct hugepage_subpool *)page_private(page); > + bool restore_reserve; > > set_page_private(page, 0); > page->mapping = NULL; > BUG_ON(page_count(page)); > BUG_ON(page_mapcount(page)); > + restore_reserve = PagePrivate(page); > > spin_lock(&hugetlb_lock); > hugetlb_cgroup_uncharge_page(hstate_index(h), > pages_per_huge_page(h), page); > + if (restore_reserve) > + h->resv_huge_pages++; > + > if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) { > /* remove the page from active list */ > list_del(&page->lru); > @@ -2616,6 +2622,8 @@ retry_avoidcopy: > spin_lock(&mm->page_table_lock); > ptep = huge_pte_offset(mm, address & huge_page_mask(h)); > if (likely(pte_same(huge_ptep_get(ptep), pte))) { > + ClearPagePrivate(new_page); > + > /* Break COW */ > huge_ptep_clear_flush(vma, address, ptep); > set_huge_pte_at(mm, address, ptep, > @@ -2727,6 +2735,7 @@ retry: > goto retry; > goto out; > } > + ClearPagePrivate(page); > > spin_lock(&inode->i_lock); > inode->i_blocks += blocks_per_huge_page(h); > @@ -2773,8 +2782,10 @@ retry: > if (!huge_pte_none(huge_ptep_get(ptep))) > goto backout; > > - if (anon_rmap) > + if (anon_rmap) { > + ClearPagePrivate(page); > hugepage_add_new_anon_rmap(page, vma, address); > + } > else > page_dup_rmap(page); > new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) > -- > 1.7.9.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>