Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755247Ab2JRUNx (ORCPT ); Thu, 18 Oct 2012 16:13:53 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:47016 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755082Ab2JRUNw (ORCPT ); Thu, 18 Oct 2012 16:13:52 -0400 Date: Thu, 18 Oct 2012 13:13:48 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Bob Liu cc: akpm@linux-foundation.org, aarcange@redhat.com, xiaoguangrong@linux.vnet.ibm.com, hughd@google.com, linux-kernel@vger.kernel.org, kirill.shutemov@linux.intel.com Subject: Re: [PATCH 1/4] thp: clean up __collapse_huge_page_isolate In-Reply-To: <1350555140-11030-1-git-send-email-lliubbo@gmail.com> Message-ID: References: <1350555140-11030-1-git-send-email-lliubbo@gmail.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3014 Lines: 108 On Thu, 18 Oct 2012, Bob Liu wrote: > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index a863af2..462d6ea 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1700,64 +1700,49 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte) > } > } > > -static void release_all_pte_pages(pte_t *pte) > -{ > - release_pte_pages(pte, pte + HPAGE_PMD_NR); > -} > - > static int __collapse_huge_page_isolate(struct vm_area_struct *vma, > unsigned long address, > pte_t *pte) > { > struct page *page; > pte_t *_pte; > - int referenced = 0, isolated = 0, none = 0; > + int referenced = 0, isolated = 1, none = 0; > for (_pte = pte; _pte < pte+HPAGE_PMD_NR; > _pte++, address += PAGE_SIZE) { > pte_t pteval = *_pte; > if (pte_none(pteval)) { > if (++none <= khugepaged_max_ptes_none) > continue; > - else { > - release_pte_pages(pte, _pte); > + else > goto out; > - } > } > - if (!pte_present(pteval) || !pte_write(pteval)) { > - release_pte_pages(pte, _pte); > + if (!pte_present(pteval) || !pte_write(pteval)) > goto out; > - } > page = vm_normal_page(vma, address, pteval); > - if (unlikely(!page)) { > - release_pte_pages(pte, _pte); > + if (unlikely(!page)) > goto out; > - } > + > VM_BUG_ON(PageCompound(page)); > BUG_ON(!PageAnon(page)); > VM_BUG_ON(!PageSwapBacked(page)); > > /* cannot use mapcount: can't collapse if there's a gup pin */ > - if (page_count(page) != 1) { > - release_pte_pages(pte, _pte); > + if (page_count(page) != 1) > goto out; > - } > /* > * We can do it before isolate_lru_page because the > * page can't be freed from under us. NOTE: PG_lock > * is needed to serialize against split_huge_page > * when invoked from the VM. > */ > - if (!trylock_page(page)) { > - release_pte_pages(pte, _pte); > + if (!trylock_page(page)) > goto out; > - } > /* > * Isolate the page to avoid collapsing an hugepage > * currently in use by the VM. > */ > if (isolate_lru_page(page)) { > unlock_page(page); > - release_pte_pages(pte, _pte); > goto out; > } > /* 0 stands for page_is_file_cache(page) == false */ > @@ -1770,11 +1755,11 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, > mmu_notifier_test_young(vma->vm_mm, address)) > referenced = 1; > } > - if (unlikely(!referenced)) > - release_all_pte_pages(pte); > - else > - isolated = 1; > + if (unlikely(!referenced)) { > out: Labels inside of conditionals are never good if they can be avoided and in this case you can avoid it by doing if (likely(referenced)) return 1; out: ... > + release_pte_pages(pte, _pte); > + isolated = 0; > + } > return isolated; > } > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/