From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751635AbbIQN2a (ORCPT ); Thu, 17 Sep 2015 09:28:30 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:34687 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751059AbbIQN22 (ORCPT ); Thu, 17 Sep 2015 09:28:28 -0400 Date: Thu, 17 Sep 2015 16:28:25 +0300 From: "Kirill A. Shutemov" To: Ebru Akagunduz Cc: linux-mm@kvack.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, riel@redhat.com, iamjoonsoo.kim@lge.com, xiexiuqi@huawei.com, gorcunov@openvz.org, linux-kernel@vger.kernel.org, mgorman@suse.de, rientjes@google.com, vbabka@suse.cz, aneesh.kumar@linux.vnet.ibm.com, hughd@google.com, hannes@cmpxchg.org, mhocko@suse.cz, boaz@plexistor.com, raindel@mellanox.com Subject: Re: [RFC v5 3/3] mm: make swapin readahead to improve thp collapse rate Message-ID: <20150917132825.GA30954@node.dhcp.inet.fi> References: <1442259105-4420-1-git-send-email-ebru.akagunduz@gmail.com> <1442259105-4420-4-git-send-email-ebru.akagunduz@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1442259105-4420-4-git-send-email-ebru.akagunduz@gmail.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 14, 2015 at 10:31:45PM +0300, Ebru Akagunduz wrote: > @@ -2655,6 +2696,8 @@ static void collapse_huge_page(struct mm_struct *mm, > > anon_vma_lock_write(vma->anon_vma); > > + __collapse_huge_page_swapin(mm, vma, address, pmd, pte); > + Do I miss something, or 'pte' is not initialized at this point? And the value is not really used in __collapse_huge_page_swapin(). > pte = pte_offset_map(pmd, address); > pte_ptl = pte_lockptr(mm, pmd); >>From 76783e1dfb22cde04cf46903336810df8a632617 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Thu, 17 Sep 2015 16:23:30 +0300 Subject: [PATCH] khugepaged: __collapse_huge_page_swapin(): drop unused 'pte' parameter 'pte' dereference is eliminated by compiler, since nobody uses the pteval until it's overwritten inside the loop. Value of 'pte' itself is overwritten by pte_offset_map() before first real use. Signed-off-by: Kirill A. Shutemov --- mm/huge_memory.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4b057abd8615..5ad5c443cc94 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2628,11 +2628,10 @@ static bool hugepage_vma_check(struct vm_area_struct *vma) static void __collapse_huge_page_swapin(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long address, pmd_t *pmd, - pte_t *pte) + unsigned long address, pmd_t *pmd) { unsigned long _address; - pte_t pteval = *pte; + pte_t *pte, pteval; int swapped_in = 0, ret = 0; pte = pte_offset_map(pmd, address); @@ -2730,7 +2729,7 @@ static void collapse_huge_page(struct mm_struct *mm, anon_vma_lock_write(vma->anon_vma); - __collapse_huge_page_swapin(mm, vma, address, pmd, pte); + __collapse_huge_page_swapin(mm, vma, address, pmd); pte = pte_offset_map(pmd, address); pte_ptl = pte_lockptr(mm, pmd); -- Kirill A. Shutemov