From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753516Ab3LCIzA (ORCPT ); Tue, 3 Dec 2013 03:55:00 -0500 Received: from cantor2.suse.de ([195.135.220.15]:49428 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752904Ab3LCIwJ (ORCPT ); Tue, 3 Dec 2013 03:52:09 -0500 From: Mel Gorman To: Alex Thorlton Cc: Rik van Riel , Linux-MM , LKML , Mel Gorman Subject: [PATCH 07/15] mm: numa: Do not clear PMD during PTE update scan Date: Tue, 3 Dec 2013 08:51:54 +0000 Message-Id: <1386060721-3794-8-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.8.4 In-Reply-To: <1386060721-3794-1-git-send-email-mgorman@suse.de> References: <1386060721-3794-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the PMD is flushed then a parallel fault in handle_mm_fault() will enter the pmd_none and do_huge_pmd_anonymous_page() path where it'll attempt to insert a huge zero page. This is wasteful so the patch avoids clearing the PMD when setting pmd_numa. Signed-off-by: Mel Gorman --- mm/huge_memory.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 203b5bc..d6c3bf4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1474,20 +1474,24 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, if (__pmd_trans_huge_lock(pmd, vma) == 1) { pmd_t entry; - entry = pmdp_get_and_clear(mm, addr, pmd); + if (!prot_numa) { + entry = pmdp_get_and_clear(mm, addr, pmd); entry = pmd_modify(entry, newprot); BUG_ON(pmd_write(entry)); + set_pmd_at(mm, addr, pmd, entry); } else { struct page *page = pmd_page(*pmd); + entry = *pmd; /* only check non-shared pages */ if (page_mapcount(page) == 1 && !pmd_numa(*pmd)) { entry = pmd_mknuma(entry); + set_pmd_at(mm, addr, pmd, entry); } } - set_pmd_at(mm, addr, pmd, entry); + spin_unlock(&vma->vm_mm->page_table_lock); ret = 1; } -- 1.8.4