From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753508AbcIBMpA (ORCPT ); Fri, 2 Sep 2016 08:45:00 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:32921 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752633AbcIBMo6 (ORCPT ); Fri, 2 Sep 2016 08:44:58 -0400 From: Ebru Akagunduz To: linux-mm@kvack.org Cc: riel@redhat.com, aarcange@redhat.com, akpm@linux-foundation.org, vbabka@suse.cz, mgorman@techsingularity.net, kirill.shutemov@linux.intel.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, Ebru Akagunduz Subject: [PATCH] mm, thp: fix leaking mapped pte in __collapse_huge_page_swapin() Date: Fri, 2 Sep 2016 15:44:36 +0300 Message-Id: <1472820276-7831-1-git-send-email-ebru.akagunduz@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, khugepaged does not let swapin, if there is no enough young pages in a THP. The problem is when a THP does not have enough young page, khugepaged leaks mapped ptes. This patch prohibits leaking mapped ptes. Signed-off-by: Ebru Akagunduz Suggested-by: Andrea Arcangeli --- mm/khugepaged.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 79c52d0..f401e9d 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -881,6 +881,11 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, .pmd = pmd, }; + /* we only decide to swapin, if there is enough young ptes */ + if (referenced < HPAGE_PMD_NR/2) { + trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); + return false; + } fe.pte = pte_offset_map(pmd, address); for (; fe.address < address + HPAGE_PMD_NR*PAGE_SIZE; fe.pte++, fe.address += PAGE_SIZE) { @@ -888,11 +893,6 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, if (!is_swap_pte(pteval)) continue; swapped_in++; - /* we only decide to swapin, if there is enough young ptes */ - if (referenced < HPAGE_PMD_NR/2) { - trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); - return false; - } ret = do_swap_page(&fe, pteval); /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ -- 1.9.1