From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qa0-f52.google.com (mail-qa0-f52.google.com [209.85.216.52]) by kanga.kvack.org (Postfix) with ESMTP id 8CBC26B0036 for ; Fri, 1 Aug 2014 13:40:56 -0400 (EDT) Received: by mail-qa0-f52.google.com with SMTP id j15so4217053qaq.39 for ; Fri, 01 Aug 2014 10:40:56 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id b7si16699932qab.106.2014.08.01.10.40.55 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Aug 2014 10:40:56 -0700 (PDT) From: Naoya Horiguchi Subject: [PATCH v2 3/3] mm/hugetlb: add migration entry check in hugetlb_change_protection Date: Fri, 1 Aug 2014 13:37:43 -0400 Message-Id: <1406914663-8631-3-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1406914663-8631-1-git-send-email-n-horiguchi@ah.jp.nec.com> References: <1406914663-8631-1-git-send-email-n-horiguchi@ah.jp.nec.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Hugh Dickins Cc: David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Naoya Horiguchi There is a race condition between hugepage migration and change_protection(), where hugetlb_change_protection() doesn't care about migration entries and wrongly overwrites them. That causes unexpected results like kernel crash. This patch adds is_hugetlb_entry_(migration|hwpoisoned) check in this function and skip all such entries. Signed-off-by: Naoya Horiguchi Cc: # [3.12+] --- mm/hugetlb.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git mmotm-2014-07-22-15-58.orig/mm/hugetlb.c mmotm-2014-07-22-15-58/mm/hugetlb.c index 863f45f63cd5..1da7ca2e2a02 100644 --- mmotm-2014-07-22-15-58.orig/mm/hugetlb.c +++ mmotm-2014-07-22-15-58/mm/hugetlb.c @@ -3355,7 +3355,13 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, spin_unlock(ptl); continue; } - if (!huge_pte_none(huge_ptep_get(ptep))) { + pte = huge_ptep_get(ptep); + if (unlikely(is_hugetlb_entry_migration(pte) || + is_hugetlb_entry_hwpoisoned(pte))) { + spin_unlock(ptl); + continue; + } + if (!huge_pte_none(pte)) { pte = huge_ptep_get_and_clear(mm, address, ptep); pte = pte_mkhuge(huge_pte_modify(pte, newprot)); pte = arch_make_huge_pte(pte, vma, NULL, 0); -- 1.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org