From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f53.google.com (mail-qg0-f53.google.com [209.85.192.53]) by kanga.kvack.org (Postfix) with ESMTP id 92D446B0035 for ; Thu, 28 Aug 2014 21:41:59 -0400 (EDT) Received: by mail-qg0-f53.google.com with SMTP id z107so1633596qgd.26 for ; Thu, 28 Aug 2014 18:41:59 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id 11si8425196qgl.90.2014.08.28.18.41.58 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Aug 2014 18:41:58 -0700 (PDT) From: Naoya Horiguchi Subject: [PATCH v3 4/6] mm/hugetlb: add migration entry check in hugetlb_change_protection Date: Thu, 28 Aug 2014 21:38:58 -0400 Message-Id: <1409276340-7054-5-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1409276340-7054-1-git-send-email-n-horiguchi@ah.jp.nec.com> References: <1409276340-7054-1-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 to do proper actions. ChangeLog v3: - handle migration entry correctly (instead of just skipping) Signed-off-by: Naoya Horiguchi Cc: # [2.6.36+] --- mm/hugetlb.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git mmotm-2014-08-25-16-52.orig/mm/hugetlb.c mmotm-2014-08-25-16-52/mm/hugetlb.c index 2aafe073cb06..1ed9df6def54 100644 --- mmotm-2014-08-25-16-52.orig/mm/hugetlb.c +++ mmotm-2014-08-25-16-52/mm/hugetlb.c @@ -3362,7 +3362,26 @@ 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_hwpoisoned(pte))) { + spin_unlock(ptl); + continue; + } + if (unlikely(is_hugetlb_entry_migration(pte))) { + swp_entry_t entry = pte_to_swp_entry(pte); + + if (is_write_migration_entry(entry)) { + pte_t newpte; + + make_migration_entry_read(&entry); + newpte = swp_entry_to_pte(entry); + set_pte_at(mm, address, ptep, newpte); + pages++; + } + 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