From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f46.google.com (mail-qg0-f46.google.com [209.85.192.46]) by kanga.kvack.org (Postfix) with ESMTP id 7AB5D6B00A2 for ; Mon, 15 Sep 2014 18:41:06 -0400 (EDT) Received: by mail-qg0-f46.google.com with SMTP id q107so4777076qgd.33 for ; Mon, 15 Sep 2014 15:41:01 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id w106si4543187qgd.98.2014.09.15.15.41.01 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Sep 2014 15:41:01 -0700 (PDT) From: Naoya Horiguchi Subject: [PATCH v3 4/5] mm/hugetlb: add migration/hwpoisoned entry check in hugetlb_change_protection Date: Mon, 15 Sep 2014 18:39:58 -0400 Message-Id: <1410820799-27278-5-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1410820799-27278-1-git-send-email-n-horiguchi@ah.jp.nec.com> References: <1410820799-27278-1-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 , stable@vger.kernel.org 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. HWPoison entries also can cause the same problem. This patch adds is_hugetlb_entry_(migration|hwpoisoned) check in this function to do proper actions. Signed-off-by: Naoya Horiguchi Cc: # [2.6.36+] --- ChangeLog v4: - s/set_pte_at/set_huge_pte_at/ ChangeLog v3: - handle migration entry correctly (instead of just skipping) --- mm/hugetlb.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git mmotm-2014-09-09-14-42.orig/mm/hugetlb.c mmotm-2014-09-09-14-42/mm/hugetlb.c index 52f001943169..461ee1e10067 100644 --- mmotm-2014-09-09-14-42.orig/mm/hugetlb.c +++ mmotm-2014-09-09-14-42/mm/hugetlb.c @@ -3372,7 +3372,26 @@ 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_huge_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