Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932619AbbEEBwJ (ORCPT ); Mon, 4 May 2015 21:52:09 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51917 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932561AbbEEBv2 (ORCPT ); Mon, 4 May 2015 21:51:28 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Lee Schermerhorn" , "David Rientjes" , "James Hogan" , "Rik van Riel" , "Mel Gorman" , "Naoya Horiguchi" , "Steve Capper" , "Andrea Arcangeli" , "Hugh Dickins" , "Nishanth Aravamudan" , "Johannes Weiner" , "Michal Hocko" , "Luiz Capitulino" , "Linus Torvalds" Date: Tue, 05 May 2015 02:16:39 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 035/221] mm/hugetlb: add migration/hwpoisoned entry check in hugetlb_change_protection In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2659 Lines: 74 3.2.69-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Naoya Horiguchi commit a8bda28d87c38c6aa93de28ba5d30cc18e865a11 upstream. 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. Fixes: 290408d4a2 ("hugetlb: hugepage migration core") Signed-off-by: Naoya Horiguchi Cc: Hugh Dickins Cc: James Hogan Cc: David Rientjes Cc: Mel Gorman Cc: Johannes Weiner Cc: Michal Hocko Cc: Rik van Riel Cc: Andrea Arcangeli Cc: Luiz Capitulino Cc: Nishanth Aravamudan Cc: Lee Schermerhorn Cc: Steve Capper Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: - Adjust context - We don't have split page table locks, so don't unlock inside the loop - We don't count pages here] Signed-off-by: Ben Hutchings --- mm/hugetlb.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3037,7 +3037,22 @@ void hugetlb_change_protection(struct vm continue; if (huge_pmd_unshare(mm, &address, ptep)) continue; - if (!huge_pte_none(huge_ptep_get(ptep))) { + pte = huge_ptep_get(ptep); + if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) + 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); + } + continue; + } + if (!huge_pte_none(pte)) { pte = huge_ptep_get_and_clear(mm, address, ptep); pte = pte_mkhuge(pte_modify(pte, newprot)); set_huge_pte_at(mm, address, ptep, pte); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/