From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10903C64E7A for ; Tue, 17 Nov 2020 14:05:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0AEC20829 for ; Tue, 17 Nov 2020 14:05:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="qFQGG2Hq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731091AbgKQOEZ (ORCPT ); Tue, 17 Nov 2020 09:04:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:40000 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729488AbgKQNKg (ORCPT ); Tue, 17 Nov 2020 08:10:36 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 12B56221EB; Tue, 17 Nov 2020 13:10:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605618635; bh=sDle4BanFvLiTyXPkW94/wH0luaWEP4b4rv4Z2/qip0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qFQGG2HqC3TsGv4QW6DICIAZtMdUcUIe9M/qQFmYzW5cDKKxEI7zcYEe1ZG88qR0j r2z+zreJ3sgVsx1kll6ofbg/kzBNG49Li6nnSlQPp4Nnk5SNp6NJOpZ1pf0hpDxXg2 I8pZjzkKnDdKtglJCBr0VFN1Xv6RvmNsP4dShY1A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shijie Luo , Miaohe Lin , Andrew Morton , Oscar Salvador , Michal Hocko , Feilong Lin , Linus Torvalds , Sasha Levin Subject: [PATCH 4.9 04/78] mm: mempolicy: fix potential pte_unmap_unlock pte error Date: Tue, 17 Nov 2020 14:04:30 +0100 Message-Id: <20201117122109.334051504@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201117122109.116890262@linuxfoundation.org> References: <20201117122109.116890262@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Shijie Luo [ Upstream commit 3f08842098e842c51e3b97d0dcdebf810b32558e ] When flags in queue_pages_pte_range don't have MPOL_MF_MOVE or MPOL_MF_MOVE_ALL bits, code breaks and passing origin pte - 1 to pte_unmap_unlock seems like not a good idea. queue_pages_pte_range can run in MPOL_MF_MOVE_ALL mode which doesn't migrate misplaced pages but returns with EIO when encountering such a page. Since commit a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified") and early break on the first pte in the range results in pte_unmap_unlock on an underflow pte. This can lead to lockups later on when somebody tries to lock the pte resp. page_table_lock again.. Fixes: a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified") Signed-off-by: Shijie Luo Signed-off-by: Miaohe Lin Signed-off-by: Andrew Morton Reviewed-by: Oscar Salvador Acked-by: Michal Hocko Cc: Miaohe Lin Cc: Feilong Lin Cc: Shijie Luo Cc: Link: https://lkml.kernel.org/r/20201019074853.50856-1-luoshijie1@huawei.com Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/mempolicy.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index a2be65bf5d8cc..2f443767fd1b4 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -487,7 +487,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr, struct queue_pages *qp = walk->private; unsigned long flags = qp->flags; int nid, ret; - pte_t *pte; + pte_t *pte, *mapped_pte; spinlock_t *ptl; if (pmd_trans_huge(*pmd)) { @@ -515,7 +515,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr, if (pmd_trans_unstable(pmd)) return 0; retry: - pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + mapped_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (; addr != end; pte++, addr += PAGE_SIZE) { if (!pte_present(*pte)) continue; @@ -554,7 +554,7 @@ retry: } else break; } - pte_unmap_unlock(pte - 1, ptl); + pte_unmap_unlock(mapped_pte, ptl); cond_resched(); return addr != end ? -EIO : 0; } -- 2.27.0