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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 48E96C433DF for ; Mon, 19 Oct 2020 07:49:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 81CEE22243 for ; Mon, 19 Oct 2020 07:49:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81CEE22243 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B381A6B005D; Mon, 19 Oct 2020 03:49:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AE9236B0062; Mon, 19 Oct 2020 03:49:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9D7EE6B0068; Mon, 19 Oct 2020 03:49:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0206.hostedemail.com [216.40.44.206]) by kanga.kvack.org (Postfix) with ESMTP id 6E7D96B005D for ; Mon, 19 Oct 2020 03:49:18 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id EF99C180AD811 for ; Mon, 19 Oct 2020 07:49:17 +0000 (UTC) X-FDA: 77387899554.16.wash64_570d64527235 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id C7E6B100C20D9 for ; Mon, 19 Oct 2020 07:49:17 +0000 (UTC) X-HE-Tag: wash64_570d64527235 X-Filterd-Recvd-Size: 3045 Received: from huawei.com (szxga07-in.huawei.com [45.249.212.35]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Mon, 19 Oct 2020 07:49:16 +0000 (UTC) Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id A5084D8C6022345DAAD2; Mon, 19 Oct 2020 15:49:13 +0800 (CST) Received: from huawei.com (10.175.104.175) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.487.0; Mon, 19 Oct 2020 15:49:07 +0800 From: Shijie Luo To: CC: , , , , , , Subject: [PATCH] mm: mempolicy: fix potential pte_unmap_unlock pte error Date: Mon, 19 Oct 2020 03:48:53 -0400 Message-ID: <20201019074853.50856-1-luoshijie1@huawei.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.104.175] X-CFilter-Loop: Reflected Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When flags in queue_pages_pte_range don't have MPOL_MF_MOVE or MPOL_MF_MO= VE_ALL bits, code breaks and passing origin pte - 1 to pte_unmap_unlock seems l= ike not a good idea. queue_pages_pte_range can run in MPOL_MF_MOVE_ALL mode which doesn't migr= ate misplaced pages but returns with EIO when encountering such a page. Since commit a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_M= F_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 w= hen 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 --- mm/mempolicy.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 3fde772ef5ef..3ca4898f3f24 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -525,7 +525,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned= long addr, unsigned long flags =3D qp->flags; int ret; bool has_unmovable =3D false; - pte_t *pte; + pte_t *pte, *mapped_pte; spinlock_t *ptl; =20 ptl =3D pmd_trans_huge_lock(pmd, vma); @@ -539,7 +539,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned= long addr, if (pmd_trans_unstable(pmd)) return 0; =20 - pte =3D pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + mapped_pte =3D pte =3D pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (; addr !=3D end; pte++, addr +=3D PAGE_SIZE) { if (!pte_present(*pte)) continue; @@ -571,7 +571,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned= long addr, } else break; } - pte_unmap_unlock(pte - 1, ptl); + pte_unmap_unlock(mapped_pte, ptl); cond_resched(); =20 if (has_unmovable) --=20 2.19.1