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=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C99ABC433E7 for ; Mon, 19 Oct 2020 10:50:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A25C22276 for ; Mon, 19 Oct 2020 10:50:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727511AbgJSKuh (ORCPT ); Mon, 19 Oct 2020 06:50:37 -0400 Received: from mx2.suse.de ([195.135.220.15]:54554 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726606AbgJSKuh (ORCPT ); Mon, 19 Oct 2020 06:50:37 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8E6DDB2D8; Mon, 19 Oct 2020 10:50:36 +0000 (UTC) Date: Mon, 19 Oct 2020 12:50:34 +0200 From: Oscar Salvador To: Shijie Luo Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, mhocko@suse.com, linmiaohe@huawei.com, linfeilong@huawei.com Subject: Re: [PATCH] mm: mempolicy: fix potential pte_unmap_unlock pte error Message-ID: <20201019105029.GA18953@linux> References: <20201019074853.50856-1-luoshijie1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201019074853.50856-1-luoshijie1@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 19, 2020 at 03:48:53AM -0400, Shijie Luo wrote: > 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. I think the above is already explained below? > 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 Anyway, LGTM: Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE L3