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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 B3524C2BA1A for ; Tue, 7 Apr 2020 01:39:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6C0AB20719 for ; Tue, 7 Apr 2020 01:39:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="KObnXzVc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C0AB20719 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 232FC8E0006; Mon, 6 Apr 2020 21:39:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1BCAF8E0001; Mon, 6 Apr 2020 21:39:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0ABAA8E0006; Mon, 6 Apr 2020 21:39:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0088.hostedemail.com [216.40.44.88]) by kanga.kvack.org (Postfix) with ESMTP id E19F08E0001 for ; Mon, 6 Apr 2020 21:39:43 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id A1C9B87F2 for ; Tue, 7 Apr 2020 01:39:43 +0000 (UTC) X-FDA: 76679352246.10.mouth79_54e2c34db8a32 X-HE-Tag: mouth79_54e2c34db8a32 X-Filterd-Recvd-Size: 2783 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 01:39:43 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 194E720644; Tue, 7 Apr 2020 01:39:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586223582; bh=FGE0CiASS4H74Fv60kNs4z4meKqo7Lbq8lu+ziLI3ss=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=KObnXzVcgKqoIE9NBaKjl4jbo2odfyGEhXCBI8/frPvKEwViWXh1tH6IdXCEXePhp sixw+tGl7oEVC1B50d15ns1aWbsvSWINlR9cQ7NWL9tVfsi3Xyj7b4SK2lbQC0/U+o x4Q2d9HF8quUc1xswJJv9jIDWUpzB8mEmRJNh/GI= Date: Mon, 6 Apr 2020 18:39:41 -0700 From: Andrew Morton To: Peter Xu Cc: syzbot , bgeffon@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, torvalds@linux-foundation.org Subject: Re: BUG: unable to handle kernel paging request in kernel_get_mempolicy Message-Id: <20200406183941.38a2e52026e42dbfde239a56@linux-foundation.org> In-Reply-To: <20200407004745.GA48345@xz-x1> References: <0000000000002b25f105a2a3434d@google.com> <20200407004745.GA48345@xz-x1> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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: On Mon, 6 Apr 2020 20:47:45 -0400 Peter Xu wrote: > >From 23800bff6fa346a4e9b3806dc0cfeb74498df757 Mon Sep 17 00:00:00 2001 > From: Peter Xu > Date: Mon, 6 Apr 2020 20:40:13 -0400 > Subject: [PATCH] mm/mempolicy: Allow lookup_node() to handle fatal signal > > lookup_node() uses gup to pin the page and get node information. It > checks against ret>=0 assuming the page will be filled in. However > it's also possible that gup will return zero, for example, when the > thread is quickly killed with a fatal signal. Teach lookup_node() to > gracefully return an error -EFAULT if it happens. > > ... > > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -902,7 +902,10 @@ static int lookup_node(struct mm_struct *mm, unsigned long addr) > > int locked = 1; > err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked); > - if (err >= 0) { > + if (err == 0) { > + /* E.g. GUP interupted by fatal signal */ > + err = -EFAULT; > + } else if (err > 0) { > err = page_to_nid(p); > put_page(p); > } Doh. Thanks. Should it have been -EINTR?