From patchwork Thu Jul 1 01:50:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12353167 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=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_RED 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 D7A97C11F6A for ; Thu, 1 Jul 2021 01:50:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9049E61241 for ; Thu, 1 Jul 2021 01:50:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9049E61241 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 15F488D0209; Wed, 30 Jun 2021 21:50:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 10FD98D0202; Wed, 30 Jun 2021 21:50:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F19FE8D0209; Wed, 30 Jun 2021 21:50:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0145.hostedemail.com [216.40.44.145]) by kanga.kvack.org (Postfix) with ESMTP id CA5248D0202 for ; Wed, 30 Jun 2021 21:50:05 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A0000181AEF3F for ; Thu, 1 Jul 2021 01:50:05 +0000 (UTC) X-FDA: 78312338370.26.BF2EBFA Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf14.hostedemail.com (Postfix) with ESMTP id 4762B6001AA5 for ; Thu, 1 Jul 2021 01:50:05 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id D626C61468; Thu, 1 Jul 2021 01:50:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1625104204; bh=l0/S+LLQunTS3Zar5n1r2cgGpT8Ax0M5iwOAkUwL3XY=; h=Date:From:To:Subject:In-Reply-To:From; b=sqv76ERwmL46uFLB/6ugHWrV0ac+cG6uzVl5V5N66qFQG0yVXftKIkEmZhiuYWv6v bdDyuxQdBuNpZMLH9tuNO1ob3agu2TmtleNhGtwKhuzU4CxojtrAYs64fx4+Nxhd32 YD2CmtZ5iRCjJfE4Y/JQ8adLXefAcXPSU06GJt3E= Date: Wed, 30 Jun 2021 18:50:03 -0700 From: Andrew Morton To: adobriyan@gmail.com, akpm@linux-foundation.org, alex.shi@linux.alibaba.com, david@redhat.com, guro@fb.com, haiyangz@microsoft.com, jasowang@redhat.com, jbohac@suse.cz, kys@microsoft.com, linux-mm@kvack.org, mhocko@suse.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, mst@redhat.com, naoya.horiguchi@nec.com, osalvador@suse.de, rppt@linux.ibm.com, steven.price@arm.com, sthemmin@microsoft.com, torvalds@linux-foundation.org, wei.liu@kernel.org, willy@infradead.org, yaoaili@kingsoft.com Subject: [patch 054/192] fs/proc/kcore: drop KCORE_REMAP and KCORE_OTHER Message-ID: <20210701015003.2E6L6dEh3%akpm@linux-foundation.org> In-Reply-To: <20210630184624.9ca1937310b0dd5ce66b30e7@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=sqv76ERw; dmarc=none; spf=pass (imf14.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam02 X-Stat-Signature: z7dg3zpic8fgyzsgw4i1wjxkt11t9zir X-Rspamd-Queue-Id: 4762B6001AA5 X-HE-Tag: 1625104205-435049 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: From: David Hildenbrand Subject: fs/proc/kcore: drop KCORE_REMAP and KCORE_OTHER Patch series "fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages", v3. Looking for places where the kernel might unconditionally read PageOffline() pages, I stumbled over /proc/kcore; turns out /proc/kcore needs some more love to not touch some other pages we really don't want to read -- i.e., hwpoisoned ones. Examples for PageOffline() pages are pages inflated in a balloon, memory unplugged via virtio-mem, and partially-present sections in memory added by the Hyper-V balloon. When reading pages inflated in a balloon, we essentially produce unnecessary load in the hypervisor; holes in partially present sections in case of Hyper-V are not accessible and already were a problem for /proc/vmcore, fixed in makedumpfile by detecting PageOffline() pages. In the future, virtio-mem might disallow reading unplugged memory -- marked as PageOffline() -- in some environments, resulting in undefined behavior when accessed; therefore, I'm trying to identify and rework all these (corner) cases. With this series, there is really only access via /dev/mem, /proc/vmcore and kdb left after I ripped out /dev/kmem. kdb is an advanced corner-case use case -- we won't care for now if someone explicitly tries to do nasty things by reading from/writing to physical addresses we better not touch. /dev/mem is a use case we won't support for virtio-mem, at least for now, so we'll simply disallow mapping any virtio-mem memory via /dev/mem next. /proc/vmcore is really only a problem when dumping the old kernel via something that's not makedumpfile (read: basically never), however, we'll try sanitizing that as well in the second kernel in the future. Tested via kcore_dump: https://github.com/schlafwandler/kcore_dump This patch (of 6): Commit db779ef67ffe ("proc/kcore: Remove unused kclist_add_remap()") removed the last user of KCORE_REMAP. Commit 595dd46ebfc1 ("vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page") removed the last user of KCORE_OTHER. Let's drop both types. While at it, also drop vaddr in "struct kcore_list", used by KCORE_REMAP only. Link: https://lkml.kernel.org/r/20210526093041.8800-1-david@redhat.com Link: https://lkml.kernel.org/r/20210526093041.8800-2-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Mike Rapoport Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: Alexey Dobriyan Cc: "Matthew Wilcox (Oracle)" Cc: Oscar Salvador Cc: Michal Hocko Cc: Roman Gushchin Cc: Alex Shi Cc: Steven Price Cc: Mike Kravetz Cc: Aili Yao Cc: Jiri Bohac Cc: "K. Y. Srinivasan" Cc: Haiyang Zhang Cc: Stephen Hemminger Cc: Wei Liu Cc: Naoya Horiguchi Signed-off-by: Andrew Morton --- fs/proc/kcore.c | 7 ++----- include/linux/kcore.h | 3 --- 2 files changed, 2 insertions(+), 8 deletions(-) --- a/fs/proc/kcore.c~fs-proc-kcore-drop-kcore_remap-and-kcore_other +++ a/fs/proc/kcore.c @@ -380,11 +380,8 @@ read_kcore(struct file *file, char __use phdr->p_type = PT_LOAD; phdr->p_flags = PF_R | PF_W | PF_X; phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset; - if (m->type == KCORE_REMAP) - phdr->p_vaddr = (size_t)m->vaddr; - else - phdr->p_vaddr = (size_t)m->addr; - if (m->type == KCORE_RAM || m->type == KCORE_REMAP) + phdr->p_vaddr = (size_t)m->addr; + if (m->type == KCORE_RAM) phdr->p_paddr = __pa(m->addr); else if (m->type == KCORE_TEXT) phdr->p_paddr = __pa_symbol(m->addr); --- a/include/linux/kcore.h~fs-proc-kcore-drop-kcore_remap-and-kcore_other +++ a/include/linux/kcore.h @@ -11,14 +11,11 @@ enum kcore_type { KCORE_RAM, KCORE_VMEMMAP, KCORE_USER, - KCORE_OTHER, - KCORE_REMAP, }; struct kcore_list { struct list_head list; unsigned long addr; - unsigned long vaddr; size_t size; int type; };