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=-15.8 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,SPF_HELO_NONE,SPF_PASS,URIBL_RED 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 BCCDFC11F69 for ; Thu, 1 Jul 2021 01:50:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7534C6105A for ; Thu, 1 Jul 2021 01:50:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7534C6105A 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 F1B338D020F; Wed, 30 Jun 2021 21:50:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ECABC8D0202; Wed, 30 Jun 2021 21:50:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D92B98D020F; Wed, 30 Jun 2021 21:50:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0150.hostedemail.com [216.40.44.150]) by kanga.kvack.org (Postfix) with ESMTP id B745E8D0202 for ; Wed, 30 Jun 2021 21:50:23 -0400 (EDT) Received: from smtpin37.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 969A4252D7 for ; Thu, 1 Jul 2021 01:50:23 +0000 (UTC) X-FDA: 78312339126.37.B5E3AD3 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf07.hostedemail.com (Postfix) with ESMTP id 5FB6610004CD for ; Thu, 1 Jul 2021 01:50:23 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id EA0AE61468; Thu, 1 Jul 2021 01:50:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1625104222; bh=1at29HZqa4xcbE0QkL8RimpRBMUAwriLfuBiCNL1g4M=; h=Date:From:To:Subject:In-Reply-To:From; b=Ny7HHTjs78yCRkIbWdb56tiilMMclpPAsiw9Pz3tLqdf95ZiLU/3dhYmJp5txR0lm yXu0aoF5RlNGL1Lrinzk4vQ8ngnAmmHzgXFP1F1H2nI3tBVZb2zFMmD1fLl4YZzxSu GL0xsrId7IhUnAaTFLVWrmEevTHIZSTGcd3/pIDY= Date: Wed, 30 Jun 2021 18:50:21 -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 059/192] fs/proc/kcore: use page_offline_(freeze|thaw) Message-ID: <20210701015021.y4sXmyoGE%akpm@linux-foundation.org> In-Reply-To: <20210630184624.9ca1937310b0dd5ce66b30e7@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5FB6610004CD X-Stat-Signature: 6p5yk3o6qmk8p6u9btdmewbah59n74z5 Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=Ny7HHTjs; dmarc=none; spf=pass (imf07.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-HE-Tag: 1625104223-723301 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: use page_offline_(freeze|thaw) Let's properly synchronize with drivers that set PageOffline(). Unfreeze/thaw every now and then, so drivers that want to set PageOffline() can make progress. Link: https://lkml.kernel.org/r/20210526093041.8800-7-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Mike Rapoport Reviewed-by: Oscar Salvador Cc: Aili Yao Cc: Alexey Dobriyan Cc: Alex Shi Cc: Haiyang Zhang Cc: Jason Wang Cc: Jiri Bohac Cc: "K. Y. Srinivasan" Cc: "Matthew Wilcox (Oracle)" Cc: "Michael S. Tsirkin" Cc: Michal Hocko Cc: Mike Kravetz Cc: Naoya Horiguchi Cc: Roman Gushchin Cc: Stephen Hemminger Cc: Steven Price Cc: Wei Liu Signed-off-by: Andrew Morton --- fs/proc/kcore.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/fs/proc/kcore.c~fs-proc-kcore-use-page_offline_freezethaw +++ a/fs/proc/kcore.c @@ -313,6 +313,7 @@ read_kcore(struct file *file, char __use { char *buf = file->private_data; size_t phdrs_offset, notes_offset, data_offset; + size_t page_offline_frozen = 1; size_t phdrs_len, notes_len; struct kcore_list *m; size_t tsz; @@ -322,6 +323,11 @@ read_kcore(struct file *file, char __use int ret = 0; down_read(&kclist_lock); + /* + * Don't race against drivers that set PageOffline() and expect no + * further page access. + */ + page_offline_freeze(); get_kcore_size(&nphdr, &phdrs_len, ¬es_len, &data_offset); phdrs_offset = sizeof(struct elfhdr); @@ -480,6 +486,12 @@ read_kcore(struct file *file, char __use } } + if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) { + page_offline_thaw(); + cond_resched(); + page_offline_freeze(); + } + if (&m->list == &kclist_head) { if (clear_user(buffer, tsz)) { ret = -EFAULT; @@ -565,6 +577,7 @@ skip: } out: + page_offline_thaw(); up_read(&kclist_lock); if (ret) return ret; _