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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 721B6C33CAF for ; Mon, 20 Jan 2020 02:35:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2ACDF206D7 for ; Mon, 20 Jan 2020 02:35:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mxy3bJRI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2ACDF206D7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A5F856B0598; Sun, 19 Jan 2020 21:35:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A10CD6B0599; Sun, 19 Jan 2020 21:35:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9262E6B059A; Sun, 19 Jan 2020 21:35:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0136.hostedemail.com [216.40.44.136]) by kanga.kvack.org (Postfix) with ESMTP id 7CCB16B0598 for ; Sun, 19 Jan 2020 21:35:47 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 1513A249D for ; Mon, 20 Jan 2020 02:35:47 +0000 (UTC) X-FDA: 76396447134.06.quilt39_6ca52cf575433 X-HE-Tag: quilt39_6ca52cf575433 X-Filterd-Recvd-Size: 4742 Received: from mail-pl1-f194.google.com (mail-pl1-f194.google.com [209.85.214.194]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Mon, 20 Jan 2020 02:35:46 +0000 (UTC) Received: by mail-pl1-f194.google.com with SMTP id a6so12527024plm.3 for ; Sun, 19 Jan 2020 18:35:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=wlt7J6YX/+zJd9kW5sXYOIVVIkX0dlrdrokN/uFDoZw=; b=mxy3bJRI2vIq2veTmVnwjT5q8VSFqnGz8AQlKMCTnT+JDDgo4mDeyrA+fYWdpiW36E j7JvxAOn+JBAO1e2b8sm4l0YSmOWithMnU+S6BLQwnwn2dqYJP3D+ezuNqhYKK88Bjw2 HY4WwdBgdzaQU+76LW42EbhIUp/2+OCz3AMIf8INDkhzROxB6dtMAggCOMkFHdpJuHcD qIV7L1DMP48LfwMsD8FyYycDMJwxVNpEJ/R0MsaLSacRRHgLl32XXUJuKsAVIZkRevOL dM+mafA29AQQ9VkKFMv+ZQym+JItHEY7vV5YhAjh4r0Tya7ceXvVzIgQuZ+nH1PMwh8p mshg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=wlt7J6YX/+zJd9kW5sXYOIVVIkX0dlrdrokN/uFDoZw=; b=hEEine4iP+w/a22vipJo2eB9zt0NwnFF9JWr2UtUxzT1151MoLFypzLQyDuAxe9tXV mF2EOtHRbyVUfj7hOXZOe0T48ALfn2xyKw7/ZQFMx6RO3jAaoY1Tq8r3VZnDCfF+fIGw K+Rfp8iX9a4lSwcIptuiN47DXs8cIIgQzse0uNkJ9PKnwKCBR5k7762+vnMD9tVhtKkX 69+asQttz5b7pUaInTAENei1Gg3ty33babUVAW5CKa89mGScH2SC9N8LXWOUE3AdaNww qPkbsNr17Txjz5n9StMCtg8lhgiu/O6n8tljyc4r3MZsh0QSM0QEIKqZyWwMnO1fgg9P RZ1A== X-Gm-Message-State: APjAAAXz/lft4IX44xvOeXTbsBGMtHtn56nVZ2si19JulFfGmFNFFmmW fNdtBzt7TShYNJtYrrtqM65IRtFnHA== X-Google-Smtp-Source: APXvYqwKdppuo78Bmv4mW597zkYEkcjDo1L3fm2u4vw1ikPyVxK1zADeKN4O/RbMBCnabUd0f7C1Tg== X-Received: by 2002:a17:90b:8c6:: with SMTP id ds6mr20172885pjb.111.1579487745338; Sun, 19 Jan 2020 18:35:45 -0800 (PST) Received: from mylaptop.redhat.com ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id y197sm37574075pfc.79.2020.01.19.18.35.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 19 Jan 2020 18:35:44 -0800 (PST) From: Pingfan Liu To: linux-mm@kvack.org Cc: Pingfan Liu , Andrew Morton , David Hildenbrand , Dan Williams , Oscar Salvador , Michal Hocko , Baoquan He , Qian Cai , kexec@lists.infradead.org, Kazuhito Hagio Subject: [PATCHv2] mm/sparse: reset section's mem_map when fully deactivated Date: Mon, 20 Jan 2020 10:33:14 +0800 Message-Id: <1579487594-28889-1-git-send-email-kernelfans@gmail.com> X-Mailer: git-send-email 2.7.5 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: After commit ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug"), when a mem section is fully deactivated, section_mem_map still records the section's start pfn, which is not used any more and will be reassigned during re-added. In analogy with alloc/free pattern, it is better to clear all fields of section_mem_map. Beside this, it breaks the user space tool "makedumpfile" [1], which makes assumption that a hot-removed section has mem_map as NULL, instead of checking directly against SECTION_MARKED_PRESENT bit. (makedumpfile will be better to change the assumption, and need a patch) The bug can be reproduced on IBM POWERVM by "drmgr -c mem -r -q 5" , trigger a crash, and save vmcore by makedumpfile [1]: makedumpfile, commit e73016540293 ("[v1.6.7] Update version") Signed-off-by: Pingfan Liu To: linux-mm@kvack.org Cc: Andrew Morton Cc: David Hildenbrand Cc: Dan Williams Cc: Oscar Salvador Cc: Michal Hocko Cc: Baoquan He Cc: Qian Cai Cc: kexec@lists.infradead.org Cc: Kazuhito Hagio --- v1 -> v2: make an explicit convertion from NULL to ulong improve commit log mm/sparse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/sparse.c b/mm/sparse.c index 3822ecb..3918fc3 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -789,7 +789,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, ms->usage = NULL; } memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr); - ms->section_mem_map = sparse_encode_mem_map(NULL, section_nr); + ms->section_mem_map = (unsigned long)NULL; } if (section_is_early && memmap) -- 2.7.5