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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT 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 B71F0C43381 for ; Fri, 22 Mar 2019 11:32:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 85E9221917 for ; Fri, 22 Mar 2019 11:32:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553254375; bh=YZDtC6QjCVDCJ1LjcWKT0JHREHmzHilzN3M1mJzB1ZM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MVjhkjWSoQsPrF22SLJNE/Ac21rRdqICkan6uAntAROMq+Loi+ws1DKQZVwDTUgTb TtQqA6OCd9w7AbvwKlVp6IePahjHsDwHZKw13VOGO7+MTJRckrBnSJ547LQNmN9TO4 uIKXLER1DcS2mQ56MfxFoPpXolIAXIHvc4m1Nl90= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730220AbfCVLcy (ORCPT ); Fri, 22 Mar 2019 07:32:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:33178 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730207AbfCVLcv (ORCPT ); Fri, 22 Mar 2019 07:32:51 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 C77D4218B0; Fri, 22 Mar 2019 11:32:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553254370; bh=YZDtC6QjCVDCJ1LjcWKT0JHREHmzHilzN3M1mJzB1ZM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XLhpdVVbrxaWmJ5l9XFUCdB1QUig1mOahZuxn5B2r0PZwVLiqUMuD24dJqePYbqVr qealRkvxGdT9O6NxCwsnCqqznhVMEYz9AUaTI72WXskbnQlT9Zh38DDrsQiGP0fZLS 4vhfllIjjIIPk4n0jasG5YJMraMy8ZYbBdHUlsU4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michal Hocko , Mikhail Zaslonko , Gerald Schaefer , Mikhail Gavrilov , Oscar Salvador , Pavel Tatashin , Heiko Carstens , Martin Schwidefsky , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.4 100/230] mm, memory_hotplug: is_mem_section_removable do not pass the end of a zone Date: Fri, 22 Mar 2019 12:13:58 +0100 Message-Id: <20190322111243.620434971@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111236.796964179@linuxfoundation.org> References: <20190322111236.796964179@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit efad4e475c312456edb3c789d0996d12ed744c13 ] Patch series "mm, memory_hotplug: fix uninitialized pages fallouts", v2. Mikhail Zaslonko has posted fixes for the two bugs quite some time ago [1]. I have pushed back on those fixes because I believed that it is much better to plug the problem at the initialization time rather than play whack-a-mole all over the hotplug code and find all the places which expect the full memory section to be initialized. We have ended up with commit 2830bf6f05fb ("mm, memory_hotplug: initialize struct pages for the full memory section") merged and cause a regression [2][3]. The reason is that there might be memory layouts when two NUMA nodes share the same memory section so the merged fix is simply incorrect. In order to plug this hole we really have to be zone range aware in those handlers. I have split up the original patch into two. One is unchanged (patch 2) and I took a different approach for `removable' crash. [1] http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com [2] https://bugzilla.redhat.com/show_bug.cgi?id=1666948 [3] http://lkml.kernel.org/r/20190125163938.GA20411@dhcp22.suse.cz This patch (of 2): Mikhail has reported the following VM_BUG_ON triggered when reading sysfs removable state of a memory block: page:000003d08300c000 is uninitialized and poisoned page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) Call Trace: is_mem_section_removable+0xb4/0x190 show_mem_removable+0x9a/0xd8 dev_attr_show+0x34/0x70 sysfs_kf_seq_show+0xc8/0x148 seq_read+0x204/0x480 __vfs_read+0x32/0x178 vfs_read+0x82/0x138 ksys_read+0x5a/0xb0 system_call+0xdc/0x2d8 Last Breaking-Event-Address: is_mem_section_removable+0xb4/0x190 Kernel panic - not syncing: Fatal exception: panic_on_oops The reason is that the memory block spans the zone boundary and we are stumbling over an unitialized struct page. Fix this by enforcing zone range in is_mem_section_removable so that we never run away from a zone. Link: http://lkml.kernel.org/r/20190128144506.15603-2-mhocko@kernel.org Signed-off-by: Michal Hocko Reported-by: Mikhail Zaslonko Debugged-by: Mikhail Zaslonko Tested-by: Gerald Schaefer Tested-by: Mikhail Gavrilov Reviewed-by: Oscar Salvador Cc: Pavel Tatashin Cc: Heiko Carstens Cc: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/memory_hotplug.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 0addef5f8aa3..153acbf5f83d 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1358,7 +1358,8 @@ static struct page *next_active_pageblock(struct page *page) int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages) { struct page *page = pfn_to_page(start_pfn); - struct page *end_page = page + nr_pages; + unsigned long end_pfn = min(start_pfn + nr_pages, zone_end_pfn(page_zone(page))); + struct page *end_page = pfn_to_page(end_pfn); /* Check the starting page of each pageblock within the range */ for (; page < end_page; page = next_active_pageblock(page)) { -- 2.19.1