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=-9.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,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 2BBF2C43381 for ; Sat, 23 Feb 2019 21:08:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F02802086C for ; Sat, 23 Feb 2019 21:08:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550956113; bh=mpb9MU/ezaiRyvGhc3PViVUm6a8DFRWtxx5dhnJKjx4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Ibq9NSt2IyZosvmU/8LE6d4VJs9CUiuasLk4J1rTjYMO3ejXpoF4PfvI/Py6laBTh K0J6R2F9ud2i7fHhf2sgkQrQDjDO8JDvDpG9MAHY4NzMP2NNddAN+9/rbW/iTEbvwn I2yzyAgDrESu+ee6BTx85TouQNXT7FI2nQE9uuSI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729269AbfBWVIb (ORCPT ); Sat, 23 Feb 2019 16:08:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:43808 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728692AbfBWVI2 (ORCPT ); Sat, 23 Feb 2019 16:08:28 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0405D20861; Sat, 23 Feb 2019 21:08:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550956107; bh=mpb9MU/ezaiRyvGhc3PViVUm6a8DFRWtxx5dhnJKjx4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g2LsDnodEXEfpwqgtM9Wj0hYDH19phf1h3ANe5Mo1Hl07+otMJyk1nKJtnlaTZ1t9 9+KYz7BL7oknaz5o0CZTU6jLia+Z8+2YS5tw0yNtYbN1+AC1cqZ+N48//sligfbZtB M3DWCGaC1QQg6Zt7C3OQuktha4ix7Qt3rV6zYWg4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Michal Hocko , Pavel Tatashin , Heiko Carstens , Martin Schwidefsky , Andrew Morton , Linus Torvalds , Sasha Levin , linux-mm@kvack.org Subject: [PATCH AUTOSEL 4.19 60/65] mm, memory_hotplug: is_mem_section_removable do not pass the end of a zone Date: Sat, 23 Feb 2019 16:06:35 -0500 Message-Id: <20190223210640.200911-60-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190223210640.200911-1-sashal@kernel.org> References: <20190223210640.200911-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Hocko [ 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 c6119ad3561ea..34cde04f346d9 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1258,7 +1258,8 @@ static bool is_pageblock_removable_nolock(struct page *page) bool 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