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=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_PASS,USER_AGENT_NEOMUTT 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 4E152C04EB8 for ; Mon, 10 Dec 2018 15:10:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 08EFE20672 for ; Mon, 10 Dec 2018 15:10:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="gCZsw/8I" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 08EFE20672 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727873AbeLJPKI (ORCPT ); Mon, 10 Dec 2018 10:10:08 -0500 Received: from mail-ed1-f66.google.com ([209.85.208.66]:36345 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727109AbeLJPKI (ORCPT ); Mon, 10 Dec 2018 10:10:08 -0500 Received: by mail-ed1-f66.google.com with SMTP id f23so9776002edb.3 for ; Mon, 10 Dec 2018 07:10:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=VcRx/sk/JIDgc6qs0A8WB3wEc565b8bdR5XcVGijwTg=; b=gCZsw/8InAGPInFqf0PJGVegDnO11zBooZ09tNLmRx0DVNKk84G3Bp6DHFpqhW4jvY A3Yk0Q1T5N2LuvXLqaF/6qJU5VFKxeA6FUBxJDRna9wlLcmfw/bnTLBEaku3pfrEdkVy HAV9nuHigmKC9i6mq9d/yZnKN0f5AEs0jeQ/rFbyAIqkT1hNFezaX2uf9oCfkmnNrhSU rxcT2V78lRUHyPPwiDqPi12GmNIFAALUYz73i5ucwewlGgWc0M4plLm/NzyerENJuIX1 jNXCyVICpI8nrvVVVwlNwF3G/k9iXOvFMjnSaGi3kujJzSI619XcaHVB2k9gAzHP0uEo 9ilA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=VcRx/sk/JIDgc6qs0A8WB3wEc565b8bdR5XcVGijwTg=; b=s9yDAAmPLOgbhWgwjTDiTffkPeF7UtOjeH2rTJk4z7Et1pYT8XloU3XJ/pSFfsYw02 q6QLdfChQehguaKU1jHXVYNaY5xROGt58b4Fzo2jyKp6l/rT7lAn7ef2A2AQ7FuIL3s1 yWX8KFNhbRnEUp722hxJlmvDrefjxg1+9bANKX9jDFHr0Y4jv/TCrOBRoewISiVoXP9M gbIUw6NkuJnK6+FCobO09v4bOsjFTZu4sj5//y3X95T2vTihmfcgkulumfNGnojT9xW1 jiGMc+dIvIDk9poxbHl8cLAOtSTlk+VlgGr7O/FqBMUG7ffzzVZS3n33aIFGmCo8HHhQ ZgHA== X-Gm-Message-State: AA+aEWaSU6AHQfN5jpWQKgVRZsR1wnYRRItMBMb0ybzZZPl5Kp8+Puts oEEhQYqvL25v6LBmfa76Llk= X-Google-Smtp-Source: AFSGD/WLOm0JHd2RU7ZF/FqE6J0AV+l7wxJhLgAO8TqZB1sZXqfYuu/AYajt6XomYaCxZVP87y8vQg== X-Received: by 2002:a50:fa0c:: with SMTP id b12mr11349611edq.138.1544454606543; Mon, 10 Dec 2018 07:10:06 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id s12sm3434265edb.43.2018.12.10.07.10.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 10 Dec 2018 07:10:05 -0800 (PST) Date: Mon, 10 Dec 2018 15:10:05 +0000 From: Wei Yang To: Mikhail Zaslonko Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, Pavel.Tatashin@microsoft.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, gerald.schaefer@de.ibm.com Subject: Re: [PATCH 1/1] mm, memory_hotplug: Initialize struct pages for the full memory section Message-ID: <20181210151005.xukiibwbb6ohqyex@master> Reply-To: Wei Yang References: <20181210130712.30148-1-zaslonko@linux.ibm.com> <20181210130712.30148-2-zaslonko@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181210130712.30148-2-zaslonko@linux.ibm.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 10, 2018 at 02:07:12PM +0100, Mikhail Zaslonko wrote: >If memory end is not aligned with the sparse memory section boundary, the >mapping of such a section is only partly initialized. This may lead to >VM_BUG_ON due to uninitialized struct page access from >is_mem_section_removable() or test_pages_in_a_zone() function triggered by >memory_hotplug sysfs handlers: > > page:000003d082008000 is uninitialized and poisoned > page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) > Call Trace: > ([<0000000000385b26>] test_pages_in_a_zone+0xde/0x160) > [<00000000008f15c4>] show_valid_zones+0x5c/0x190 > [<00000000008cf9c4>] dev_attr_show+0x34/0x70 > [<0000000000463ad0>] sysfs_kf_seq_show+0xc8/0x148 > [<00000000003e4194>] seq_read+0x204/0x480 > [<00000000003b53ea>] __vfs_read+0x32/0x178 > [<00000000003b55b2>] vfs_read+0x82/0x138 > [<00000000003b5be2>] ksys_read+0x5a/0xb0 > [<0000000000b86ba0>] system_call+0xdc/0x2d8 > Last Breaking-Event-Address: > [<0000000000385b26>] test_pages_in_a_zone+0xde/0x160 > Kernel panic - not syncing: Fatal exception: panic_on_oops > >Fix the problem by initializing the last memory section of the highest zone >in memmap_init_zone() till the very end, even if it goes beyond the zone >end. > >Signed-off-by: Mikhail Zaslonko >Reviewed-by: Gerald Schaefer >Cc: >--- > mm/page_alloc.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > >diff --git a/mm/page_alloc.c b/mm/page_alloc.c >index 2ec9cc407216..41ef5508e5f1 100644 >--- a/mm/page_alloc.c >+++ b/mm/page_alloc.c >@@ -5542,6 +5542,21 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, > cond_resched(); > } > } >+#ifdef CONFIG_SPARSEMEM >+ /* >+ * If there is no zone spanning the rest of the section >+ * then we should at least initialize those pages. Otherwise we >+ * could blow up on a poisoned page in some paths which depend >+ * on full sections being initialized (e.g. memory hotplug). >+ */ >+ if (end_pfn == max_pfn) { >+ while (end_pfn % PAGES_PER_SECTION) { >+ __init_single_page(pfn_to_page(end_pfn), end_pfn, zone, >+ nid); >+ end_pfn++; >+ } >+ } >+#endif If my understanding is correct, end_pfn is not a valid range. memmap_init_zone() initialize the range [start_pfn, start_pfn + size). I am afraid this will break the syntax. And max_pfn is also not a valid one. For example, on x86, update_end_of_memory_vars() will update max_pfn, which is calculated by: end_pfn = PFN_UP(start + size); BTW, as you mentioned this apply to hotplug case. And then why this couldn't happen during boot up? What differ these two cases? > } > > #ifdef CONFIG_ZONE_DEVICE >-- >2.16.4 -- Wei Yang Help you, Help me