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 44B50C65BAE for ; Thu, 13 Dec 2018 03:46:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E01152075B for ; Thu, 13 Dec 2018 03:46:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="brwX1yRS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E01152075B 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 S1726720AbeLMDqS (ORCPT ); Wed, 12 Dec 2018 22:46:18 -0500 Received: from mail-ed1-f68.google.com ([209.85.208.68]:41190 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726298AbeLMDqS (ORCPT ); Wed, 12 Dec 2018 22:46:18 -0500 Received: by mail-ed1-f68.google.com with SMTP id z28so828137edi.8 for ; Wed, 12 Dec 2018 19:46:17 -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=W2Op4q2i6IeFtZKnnfZX1g7DkK5MbUhuuO4q/S70Hks=; b=brwX1yRSmSBELcW95N7/esKUFzJ8W68yaTeAOxk4tg1PE807xm9G+Rdu4mhLRoDm/F U02bG1U94Md8VUDUHWSLXaOIV54oArCrfsNzhHonxPfHb34gFa96fJWbJlXi5VnpKrMo bfP0yReCYAIqRRmKXrwqHu5qyaVknqsCejiGcqDvT6uS7ax1F6G1hhbEjXSVaRII1rF4 0EkvFoRU4Ryr/Y6LNWXXHjjx3Hnz1M07aIJl98a6UwZe/DpmeYknxo03ootk8YLdo3YV /9RYYouPP6F2VhFMWPcEUZvUVku9kXD8Gl7jLxqB9ZzoICgk8Im9u6uqrcCpBIJEoOX+ RJvg== 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=W2Op4q2i6IeFtZKnnfZX1g7DkK5MbUhuuO4q/S70Hks=; b=E9RUeZvUvJqgu82ysG9rh0ew6jzuFJbozXIwa3JJ5Oh8ufVNTcQl2S3EYElCGV50Ed Fb9afW0gmSHXzJviNJ3mPxvI8kL4+OALZrvGCnkmuuVBvUN52Ohz6iqPO1jBIQoLBLnj 4p2cx5PznA3UN2PszVd1ccPXXFCdfdRuXb7rIY2yeuMUiaO+w83uELg4Do9FlGwGxQsi yAwPl85/9L1VAa1fOoRKdwwotywnwx48Bw+rHShN3x3IpaabK61iXAJmBLVgPq/ciylb ePSaLkQDXcj7QL0LHZqcN52+81OYeXQfs9xCjyIzvQCfwn/0EygYQi2WLuNq5L0+b8eK skIg== X-Gm-Message-State: AA+aEWaISfPd5+5lOx8A4kthzssoVh7ZThbK0RwsqtHPLZLe+hB9O9Co lfMJpQfvPfuHxHcPpsum9v7NrK4N X-Google-Smtp-Source: AFSGD/W/4BQ2DsEkEPsvKEGT0Y3u9RdUGEwvgf86+cp5AbNWXVubumoBn7QitYIlaVqd7Um+ZaVhHg== X-Received: by 2002:a17:906:b387:: with SMTP id o7-v6mr16927718ejz.124.1544672776452; Wed, 12 Dec 2018 19:46:16 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id t24sm273661edb.7.2018.12.12.19.46.15 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 12 Dec 2018 19:46:15 -0800 (PST) Date: Thu, 13 Dec 2018 03:46:15 +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 v2 1/1] mm, memory_hotplug: Initialize struct pages for the full memory section Message-ID: <20181213034615.4ntpo4cl2oo5mcx4@master> Reply-To: Wei Yang References: <20181212172712.34019-1-zaslonko@linux.ibm.com> <20181212172712.34019-2-zaslonko@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181212172712.34019-2-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 Wed, Dec 12, 2018 at 06:27:12PM +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: > >Here are the the panic examples: > CONFIG_DEBUG_VM=y > CONFIG_DEBUG_VM_PGFLAGS=y > > kernel parameter mem=2050M > -------------------------- > 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 > > kernel parameter mem=3075M > -------------------------- > page:000003d08300c000 is uninitialized and poisoned > page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) > Call Trace: > ([<000000000038596c>] is_mem_section_removable+0xb4/0x190) > [<00000000008f12fa>] show_mem_removable+0x9a/0xd8 > [<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: > [<000000000038596c>] is_mem_section_removable+0xb4/0x190 > Kernel panic - not syncing: Fatal exception: panic_on_oops > >Fix the problem by initializing the last memory section of each 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 | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > >diff --git a/mm/page_alloc.c b/mm/page_alloc.c >index 2ec9cc407216..e2afdb2dc2c5 100644 >--- a/mm/page_alloc.c >+++ b/mm/page_alloc.c >@@ -5542,6 +5542,18 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, > cond_resched(); > } > } >+#ifdef CONFIG_SPARSEMEM >+ /* >+ * If the zone does not span 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). >+ */ >+ while (end_pfn % PAGES_PER_SECTION) { >+ __init_single_page(pfn_to_page(end_pfn), end_pfn, zone, nid); >+ end_pfn++; >+ } >+#endif > } What will happen if the end_pfn is PAGES_PER_SECTION aligned, but there is invalid pfn? For example, the page is skipped in the for loop of memmap_init_zone()? > > #ifdef CONFIG_ZONE_DEVICE >-- >2.16.4 -- Wei Yang Help you, Help me