From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f71.google.com (mail-oi0-f71.google.com [209.85.218.71]) by kanga.kvack.org (Postfix) with ESMTP id 16A8C6B0003 for ; Wed, 11 Jul 2018 21:22:41 -0400 (EDT) Received: by mail-oi0-f71.google.com with SMTP id r186-v6so37636390oie.16 for ; Wed, 11 Jul 2018 18:22:41 -0700 (PDT) Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com. [183.91.158.132]) by mx.google.com with ESMTP id e194-v6si13224808oic.415.2018.07.11.18.22.37 for ; Wed, 11 Jul 2018 18:22:39 -0700 (PDT) Date: Thu, 12 Jul 2018 09:19:54 +0800 From: Chao Fan Subject: Re: Bug report about KASLR and ZONE_MOVABLE Message-ID: <20180712011954.GC6742@localhost.localdomain> References: <20180711094244.GA2019@localhost.localdomain> <20180711104158.GE2070@MiWiFi-R3L-srv> <20180711104944.GG1969@MiWiFi-R3L-srv> <20180711124008.GF2070@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20180711124008.GF2070@MiWiFi-R3L-srv> Sender: owner-linux-mm@kvack.org List-ID: To: Baoquan He Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, yasu.isimatu@gmail.com, keescook@chromium.org, indou.takao@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com, douly.fnst@cn.fujitsu.com, mhocko@suse.com, vbabka@suse.cz, mgorman@techsingularity.net, fanc.fnst@cn.fujitsu.com On Wed, Jul 11, 2018 at 08:40:08PM +0800, Baoquan He wrote: >Please try this v3 patch: > >>From 9850d3de9c02e570dc7572069a9749a8add4c4c7 Mon Sep 17 00:00:00 2001 >From: Baoquan He >Date: Wed, 11 Jul 2018 20:31:51 +0800 >Subject: [PATCH v3] mm, page_alloc: find movable zone after kernel text > >In find_zone_movable_pfns_for_nodes(), when try to find the starting >PFN movable zone begins in each node, kernel text position is not >considered. KASLR may put kernel after which movable zone begins. > >Fix it by finding movable zone after kernel text on that node. > >Signed-off-by: Baoquan He >--- > mm/page_alloc.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > >diff --git a/mm/page_alloc.c b/mm/page_alloc.c >index 1521100..390eb35 100644 >--- a/mm/page_alloc.c >+++ b/mm/page_alloc.c >@@ -6547,7 +6547,7 @@ static unsigned long __init early_calculate_totalpages(void) > static void __init find_zone_movable_pfns_for_nodes(void) > { > int i, nid; >- unsigned long usable_startpfn; >+ unsigned long usable_startpfn, real_startpfn; > unsigned long kernelcore_node, kernelcore_remaining; > /* save the state before borrow the nodemask */ > nodemask_t saved_node_state = node_states[N_MEMORY]; >@@ -6681,10 +6681,20 @@ static void __init find_zone_movable_pfns_for_nodes(void) > if (start_pfn >= end_pfn) > continue; Hi Baoquan, Thanks for your quick reply and PATCH. I think it can work well after reviewing the code. But I think the new variable 'real_startpfn' is unnecessary. How about this: diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6d00f746c2fd..0fc9c4283947 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6492,6 +6492,10 @@ static void __init find_zone_movable_pfns_for_nodes(void) if (start_pfn >= end_pfn) continue; + if (pfn_to_nid(PFN_UP(_etext)) == i) + usable_startpfn = max(usable_startpfn, + PFN_UP(_etext)); + /* Account for what is only usable for kernelcore */ if (start_pfn < usable_startpfn) { unsigned long kernel_pages; I think the logic of these two method are the same, and this method change less code. If I am wrong, please let me know. Thanks, Chao Fan > >+ /* >+ * KASLR may put kernel near tail of node memory, >+ * start after kernel on that node to find PFN >+ * which zone begins. >+ */ >+ if (pfn_to_nid(PFN_UP(_etext)) == i) >+ real_startpfn = max(usable_startpfn, >+ PFN_UP(_etext)) >+ else >+ real_startpfn = usable_startpfn; > /* Account for what is only usable for kernelcore */ >- if (start_pfn < usable_startpfn) { >+ if (start_pfn < real_startpfn) { > unsigned long kernel_pages; >- kernel_pages = min(end_pfn, usable_startpfn) >+ kernel_pages = min(end_pfn, real_startpfn) > - start_pfn; > > kernelcore_remaining -= min(kernel_pages, >@@ -6693,7 +6703,7 @@ static void __init find_zone_movable_pfns_for_nodes(void) > required_kernelcore); > > /* Continue if range is now fully accounted */ >- if (end_pfn <= usable_startpfn) { >+ if (end_pfn <= real_startpfn) { > > /* > * Push zone_movable_pfn to the end so >@@ -6704,7 +6714,7 @@ static void __init find_zone_movable_pfns_for_nodes(void) > zone_movable_pfn[nid] = end_pfn; > continue; > } >- start_pfn = usable_startpfn; >+ start_pfn = real_startpfn; > } > > /* >-- >2.1.0 > > >