Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752229AbdLAJvL (ORCPT ); Fri, 1 Dec 2017 04:51:11 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60706 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752035AbdLAJux (ORCPT ); Fri, 1 Dec 2017 04:50:53 -0500 Date: Fri, 1 Dec 2017 17:50:48 +0800 From: Dave Young To: linux-kernel@vger.kernel.org Cc: pasha.tatashin@oracle.com, linux-mm@kvack.org, akpm@linux-foundation.org, Michal Hocko Subject: [PATCH V2] mm: check pfn_valid first in zero_resv_unavail Message-ID: <20171201095048.GA3084@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.1 (2017-09-22) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 01 Dec 2017 09:50:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3242 Lines: 64 With latest kernel I get below bug while testing kdump: [ 0.000000] BUG: unable to handle kernel paging request at ffffea00034b1040 [ 0.000000] IP: zero_resv_unavail+0xbd/0x126 [ 0.000000] PGD 37b98067 P4D 37b98067 PUD 37b97067 PMD 0 [ 0.000000] Oops: 0002 [#1] SMP [ 0.000000] Modules linked in: [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.15.0-rc1+ #316 [ 0.000000] Hardware name: LENOVO 20ARS1BJ02/20ARS1BJ02, BIOS GJET92WW (2.42 ) 03/03/2017 [ 0.000000] task: ffffffff81a0e4c0 task.stack: ffffffff81a00000 [ 0.000000] RIP: 0010:zero_resv_unavail+0xbd/0x126 [ 0.000000] RSP: 0000:ffffffff81a03d88 EFLAGS: 00010006 [ 0.000000] RAX: 0000000000000000 RBX: ffffea00034b1040 RCX: 0000000000000010 [ 0.000000] RDX: 0000000000000000 RSI: 0000000000000092 RDI: ffffea00034b1040 [ 0.000000] RBP: 00000000000d2c41 R08: 00000000000000c0 R09: 0000000000000a0d [ 0.000000] R10: 0000000000000002 R11: 0000000000007f01 R12: ffffffff81a03d90 [ 0.000000] R13: ffffea0000000000 R14: 0000000000000063 R15: 0000000000000062 [ 0.000000] FS: 0000000000000000(0000) GS:ffffffff81c73000(0000) knlGS:0000000000000000 [ 0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.000000] CR2: ffffea00034b1040 CR3: 0000000037609000 CR4: 00000000000606b0 [ 0.000000] Call Trace: [ 0.000000] ? free_area_init_nodes+0x640/0x664 [ 0.000000] ? zone_sizes_init+0x58/0x72 [ 0.000000] ? setup_arch+0xb50/0xc6c [ 0.000000] ? start_kernel+0x64/0x43d [ 0.000000] ? secondary_startup_64+0xa5/0xb0 [ 0.000000] Code: c1 e8 0c 48 39 d8 76 27 48 89 de 48 c1 e3 06 48 c7 c7 7a 87 79 81 e8 b0 c0 3e ff 4c 01 eb b9 10 00 00 00 31 c0 48 89 df 49 ff c6 ab eb bc 6a 00 49 c7 c0 f0 93 d1 81 31 d2 83 ce ff 41 54 49 [ 0.000000] RIP: zero_resv_unavail+0xbd/0x126 RSP: ffffffff81a03d88 [ 0.000000] CR2: ffffea00034b1040 [ 0.000000] ---[ end trace f5ba9e8f73c7ee26 ]--- This is introduced with commit a4a3ede2132a ("mm: zero reserved and unavailable struct pages") The reason is some efi reserved boot ranges is not reported in E820 ram. In my case it is a bgrt buffer: efi: mem00: [Boot Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x00000000d2c41000-0x00000000d2c85fff] (0MB) Use "add_efi_memmap" can workaround the problem with another fix: http://lkml.kernel.org/r/20171130052327.GA3500@dhcp-128-65.nay.redhat.com In zero_resv_unavail it would be better to check pfn_valid first before zero the page struct. This fixes the problem and potential other similar problems. Also as Pavel Tatashin suggested checks pfn_valid at the beginning of the section. Signed-off-by: Dave Young --- v1->v2: Michal Hocko: patch log improvement Pavel Tatashin: check pfn at the beginning of the section mm/page_alloc.c | 2 ++ 1 file changed, 2 insertions(+) --- linux-x86.orig/mm/page_alloc.c +++ linux-x86/mm/page_alloc.c @@ -6253,6 +6253,8 @@ void __paginginit zero_resv_unavail(void pgcnt = 0; for_each_resv_unavail_range(i, &start, &end) { for (pfn = PFN_DOWN(start); pfn < PFN_UP(end); pfn++) { + if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) + continue; mm_zero_struct_page(pfn_to_page(pfn)); pgcnt++; }