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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD892C4332F for ; Wed, 6 Apr 2022 00:21:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235716AbiDEXyG (ORCPT ); Tue, 5 Apr 2022 19:54:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354825AbiDEKQJ (ORCPT ); Tue, 5 Apr 2022 06:16:09 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3AC26C954; Tue, 5 Apr 2022 03:03:03 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2785B616E7; Tue, 5 Apr 2022 10:03:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1534EC385A2; Tue, 5 Apr 2022 10:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649152982; bh=rMkDyMAy8tgZhH5NoxgtKM/qQKn45VbcqeVtM9To590=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XU3z7/xBlMBv9+JScfsburHoY+ilzEgEEv+iWzo6zRceah95bC8bgh8TABhxRyTRb Fwkp0/DFMDbF6PXLNXkE866flGAsD5WlyLgO9kfTE/AZqJSyGgMX4eNu2R/AeKL6rM +6meoq4Isj24bL0CR23TXFdzOtyH8nWh6rZCw474= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alistair Popple , David Hildenbrand , Mel Gorman , John Hubbard , Zi Yan , Anshuman Khandual , Oscar Salvador , Andrew Morton , Linus Torvalds Subject: [PATCH 5.10 059/599] mm/pages_alloc.c: dont create ZONE_MOVABLE beyond the end of a node Date: Tue, 5 Apr 2022 09:25:53 +0200 Message-Id: <20220405070300.584276718@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070258.802373272@linuxfoundation.org> References: <20220405070258.802373272@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alistair Popple commit ddbc84f3f595cf1fc8234a191193b5d20ad43938 upstream. ZONE_MOVABLE uses the remaining memory in each node. Its starting pfn is also aligned to MAX_ORDER_NR_PAGES. It is possible for the remaining memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not enough room for ZONE_MOVABLE on that node. Unfortunately this condition is not checked for. This leads to zone_movable_pfn[] getting set to a pfn greater than the last pfn in a node. calculate_node_totalpages() then sets zone->present_pages to be greater than zone->spanned_pages which is invalid, as spanned_pages represents the maximum number of pages in a zone assuming no holes. Subsequently it is possible free_area_init_core() will observe a zone of size zero with present pages. In this case it will skip setting up the zone, including the initialisation of free_lists[]. However populated_zone() checks zone->present_pages to see if a zone has memory available. This is used by iterators such as walk_zones_in_node(). pagetypeinfo_showfree() uses this to walk the free_list of each zone in each node, which are assumed to be initialised due to the zone not being empty. As free_area_init_core() never initialised the free_lists[] this results in the following kernel crash when trying to read /proc/pagetypeinfo: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 #461 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 RIP: 0010:pagetypeinfo_show+0x163/0x460 Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82 RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003 RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00 R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000 FS: 00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0 Call Trace: seq_read_iter+0x128/0x460 proc_reg_read_iter+0x51/0x80 new_sync_read+0x113/0x1a0 vfs_read+0x136/0x1d0 ksys_read+0x70/0xf0 __x64_sys_read+0x1a/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae Fix this by checking that the aligned zone_movable_pfn[] does not exceed the end of the node, and if it does skip creating a movable zone on this node. Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com Fixes: 2a1e274acf0b ("Create the ZONE_MOVABLE zone") Signed-off-by: Alistair Popple Acked-by: David Hildenbrand Acked-by: Mel Gorman Cc: John Hubbard Cc: Zi Yan Cc: Anshuman Khandual Cc: Oscar Salvador Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7402,10 +7402,17 @@ restart: out2: /* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */ - for (nid = 0; nid < MAX_NUMNODES; nid++) + for (nid = 0; nid < MAX_NUMNODES; nid++) { + unsigned long start_pfn, end_pfn; + zone_movable_pfn[nid] = roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES); + get_pfn_range_for_nid(nid, &start_pfn, &end_pfn); + if (zone_movable_pfn[nid] >= end_pfn) + zone_movable_pfn[nid] = 0; + } + out: /* restore the node_state */ node_states[N_MEMORY] = saved_node_state;