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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 27EA9C433FE for ; Fri, 11 Dec 2020 22:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8F7A23C83 for ; Fri, 11 Dec 2020 22:39:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406010AbgLKViY (ORCPT ); Fri, 11 Dec 2020 16:38:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:32964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405977AbgLKVh5 (ORCPT ); Fri, 11 Dec 2020 16:37:57 -0500 Date: Fri, 11 Dec 2020 13:36:53 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1607722614; bh=OxdipKPcakqLS2jEp2iuR0I4YoCZzTg0P1U6jh4HFTI=; h=From:To:Subject:In-Reply-To:From; b=aSbcu6pxg0wzXGy/eiBWFCK5x3J4TSkGbtiLXiaKx5QDoj4+k0A2q+PP4vGSByjYv oxp7w5K9QyZBPXNFeqqqGwIIfATiqvJecR4hmdwUZvmRIOWqetFxRwTsVZc7yttcd6 RSMAypTrSRXiO7uCUNXcY9l2r9IlExXvw5DQQ9vw= From: Andrew Morton To: akpm@linux-foundation.org, borntraeger@de.ibm.com, gerald.schaefer@linux.ibm.com, linux-mm@kvack.org, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 8/8] mm/hugetlb: clear compound_nr before freeing gigantic pages Message-ID: <20201211213653.AWzFNUbZK%akpm@linux-foundation.org> In-Reply-To: <20201211133555.88407977f082963499ed343c@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Gerald Schaefer Subject: mm/hugetlb: clear compound_nr before freeing gigantic pages Commit 1378a5ee451a ("mm: store compound_nr as well as compound_order") added compound_nr counter to first tail struct page, overlaying with page->mapping. The overlay itself is fine, but while freeing gigantic hugepages via free_contig_range(), a "bad page" check will trigger for non-NULL page->mapping on the first tail page: [ 276.681603] BUG: Bad page state in process bash pfn:380001 [ 276.681614] page:00000000c35f0856 refcount:0 mapcount:0 mapping:00000000126b68aa index:0x0 pfn:0x380001 [ 276.681620] aops:0x0 [ 276.681622] flags: 0x3ffff00000000000() [ 276.681626] raw: 3ffff00000000000 0000000000000100 0000000000000122 0000000100000000 [ 276.681628] raw: 0000000000000000 0000000000000000 ffffffff00000000 0000000000000000 [ 276.681630] page dumped because: non-NULL mapping [ 276.681632] Modules linked in: [ 276.681637] CPU: 6 PID: 616 Comm: bash Not tainted 5.10.0-rc7-next-20201208 #1 [ 276.681639] Hardware name: IBM 3906 M03 703 (LPAR) [ 276.681641] Call Trace: [ 276.681648] [<0000000458c252b6>] show_stack+0x6e/0xe8 [ 276.681652] [<000000045971cf60>] dump_stack+0x90/0xc8 [ 276.681656] [<0000000458e8b186>] bad_page+0xd6/0x130 [ 276.681658] [<0000000458e8cdea>] free_pcppages_bulk+0x26a/0x800 [ 276.681661] [<0000000458e8e67e>] free_unref_page+0x6e/0x90 [ 276.681663] [<0000000458e8ea6c>] free_contig_range+0x94/0xe8 [ 276.681666] [<0000000458ea5e54>] update_and_free_page+0x1c4/0x2c8 [ 276.681669] [<0000000458ea784e>] free_pool_huge_page+0x11e/0x138 [ 276.681671] [<0000000458ea8530>] set_max_huge_pages+0x228/0x300 [ 276.681673] [<0000000458ea86c0>] nr_hugepages_store_common+0xb8/0x130 [ 276.681678] [<0000000458fd5b6a>] kernfs_fop_write+0xd2/0x218 [ 276.681681] [<0000000458ef9da0>] vfs_write+0xb0/0x2b8 [ 276.681684] [<0000000458efa15c>] ksys_write+0xac/0xe0 [ 276.681687] [<000000045972c5ca>] system_call+0xe6/0x288 [ 276.681730] Disabling lock debugging due to kernel taint This is because only the compound_order is cleared in destroy_compound_gigantic_page(), and compound_nr is set to 1U << order == 1 for order 0 in set_compound_order(page, 0). Fix this by explicitly clearing compound_nr for first tail page after calling set_compound_order(page, 0). Link: https://lkml.kernel.org/r/20201208182813.66391-2-gerald.schaefer@linux.ibm.com Fixes: 1378a5ee451a ("mm: store compound_nr as well as compound_order") Signed-off-by: Gerald Schaefer Reviewed-by: Matthew Wilcox (Oracle) Cc: Mike Kravetz Cc: Christian Borntraeger Cc; Heiko Carstens Cc: [5.9+] Signed-off-by: Andrew Morton --- mm/hugetlb.c | 1 + 1 file changed, 1 insertion(+) --- a/mm/hugetlb.c~mm-hugetlb-clear-compound_nr-before-freeing-gigantic-pages +++ a/mm/hugetlb.c @@ -1216,6 +1216,7 @@ static void destroy_compound_gigantic_pa } set_compound_order(page, 0); + page[1].compound_nr = 0; __ClearPageHead(page); } _