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=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 6B309C433E6 for ; Mon, 31 Aug 2020 07:58:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 566802073A for ; Mon, 31 Aug 2020 07:58:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728164AbgHaH6Z (ORCPT ); Mon, 31 Aug 2020 03:58:25 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:60147 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725829AbgHaH6W (ORCPT ); Mon, 31 Aug 2020 03:58:22 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4Bg2d25dfrz9v46s; Mon, 31 Aug 2020 09:58:14 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id ziN4ogZZ3b0q; Mon, 31 Aug 2020 09:58:14 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4Bg2d24hCCz9v46r; Mon, 31 Aug 2020 09:58:14 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id AB3FD8B79B; Mon, 31 Aug 2020 09:58:19 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id 3qjn3q60cyjq; Mon, 31 Aug 2020 09:58:19 +0200 (CEST) Received: from po17688vm.idsi0.si.c-s.fr (po15451.idsi0.si.c-s.fr [172.25.230.104]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 6E24C8B799; Mon, 31 Aug 2020 09:58:19 +0200 (CEST) Received: by po17688vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 4FCBE65D48; Mon, 31 Aug 2020 07:58:19 +0000 (UTC) Message-Id: From: Christophe Leroy Subject: [PATCH] powerpc: Fix random segfault when freeing hugetlb range To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Date: Mon, 31 Aug 2020 07:58:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following random segfault is observed from time to time with map_hugetlb selftest: root@localhost:~# ./map_hugetlb 1 19 524288 kB hugepages Mapping 1 Mbytes Segmentation fault [ 31.219972] map_hugetlb[365]: segfault (11) at 117 nip 77974f8c lr 779a6834 code 1 in ld-2.23.so[77966000+21000] [ 31.220192] map_hugetlb[365]: code: 9421ffc0 480318d1 93410028 90010044 9361002c 93810030 93a10034 93c10038 [ 31.220307] map_hugetlb[365]: code: 93e1003c 93210024 8123007c 81430038 <80e90004> 814a0004 7f443a14 813a0004 [ 31.221911] BUG: Bad rss-counter state mm:(ptrval) type:MM_FILEPAGES val:33 [ 31.229362] BUG: Bad rss-counter state mm:(ptrval) type:MM_ANONPAGES val:5 This fault is due to hugetlb_free_pgd_range() freeing page tables that are also used by regular pages. As explain in the comment at the beginning of hugetlb_free_pgd_range(), the verification done in free_pgd_range() on floor and ceiling is not done here, which means hugetlb_free_pte_range() can free outside the expected range. As the verification cannot be done in hugetlb_free_pgd_range(), it must be done in hugetlb_free_pte_range(). Fixes: b250c8c08c79 ("powerpc/8xx: Manage 512k huge pages as standard pages.") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy --- arch/powerpc/mm/hugetlbpage.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index 26292544630f..e7ae2a2c4545 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -330,10 +330,24 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif get_hugepd_cache_index(pdshift - shift)); } -static void hugetlb_free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, unsigned long addr) +static void hugetlb_free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, + unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) { + unsigned long start = addr; pgtable_t token = pmd_pgtable(*pmd); + start &= PMD_MASK; + if (start < floor) + return; + if (ceiling) { + ceiling &= PMD_MASK; + if (!ceiling) + return; + } + if (end - 1 > ceiling - 1) + return; + pmd_clear(pmd); pte_free_tlb(tlb, token, addr); mm_dec_nr_ptes(tlb->mm); @@ -363,7 +377,7 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud, */ WARN_ON(!IS_ENABLED(CONFIG_PPC_8xx)); - hugetlb_free_pte_range(tlb, pmd, addr); + hugetlb_free_pte_range(tlb, pmd, addr, end, floor, ceiling); continue; } -- 2.25.0