From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751503AbdFGOrj (ORCPT ); Wed, 7 Jun 2017 10:47:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51806 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751526AbdFGOq1 (ORCPT ); Wed, 7 Jun 2017 10:46:27 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 939B31766AC Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jglisse@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 939B31766AC From: jglisse@redhat.com To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Andy Lutomirski , Ingo Molnar , "Kirill A . Shutemov" , Logan Gunthorpe Subject: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not freeing pud v2 Date: Wed, 7 Jun 2017 10:46:20 -0400 Message-Id: <1496846780-17393-1-git-send-email-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 07 Jun 2017 14:46:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jérôme Glisse With commit af2cf278ef4f we no longer free pud so that we do not have synchronize all pgd on hotremove/vfree. But the new 5 level page table patchset reverted that for 4 level page table. This patch restore af2cf278ef4f and disable free_pud() if we are in the 4 level page table case thus avoiding BUG_ON() after hot- remove. af2cf278ef4f x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Changed since v1: - make free_pud() conditional on the number of page table level - improved commit message Signed-off-by: Jérôme Glisse Cc: Andy Lutomirski Cc: Ingo Molnar Cc: Kirill A. Shutemov Cc: Logan Gunthorpe > thus we now trigger a BUG_ON() l128 in sync_global_pgds() > > This patch remove free_pud() like in af2cf278ef4f --- arch/x86/mm/init_64.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 95651dc..61028bc 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -771,6 +771,16 @@ static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud) spin_unlock(&init_mm.page_table_lock); } +/* + * For 4 levels page table we do not want to free puds but for 5 levels + * we should free them. This code also need to change to adapt for boot + * time switching between 4 and 5 level. + */ +#if CONFIG_PGTABLE_LEVELS == 4 +static inline void free_pud_table(pud_t *pud_start, p4d_t *p4d) +{ +} +#else /* CONFIG_PGTABLE_LEVELS == 4 */ static void __meminit free_pud_table(pud_t *pud_start, p4d_t *p4d) { pud_t *pud; @@ -788,6 +798,7 @@ static void __meminit free_pud_table(pud_t *pud_start, p4d_t *p4d) p4d_clear(p4d); spin_unlock(&init_mm.page_table_lock); } +#endif /* CONFIG_PGTABLE_LEVELS == 4 */ static void __meminit remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end, -- 2.7.5