From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 6E83F6B0279 for ; Wed, 7 Jun 2017 10:46:28 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id 20so2770567qtq.2 for ; Wed, 07 Jun 2017 07:46:28 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id m56si2156939qtb.270.2017.06.07.07.46.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Jun 2017 07:46:27 -0700 (PDT) From: jglisse@redhat.com 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 Sender: owner-linux-mm@kvack.org List-ID: 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 From: JA(C)rA'me 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: JA(C)rA'me 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org