From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751524AbdFGREA (ORCPT ); Wed, 7 Jun 2017 13:04:00 -0400 Received: from mga11.intel.com ([192.55.52.93]:24255 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751393AbdFGRD7 (ORCPT ); Wed, 7 Jun 2017 13:03:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,311,1493708400"; d="scan'208";a="1179528484" Date: Wed, 7 Jun 2017 20:03:25 +0300 From: "Kirill A. Shutemov" To: jglisse@redhat.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Ingo Molnar , Logan Gunthorpe Subject: Re: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not freeing pud v2 Message-ID: <20170607170325.65ex46hoqjalprnu@black.fi.intel.com> References: <1496846780-17393-1-git-send-email-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1496846780-17393-1-git-send-email-jglisse@redhat.com> User-Agent: NeoMutt/20161126 (1.7.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 07, 2017 at 10:46:20AM -0400, jglisse@redhat.com wrote: > 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) > +{ > +} Just "if (CONFIG_PGTABLE_LEVELS > 4)" before calling free_pud_table(), but okay -- I'll rework it anyway for boot-time switching. -- Kirill A. Shutemov