From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id C8C086B0279 for ; Wed, 7 Jun 2017 13:04:08 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id s12so6758806pgc.2 for ; Wed, 07 Jun 2017 10:04:08 -0700 (PDT) Received: from mga07.intel.com (mga07.intel.com. [134.134.136.100]) by mx.google.com with ESMTPS id f3si2237383plb.505.2017.06.07.10.04.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Jun 2017 10:04:07 -0700 (PDT) Date: Wed, 7 Jun 2017 20:03:25 +0300 From: "Kirill A. Shutemov" 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> Sender: owner-linux-mm@kvack.org List-ID: To: jglisse@redhat.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Ingo Molnar , Logan Gunthorpe On Wed, Jun 07, 2017 at 10:46:20AM -0400, jglisse@redhat.com wrote: > From: Jerome 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: Jerome 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 -- 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