From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id 76CAA6B0292 for ; Wed, 7 Jun 2017 13:38:04 -0400 (EDT) Received: by mail-qt0-f199.google.com with SMTP id w1so4132746qtg.6 for ; Wed, 07 Jun 2017 10:38:04 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id h187si2599221qkc.171.2017.06.07.10.38.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Jun 2017 10:38:03 -0700 (PDT) Date: Wed, 7 Jun 2017 13:38:00 -0400 (EDT) From: Jerome Glisse Message-ID: <1169495863.31360420.1496857080560.JavaMail.zimbra@redhat.com> In-Reply-To: <20170607170651.exful7yvxvrjaolz@node.shutemov.name> References: <1496846780-17393-1-git-send-email-jglisse@redhat.com> <20170607170325.65ex46hoqjalprnu@black.fi.intel.com> <20170607170651.exful7yvxvrjaolz@node.shutemov.name> Subject: Re: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not freeing pud v2 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Ingo Molnar , Logan Gunthorpe > On Wed, Jun 07, 2017 at 08:03:25PM +0300, Kirill A. Shutemov wrote: > > On Wed, Jun 07, 2017 at 10:46:20AM -0400, jglisse@redhat.com wrote: > > > From: J=C3=A9r=C3=B4me Glisse > > >=20 > > > 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. > > >=20 > > > 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. > > >=20 > > > af2cf278ef4f x86/mm/hotplug: Don't remove PGD entries in > > > remove_pagetable() > > >=20 > > > Changed since v1: > > > - make free_pud() conditional on the number of page table > > > level > > > - improved commit message > > >=20 > > > Signed-off-by: J=C3=A9r=C3=B4me 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(+) > > >=20 > > > 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) > > > =09spin_unlock(&init_mm.page_table_lock); > > > } > > > =20 > > > +/* > > > + * For 4 levels page table we do not want to free puds but for 5 lev= els > > > + * we should free them. This code also need to change to adapt for b= oot > > > + * time switching between 4 and 5 level. > > > + */ > > > +#if CONFIG_PGTABLE_LEVELS =3D=3D 4 > > > +static inline void free_pud_table(pud_t *pud_start, p4d_t *p4d) > > > +{ > > > +} > >=20 > > Just "if (CONFIG_PGTABLE_LEVELS > 4)" before calling free_pud_table(), = but > > okay -- I'll rework it anyway for boot-time switching. >=20 > Err. "if (CONFIG_PGTABLE_LEVELS =3D=3D 4)" obviously. You want me to respawn a v3 or is that good enough until you finish boot time 5 level page table ? Cheers, J=C3=A9r=C3=B4me -- 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