From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f69.google.com (mail-oi0-f69.google.com [209.85.218.69]) by kanga.kvack.org (Postfix) with ESMTP id 97BD06B0506 for ; Tue, 11 Jul 2017 10:00:39 -0400 (EDT) Received: by mail-oi0-f69.google.com with SMTP id i21so34817oib.0 for ; Tue, 11 Jul 2017 07:00:39 -0700 (PDT) Received: from NAM01-BY2-obe.outbound.protection.outlook.com (mail-by2nam01on0109.outbound.protection.outlook.com. [104.47.34.109]) by mx.google.com with ESMTPS id q128si15150oic.246.2017.07.11.07.00.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 11 Jul 2017 07:00:36 -0700 (PDT) From: "Zi Yan" Subject: Re: [PATCH v8 05/10] mm: thp: enable thp migration in generic path Date: Tue, 11 Jul 2017 10:00:30 -0400 Message-ID: In-Reply-To: <20170711064736.GB22052@hori1.linux.bs1.fc.nec.co.jp> References: <20170701134008.110579-1-zi.yan@sent.com> <20170701134008.110579-6-zi.yan@sent.com> <20170711064736.GB22052@hori1.linux.bs1.fc.nec.co.jp> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=_MailMate_8804FA40-CC25-4A55-BF3B-6B4A404F8436_="; micalg=pgp-sha512; protocol="application/pgp-signature" Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: "kirill.shutemov@linux.intel.com" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "minchan@kernel.org" , "vbabka@suse.cz" , "mgorman@techsingularity.net" , "mhocko@kernel.org" , "khandual@linux.vnet.ibm.com" , "dnellans@nvidia.com" , "dave.hansen@intel.com" This is an OpenPGP/MIME signed message (RFC 3156 and 4880). --=_MailMate_8804FA40-CC25-4A55-BF3B-6B4A404F8436_= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On 11 Jul 2017, at 2:47, Naoya Horiguchi wrote: > On Sat, Jul 01, 2017 at 09:40:03AM -0400, Zi Yan wrote: >> From: Zi Yan >> >> This patch adds thp migration's core code, including conversions >> between a PMD entry and a swap entry, setting PMD migration entry, >> removing PMD migration entry, and waiting on PMD migration entries. >> >> This patch makes it possible to support thp migration. >> If you fail to allocate a destination page as a thp, you just split >> the source thp as we do now, and then enter the normal page migration.= >> If you succeed to allocate destination thp, you enter thp migration. >> Subsequent patches actually enable thp migration for each caller of >> page migration by allowing its get_new_page() callback to >> allocate thps. >> >> ChangeLog v1 -> v2: >> - support pte-mapped thp, doubly-mapped thp >> >> Signed-off-by: Naoya Horiguchi >> >> ChangeLog v2 -> v3: >> - use page_vma_mapped_walk() >> - use pmdp_huge_clear_flush() instead of pmdp_huge_get_and_clear() in >> set_pmd_migration_entry() >> >> ChangeLog v3 -> v4: >> - factor out the code of removing pte pgtable page in zap_huge_pmd() >> >> ChangeLog v4 -> v5: >> - remove unnecessary PTE-mapped THP code in remove_migration_pmd() >> and set_pmd_migration_entry() >> - restructure the code in zap_huge_pmd() to avoid factoring out >> the pte pgtable page code >> - in zap_huge_pmd(), check that PMD swap entries are migration entries= >> - change author information >> >> ChangeLog v5 -> v7 >> - use macro to disable the code when thp migration is not enabled >> >> ChangeLog v7 -> v8 >> - use IS_ENABLED instead of macro to make code look clean in >> zap_huge_pmd() and page_vma_mapped_walk() >> - remove BUILD_BUG() in pmd_to_swp_entry() and swp_entry_to_pmd() to >> avoid compilation error >> - rename variable 'migration' to 'flush_needed' and invert the logic i= n >> zap_huge_pmd() to make code more descriptive >> - use pmdp_invalidate() in set_pmd_migration_entry() to avoid race >> with MADV_DONTNEED >> - remove unnecessary tlb flush in remove_migration_pmd() >> - add the missing migration flag check in page_vma_mapped_walk() >> >> Signed-off-by: Zi Yan >> Cc: Kirill A. Shutemov >> --- >> arch/x86/include/asm/pgtable_64.h | 2 + >> include/linux/swapops.h | 67 ++++++++++++++++++++++++++++++= - >> mm/huge_memory.c | 84 ++++++++++++++++++++++++++++++= ++++++--- >> mm/migrate.c | 32 ++++++++++++++- >> mm/page_vma_mapped.c | 18 +++++++-- >> mm/pgtable-generic.c | 3 +- >> mm/rmap.c | 13 ++++++ >> 7 files changed, 207 insertions(+), 12 deletions(-) >> > ... > >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 91948fbbb0bb..b28f633cd569 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1302,6 +1302,7 @@ static bool try_to_unmap_one(struct page *page, = struct vm_area_struct *vma, >> bool ret =3D true; >> enum ttu_flags flags =3D (enum ttu_flags)arg; >> >> + >> /* munlock has nothing to gain from examining un-locked vmas */ >> if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED)) >> return true; >> @@ -1312,6 +1313,18 @@ static bool try_to_unmap_one(struct page *page,= struct vm_area_struct *vma, >> } >> >> while (page_vma_mapped_walk(&pvmw)) { >> +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION >> + /* PMD-mapped THP migration entry */ >> + if (flags & TTU_MIGRATION) { > > My testing based on mmotm-2017-07-06-16-18 showed that migrating shmem = thp > caused kernel crash. I don't think this is critical because that case i= s > just not-prepared yet. So in order to avoid the crash, please add > PageAnon(page) check here. This makes shmem thp migration just fail. > > + if (!PageAnon(page)) > + continue; > Thanks for your testing. I will add this check in my next version. >> + if (!pvmw.pte && page) { > > Just from curiosity, do we really need this page check? > try_to_unmap() always passes down the parameter 'page' to try_to_unmap_= one() > via rmap_walk_* family, so I think we can assume page is always non-NUL= L. You are right. Checking page is not necessary here. I will remove it in m= y next version. -- Best Regards Yan Zi --=_MailMate_8804FA40-CC25-4A55-BF3B-6B4A404F8436_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQEcBAEBCgAGBQJZZNn+AAoJEEGLLxGcTqbMMv0IAJAb91WfGug4UFMxLmIs5rCV Wkq5adDVyRLYJ1MGqip/AfkPkT0aQjQD3xW40JxW1z3FrsJ6X5HZksh9kLCUvu9W OTjJ0Fj94n67sP7pt1gYUwTLZ3Rga5v9fBc7g0kKa58g2BPdaXZCLpqjV1X8mIW9 X5bAVPvoDZ903850ncykP3u08PKvtf4MEFtixK/TUe8XO+MDACR14g5CfPjYYoI0 DrhA9VDB7o2Eg/0GqNHDN36/Vs5e/mOOQ9UkuaV9ZQrKCMLhi1P9jVVEwBFBsZmi 2I03ke2KsLneK1dXrw41NndD4jvsmazCIpGP25/6KuCCI0mQ7MRp5D1ztplJBzc= =eW63 -----END PGP SIGNATURE----- --=_MailMate_8804FA40-CC25-4A55-BF3B-6B4A404F8436_=-- -- 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/ . 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