Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752819AbdGNAH6 convert rfc822-to-8bit (ORCPT ); Thu, 13 Jul 2017 20:07:58 -0400 Received: from tyo161.gate.nec.co.jp ([114.179.232.161]:52720 "EHLO tyo161.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751198AbdGNAH4 (ORCPT ); Thu, 13 Jul 2017 20:07:56 -0400 From: Naoya Horiguchi To: Zi Yan 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" Subject: Re: [PATCH v8 05/10] mm: thp: enable thp migration in generic path Thread-Topic: [PATCH v8 05/10] mm: thp: enable thp migration in generic path Thread-Index: AQHS+hGV5znhtdAGSEOzBurWcUhu6KJOERkAgALZRgCAACDlAIAA090A Date: Fri, 14 Jul 2017 00:06:42 +0000 Message-ID: <20170714000641.GA6588@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> <20170713093040.GA24851@hori1.linux.bs1.fc.nec.co.jp> In-Reply-To: Accept-Language: en-US, ja-JP Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.128.101.4] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <96683CEE4B2A0D489D58F1FD268EC62F@gisp.nec.co.jp> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-TM-AS-MML: disable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5235 Lines: 131 On Thu, Jul 13, 2017 at 07:28:24AM -0400, Zi Yan wrote: > On 13 Jul 2017, at 5:30, Naoya Horiguchi wrote: > > > On Tue, Jul 11, 2017 at 10:00:30AM -0400, Zi Yan wrote: > >> 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 in > >>>> 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 = true; > >>>> enum ttu_flags flags = (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 is > >>> 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. > > > > Sorry, the code I'm suggesting above doesn't work because it makes normal > > pagecache migration fail. This check should come after making sure that > > pvmw.pte is NULL. > > Right. I think the two ifs are confusing. Replacing the chunk with: > > if (!pvmw.pte && (flags & TTU_MIGRATION)) { > VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), > page); > > if (!PageAnon(page)) > continue; > > set_pmd_migration_entry(&pvmw, page); > continue; > } > > would be better. Yes, it looks good. > > BTW, is your page migration test suite available online? If so, I could use > it to test my code. Please refer to https://github.com/Naoya-Horiguchi/mm_regression. Thanks, Naoya Horiguchi