From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8CBC0C433FF for ; Mon, 12 Aug 2019 20:05:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 49B10208C2 for ; Mon, 12 Aug 2019 20:05:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 49B10208C2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D96A86B0005; Mon, 12 Aug 2019 16:05:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D48AD6B0006; Mon, 12 Aug 2019 16:05:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C0F0E6B0007; Mon, 12 Aug 2019 16:05:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0228.hostedemail.com [216.40.44.228]) by kanga.kvack.org (Postfix) with ESMTP id 9E4966B0005 for ; Mon, 12 Aug 2019 16:05:28 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 0AE898248AA1 for ; Mon, 12 Aug 2019 20:05:28 +0000 (UTC) X-FDA: 75814855536.18.scent41_2f8e88ed7955f X-HE-Tag: scent41_2f8e88ed7955f X-Filterd-Recvd-Size: 10586 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Mon, 12 Aug 2019 20:05:26 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B27CBC0022F1; Mon, 12 Aug 2019 20:05:25 +0000 (UTC) Received: from [10.36.116.42] (ovpn-116-42.ams2.redhat.com [10.36.116.42]) by smtp.corp.redhat.com (Postfix) with ESMTP id 78F061000182; Mon, 12 Aug 2019 20:05:15 +0000 (UTC) Subject: Re: [RFC][Patch v12 1/2] mm: page_reporting: core infrastructure To: Alexander Duyck , Nitesh Narayan Lal Cc: kvm list , LKML , linux-mm , virtio-dev@lists.oasis-open.org, Paolo Bonzini , lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, Yang Zhang , Rik van Riel , "Michael S. Tsirkin" , dodgen@google.com, Konrad Rzeszutek Wilk , dhildenb@redhat.com, Andrea Arcangeli , john.starks@microsoft.com, Dave Hansen , Michal Hocko , cohuck@redhat.com References: <20190812131235.27244-1-nitesh@redhat.com> <20190812131235.27244-2-nitesh@redhat.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: Date: Mon, 12 Aug 2019 22:05:14 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 12 Aug 2019 20:05:25 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: >> --- >> include/linux/mmzone.h | 11 ++ >> include/linux/page_reporting.h | 63 +++++++ >> mm/Kconfig | 6 + >> mm/Makefile | 1 + >> mm/page_alloc.c | 42 ++++- >> mm/page_reporting.c | 332 ++++++++++++++++++++++++++++++++= + >> 6 files changed, 448 insertions(+), 7 deletions(-) >> create mode 100644 include/linux/page_reporting.h >> create mode 100644 mm/page_reporting.c >> >> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >> index d77d717c620c..ba5f5b508f25 100644 >> --- a/include/linux/mmzone.h >> +++ b/include/linux/mmzone.h >> @@ -559,6 +559,17 @@ struct zone { >> /* Zone statistics */ >> atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS]; >> atomic_long_t vm_numa_stat[NR_VM_NUMA_STAT_ITEMS]; >> +#ifdef CONFIG_PAGE_REPORTING >> + /* Pointer to the bitmap in PAGE_REPORTING_MIN_ORDER granulari= ty */ >> + unsigned long *bitmap; >> + /* Preserve start and end PFN in case they change due to hotpl= ug */ >> + unsigned long base_pfn; >> + unsigned long end_pfn; >> + /* Free pages of granularity PAGE_REPORTING_MIN_ORDER */ >> + atomic_t free_pages; >> + /* Number of bits required in the bitmap */ >> + unsigned long nbits; >> +#endif >> } ____cacheline_internodealigned_in_smp; >=20 > Okay, so the original thing this patch set had going for it was that > it was non-invasive. However, now you are adding a bunch of stuff to > the zone. That kind of loses the non-invasive argument for this patch > set compared to mine. >=20 Adding something to "struct zone" is certainly less invasive than core buddy modifications, just saying (I agree that this is suboptimal. I would have guessed that all that's needed is a pointer to some private structure here). However, the migratetype thingy below looks fishy to me. > If we are going to continue further with this patch set then it might > be worth looking into dynamically allocating the space you need for > this block. At a minimum you could probably look at making the bitmap > an RCU based setup so you could define the base and end along with the > bitmap. It would probably help to resolve the hotplug issues you still > need to address. Yeah, I guess that makes sense. [...] >> + >> +static int process_free_page(struct page *page, >> + struct page_reporting_config *phconf, int= count) >> +{ >> + int mt, order, ret =3D 0; >> + >> + mt =3D get_pageblock_migratetype(page); >> + order =3D page_private(page); >> + ret =3D __isolate_free_page(page, order); >> + I just started looking into the wonderful world of isolation/compaction/migration. I don't think saving/restoring the migratetype is correct here. AFAIK, MOVABLE/UNMOVABLE/RECLAIMABLE is just a hint, doesn't mean that e.g., movable pages and up in UNMOVABLE or ordinary kernel allocations on MOVABLE. So that shouldn't be an issue - I guess. 1. You should never allocate something that is no MOVABLE/UNMOVABLE/RECLAIMABLE. Especially not, if you have ISOLATE or CMA here. There should at least be a !is_migrate_isolate_page() check somewhere 2. set_migratetype_isolate() takes the zone lock, so to avoid racing with isolation code, you have to hold the zone lock. Your code seems to do that, so at least you cannot race against isolation. 3. You could end up temporarily allocating something in the ZONE_MOVABLE. The pages you allocate are, however, not movable. There would have to be a way to make alloc_contig_range()/offlining code properly wait until the pages have been processed. Not sure about the real implications, though - too many details in the code (I wonder if Alex' series has a way of dealing with that) When you restore the migratetype, you could suddenly overwrite e.g., ISOLATE, which feels wrong. [...] > So as per your comments in the cover page, the two functions above > should also probably be plugged into the zone resizing logic somewhere > so if a zone is resized the bitmap is adjusted. >=20 >> +/** >> + * zone_reporting_init - For each zone initializes the page reporting= fields >> + * and allocates the respective bitmap. >> + * >> + * This function returns 0 on successful initialization, -ENOMEM othe= rwise. >> + */ >> +static int zone_reporting_init(void) >> +{ >> + struct zone *zone; >> + int ret; >> + >> + for_each_populated_zone(zone) { >> +#ifdef CONFIG_ZONE_DEVICE >> + /* we can not report pages which are not in the buddy = */ >> + if (zone_idx(zone) =3D=3D ZONE_DEVICE) >> + continue; >> +#endif >=20 > I'm pretty sure this isn't needed since I don't think the ZONE_DEVICE > zone will be considered "populated". >=20 I think you are right (although it's confusing, we will have present sections part of a zone but the zone has no present_pages - screams like a re factoring - leftover from ZONE_DEVICE introduction). --=20 Thanks, David / dhildenb