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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 357E1C43334 for ; Fri, 17 Jun 2022 07:43:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BE0A86B0071; Fri, 17 Jun 2022 03:43:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B90606B0073; Fri, 17 Jun 2022 03:43:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A09A86B0074; Fri, 17 Jun 2022 03:43:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 8ED5B6B0071 for ; Fri, 17 Jun 2022 03:43:40 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 64C0960A3A for ; Fri, 17 Jun 2022 07:43:40 +0000 (UTC) X-FDA: 79586938200.26.CB6D3F8 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf26.hostedemail.com (Postfix) with ESMTP id 01EC81400A4 for ; Fri, 17 Jun 2022 07:43:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655451819; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7ReX5+Tea9DeNVBMZAkITRir8x1EyrdX1TO+zxwb4MY=; b=i6Vn7faY1MeTEdTpMheWFCIC7Kx0SEhuiBEGslJvc1tN1H0xhtv7ddTzQY6PU1KW/efDrG KlM+//nfmX7iIUl7BtAwJjdlJbEJSTdQvjrY1MZJsTgZqSarwcNN0zNBJYTitECMlYSKN3 hTaBxDlRGOU/oN9tFEP4ABWS5CTU4NE= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-355-of-pVTx5OPmOYwvW-PJekg-1; Fri, 17 Jun 2022 03:43:36 -0400 X-MC-Unique: of-pVTx5OPmOYwvW-PJekg-1 Received: by mail-wr1-f71.google.com with SMTP id n7-20020adfc607000000b0021a37d8f93aso740349wrg.21 for ; Fri, 17 Jun 2022 00:43:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:organization:in-reply-to :content-transfer-encoding; bh=7ReX5+Tea9DeNVBMZAkITRir8x1EyrdX1TO+zxwb4MY=; b=TKTpluLuJSBt8pRcGkVus92O2WGGkFeIUnAuS5aTUrpzJIYbmwAxNUbiyYvc2tRR/G vDtIeSmEPrMCdEIS7K4x23qgnSHJKpp+1nYyy97vh4Fy0a2mS8BDhY3vGgM3jWU9j6HR LbpQsSGirTR10vi8SC08sIDxMAKNcATEzfFTglOMC1diRiKoRQPF0eHjp/bKnMYvVHcN kjTxjELGv+kPCjSD3Ynz3QBXDnvMqoy9G2SfdyjAikSU8Pj0bTCT/dWuuD+2FuwGKmUZ FEbTmk37VUCmHxH4tGRZpd0fmQl53yAqSr7lJxamv/0cRx4zMNjX5EqVAjlbHfzEpFCQ Vvcg== X-Gm-Message-State: AJIora+mOOnULK0KwyaEha8b2GXxBvs6bSLxR4Ufp+KOur9ROoB/IDd+ wWjjcUP92OHM7u7TnP/N57NYI58xUOrLd3vKgSaRaYzKoG66xAQJpuhJAniFmdVO8uHvpjw/f9i KShrqeYgd0Q8= X-Received: by 2002:a05:600c:1c88:b0:39d:7299:e295 with SMTP id k8-20020a05600c1c8800b0039d7299e295mr8647675wms.155.1655451815082; Fri, 17 Jun 2022 00:43:35 -0700 (PDT) X-Google-Smtp-Source: AGRyM1uMuSqagueU9Uty34908kiFQvwzEaIjUHGQED46YbY0HAP5x4mQF32qlzPwNjwllIDuTBStrQ== X-Received: by 2002:a05:600c:1c88:b0:39d:7299:e295 with SMTP id k8-20020a05600c1c8800b0039d7299e295mr8647654wms.155.1655451814763; Fri, 17 Jun 2022 00:43:34 -0700 (PDT) Received: from ?IPV6:2003:cb:c70a:7e00:bb5b:b526:5b76:5824? (p200300cbc70a7e00bb5bb5265b765824.dip0.t-ipconnect.de. [2003:cb:c70a:7e00:bb5b:b526:5b76:5824]) by smtp.gmail.com with ESMTPSA id o20-20020a1c7514000000b0039c4ec6fdacsm4549519wmc.40.2022.06.17.00.43.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 17 Jun 2022 00:43:34 -0700 (PDT) Message-ID: <186924ab-651f-71a1-93d2-3500a67dffee@redhat.com> Date: Fri, 17 Jun 2022 09:43:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v2 2/2] mm: memory_hotplug: introduce SECTION_CANNOT_OPTIMIZE_VMEMMAP To: Oscar Salvador Cc: Muchun Song , corbet@lwn.net, akpm@linux-foundation.org, paulmck@kernel.org, mike.kravetz@oracle.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com, smuchun@gmail.com References: <20220520025538.21144-1-songmuchun@bytedance.com> <20220520025538.21144-3-songmuchun@bytedance.com> <53024884-0182-df5f-9ca2-00652c64ce36@redhat.com> <24d5ec20-9c9e-93aa-11f4-c4619f51f7d1@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655451820; a=rsa-sha256; cv=none; b=VPdR7kjQ6wwTsyeOjqCRDnLPjBMlZE514rXrHmKg6bsZ63Ac4YWWJS3zU1D95kIUGQ0oI0 weplDz7rtKTgqIihOD6/T6/0LdrUDYxfLudvhbMY755a7b8baqNUWLMlEoSLU666l6bfab kQmHxeoTDrbZgeylUKZsJxyFSI7bch0= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=i6Vn7faY; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf26.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655451820; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=7ReX5+Tea9DeNVBMZAkITRir8x1EyrdX1TO+zxwb4MY=; b=lw0RcgbXX66Rcj41r5o85PNoCPmcY4BVpxcKWKIibvFgMbGc+H98j96XUSKMLePeisn73l ptu+/dMWMI9JmbN90PBK0H+utbpqUQmn/tPkYx6wjXTDxF7VcKGDcUo1u0oRfZJWjce31z SEfmG5TT3MEHqd/LjkC5vzpa3qPamrs= X-Rspamd-Queue-Id: 01EC81400A4 X-Rspam-User: Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=i6Vn7faY; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf26.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=david@redhat.com X-Rspamd-Server: rspam06 X-Stat-Signature: 7443i6f1hayu1chwsbe7ustp9u8zyzrt X-HE-Tag: 1655451819-63942 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: On 17.06.22 07:46, Oscar Salvador wrote: > On Thu, Jun 16, 2022 at 09:30:33AM +0200, David Hildenbrand wrote: >> IIRC, that was used to skip these patches on the offlining path before >> we provided the ranges to offline_pages(). > > Yeah, it was designed for that purpose back then. > >> I'd not mess with PG_reserved, and give them a clearer name, to not >> confuse them with other, ordinary, vmemmap pages that are not >> self-hosted (maybe in the future we might want to flag all vmemmap pages >> with a new type?). > > Not sure whether a new type is really needed, or to put it another way, I > cannot see the benefit. > >> >> I'd just try reusing the flag PG_owner_priv_1. And eventually, flag all >> (v)memmap pages with a type PG_memmap. However, the latter would be >> optional and might not be strictly required >> >> >> So what think could make sense is >> >> /* vmemmap pages that are self-hosted and cannot be optimized/freed. */ >> PG_vmemmap_self_hosted = PG_owner_priv_1, > > Sure, I just lightly tested the below, and seems to work, but not sure > whether that is what you are referring to. > @Munchun: thoughts? > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index e66f7aa3191d..a4556afd7bda 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -193,6 +193,11 @@ enum pageflags { > > /* Only valid for buddy pages. Used to track pages that are reported */ > PG_reported = PG_uptodate, > + > +#ifdef CONFIG_MEMORY_HOTPLUG > + /* For self-hosted memmap pages */ > + PG_vmemmap_self_hosted = PG_owner_priv_1, > +#endif > }; > > #define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1) > @@ -628,6 +633,10 @@ PAGEFLAG_FALSE(SkipKASanPoison, skip_kasan_poison) > */ > __PAGEFLAG(Reported, reported, PF_NO_COMPOUND) > > +#ifdef CONFIG_MEMORY_HOTPLUG > +PAGEFLAG(Vmemmap_self_hosted, vmemmap_self_hosted, PF_ANY) VmemmapSelfHosted, then the function names get nicer. > +#endif > + > /* > * On an anonymous page mapped into a user virtual memory area, > * page->mapping points to its anon_vma, not to a struct address_space; > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index 1089ea8a9c98..e2de7ed27e9e 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -101,6 +101,14 @@ void hugetlb_vmemmap_free(struct hstate *h, struct page *head) > { > unsigned long vmemmap_addr = (unsigned long)head; > unsigned long vmemmap_end, vmemmap_reuse, vmemmap_pages; > + struct mem_section *ms = __pfn_to_section(page_to_pfn(head)); > + struct page *memmap; > + > + memmap = sparse_decode_mem_map(ms->section_mem_map, > + pfn_to_section_nr(page_to_pfn(head))); Why can't we check the head page directly? Either I need more coffee or this can be simplified. > + > + if (PageVmemmap_self_hosted(memmap)) Maybe that's the right place for a comment, an ascii art, and how it is safe to only check the first vmemmap page due to alignment restrictions. > + return; > > vmemmap_pages = hugetlb_optimize_vmemmap_pages(h); > if (!vmemmap_pages) > @@ -199,10 +207,10 @@ static struct ctl_table hugetlb_vmemmap_sysctls[] = { > static __init int hugetlb_vmemmap_sysctls_init(void) > { > /* > - * If "memory_hotplug.memmap_on_memory" is enabled or "struct page" > - * crosses page boundaries, the vmemmap pages cannot be optimized. > + * If "struct page" crosses page boundaries, the vmemmap pages cannot > + * be optimized. > */ > - if (!mhp_memmap_on_memory() && is_power_of_2(sizeof(struct page))) > + if (is_power_of_2(sizeof(struct page))) > register_sysctl_init("vm", hugetlb_vmemmap_sysctls); > > return 0; > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 1213d0c67a53..863966c2c6f1 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -45,8 +45,6 @@ > #ifdef CONFIG_MHP_MEMMAP_ON_MEMORY > static int memmap_on_memory_set(const char *val, const struct kernel_param *kp) > { > - if (hugetlb_optimize_vmemmap_enabled()) > - return 0; > return param_set_bool(val, kp); > } > > @@ -1032,6 +1030,7 @@ int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages, > { > unsigned long end_pfn = pfn + nr_pages; > int ret; > + int i; > > ret = kasan_add_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages)); > if (ret) > @@ -1039,6 +1038,12 @@ int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages, > > move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_UNMOVABLE); > > + /* > + * Let us flag self-hosted memmap > + */ I think that comment can be dropped because the code does exactly that. > + for (i = 0; i < nr_pages; i++) > + SetPageVmemmap_self_hosted(pfn_to_page(pfn + i)); > + > /* > * It might be that the vmemmap_pages fully span sections. If that is > * the case, mark those sections online here as otherwise they will be > > -- Thanks, David / dhildenb