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[195.135.220.15]) by mx.google.com with ESMTPS id 37si206329edz.124.2019.05.08.16.15.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 May 2019 16:15:52 -0700 (PDT) Received-SPF: pass (google.com: domain of osalvador@suse.de designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of osalvador@suse.de designates 195.135.220.15 as permitted sender) smtp.mailfrom=osalvador@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 7B7EAAF0C; Wed, 8 May 2019 23:15:51 +0000 (UTC) Message-ID: <1557357332.3028.42.camel@suse.de> Subject: Re: [PATCH v8 09/12] mm/sparsemem: Support sub-section hotplug From: Oscar Salvador To: Dan Williams , akpm@linux-foundation.org Cc: Michal Hocko , Vlastimil Babka , Logan Gunthorpe , Pavel Tatashin , linux-nvdimm@lists.01.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Thu, 09 May 2019 01:15:32 +0200 In-Reply-To: <155718601407.130019.14248061058774128227.stgit@dwillia2-desk3.amr.corp.intel.com> References: <155718596657.130019.17139634728875079809.stgit@dwillia2-desk3.amr.corp.intel.com> <155718601407.130019.14248061058774128227.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit 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 Mon, 2019-05-06 at 16:40 -0700, Dan Williams wrote: > @@ -741,49 +895,31 @@ int __meminit sparse_add_section(int nid, > unsigned long start_pfn, > unsigned long nr_pages, struct vmem_altmap *altmap) > { > unsigned long section_nr = pfn_to_section_nr(start_pfn); > - struct mem_section_usage *usage; > struct mem_section *ms; > struct page *memmap; > int ret; I already pointed this out in v7, but: > > - /* > - * no locking for this, because it does its own > - * plus, it does a kmalloc > - */ > ret = sparse_index_init(section_nr, nid); > if (ret < 0 && ret != -EEXIST) > return ret; sparse_index_init() only returns either -ENOMEM or 0, so the above can be: if (ret < 0) or if (ret) > - ret = 0; > - memmap = populate_section_memmap(start_pfn, > PAGES_PER_SECTION, nid, > - altmap); > - if (!memmap) > - return -ENOMEM; > - usage = kzalloc(mem_section_usage_size(), GFP_KERNEL); > - if (!usage) { > - depopulate_section_memmap(start_pfn, > PAGES_PER_SECTION, altmap); > - return -ENOMEM; > - } > > - ms = __pfn_to_section(start_pfn); > - if (ms->section_mem_map & SECTION_MARKED_PRESENT) { > - ret = -EEXIST; > - goto out; > - } > + memmap = section_activate(nid, start_pfn, nr_pages, altmap); > + if (IS_ERR(memmap)) > + return PTR_ERR(memmap); > + ret = 0; If we got here, sparse_index_init must have returned 0, so ret already contains 0. We can remove the assignment. > > /* > * Poison uninitialized struct pages in order to catch > invalid flags > * combinations. > */ > - page_init_poison(memmap, sizeof(struct page) * > PAGES_PER_SECTION); > + page_init_poison(pfn_to_page(start_pfn), sizeof(struct page) > * nr_pages); > > + ms = __pfn_to_section(start_pfn); > section_mark_present(ms); > - sparse_init_one_section(ms, section_nr, memmap, usage); > + sparse_init_one_section(ms, section_nr, memmap, ms->usage); > > -out: > - if (ret < 0) { > - kfree(usage); > - depopulate_section_memmap(start_pfn, > PAGES_PER_SECTION, altmap); > - } > + if (ret < 0) > + section_deactivate(start_pfn, nr_pages, nid, > altmap); AFAICS, ret is only set by the return code from sparse_index_init, so we cannot really get to this code being ret different than 0. So we can remove the above two lines. I will start reviewing the patches that lack review from this version soon. -- Oscar Salvador SUSE L3