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[209.132.183.28]) by mx.google.com with ESMTPS id u198si2182840qka.181.2019.01.29.02.03.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 29 Jan 2019 02:03:59 -0800 (PST) Received-SPF: pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5808CC7A07; Tue, 29 Jan 2019 10:03:58 +0000 (UTC) Received: from [10.36.118.12] (unknown [10.36.118.12]) by smtp.corp.redhat.com (Postfix) with ESMTP id EC295176AE; Tue, 29 Jan 2019 10:03:56 +0000 (UTC) Subject: Re: [PATCH] mm,memory_hotplug: Fix scan_movable_pages for gigantic hugepages To: Andrew Morton , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, mhocko@suse.com References: <20190122154407.18417-1-osalvador@suse.de> <5368e2b4-5aca-40dd-fe18-67d861a04a29@redhat.com> <20190125075830.6mqw2io4rwz7wxx5@d104.suse.de> <20190128145309.c7dcf075b469d6a54694327d@linux-foundation.org> <20190128145617.069b3a5436fc7e34bdebb104@linux-foundation.org> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <20190128145617.069b3a5436fc7e34bdebb104@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 29 Jan 2019 10:03:58 +0000 (UTC) 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 28.01.19 23:56, Andrew Morton wrote: > On Mon, 28 Jan 2019 14:53:09 -0800 Andrew Morton wrote: > >> On Fri, 25 Jan 2019 08:58:33 +0100 Oscar Salvador wrote: >> >>> On Wed, Jan 23, 2019 at 11:33:56AM +0100, David Hildenbrand wrote: >>>> If you use {} for the else case, please also do so for the if case. >>> >>> Diff on top: >>> >>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>> index 25aee4f04a72..d5810e522b72 100644 >>> --- a/mm/memory_hotplug.c >>> +++ b/mm/memory_hotplug.c >>> @@ -1338,9 +1338,9 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) >>> struct page *head = compound_head(page); >>> >>> if (hugepage_migration_supported(page_hstate(head)) && >>> - page_huge_active(head)) >>> + page_huge_active(head)) { >>> return pfn; >>> - else { >>> + } else { >>> unsigned long skip; >>> >>> skip = (1 << compound_order(head)) - (page - head); >>> >> >> The indenting is getting a bit deep also, so how about this? >> >> static unsigned long scan_movable_pages(unsigned long start, unsigned long end) >> { >> unsigned long pfn; >> >> for (pfn = start; pfn < end; pfn++) { >> struct page *page, *head; >> >> if (!pfn_valid(pfn)) >> continue; >> page = pfn_to_page(pfn); >> if (PageLRU(page)) >> return pfn; >> if (__PageMovable(page)) >> return pfn; >> >> if (!PageHuge(page)) >> continue; >> head = compound_head(page); >> if (hugepage_migration_supported(page_hstate(head)) && >> page_huge_active(head)) { >> return pfn; > > checkpatch pointed out that else-after-return isn't needed so we can do > > static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > { > unsigned long pfn; > > for (pfn = start; pfn < end; pfn++) { > struct page *page, *head; > unsigned long skip; > > if (!pfn_valid(pfn)) > continue; > page = pfn_to_page(pfn); > if (PageLRU(page)) > return pfn; > if (__PageMovable(page)) > return pfn; > > if (!PageHuge(page)) > continue; > head = compound_head(page); > if (hugepage_migration_supported(page_hstate(head)) && > page_huge_active(head)) > return pfn; > skip = (1 << compound_order(head)) - (page - head); > pfn += skip - 1; > } > return 0; > } > > --- a/mm/memory_hotplug.c~mmmemory_hotplug-fix-scan_movable_pages-for-gigantic-hugepages-fix > +++ a/mm/memory_hotplug.c > @@ -1305,28 +1305,27 @@ int test_pages_in_a_zone(unsigned long s > static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > { > unsigned long pfn; > - struct page *page; > + > for (pfn = start; pfn < end; pfn++) { > - if (pfn_valid(pfn)) { > - page = pfn_to_page(pfn); > - if (PageLRU(page)) > - return pfn; > - if (__PageMovable(page)) > - return pfn; > - if (PageHuge(page)) { > - struct page *head = compound_head(page); > + struct page *page, *head; > + unsigned long skip; > > - if (hugepage_migration_supported(page_hstate(head)) && > - page_huge_active(head)) > - return pfn; > - else { > - unsigned long skip; > + if (!pfn_valid(pfn)) > + continue; > + page = pfn_to_page(pfn); > + if (PageLRU(page)) > + return pfn; > + if (__PageMovable(page)) > + return pfn; > > - skip = (1 << compound_order(head)) - (page - head); > - pfn += skip - 1; > - } > - } > - } > + if (!PageHuge(page)) > + continue; > + head = compound_head(page); > + if (hugepage_migration_supported(page_hstate(head)) && > + page_huge_active(head)) > + return pfn; > + skip = (1 << compound_order(head)) - (page - head); > + pfn += skip - 1; Not sure if encoding the -1 in the previous line is even better now that we have more space skip = (1 << compound_order(head)) - (page - head + 1); Looks good to me. > } > return 0; > } > _ > -- Thanks, David / dhildenb