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[140.211.169.12]) by mx.google.com with ESMTPS id m188si15900035pfb.266.2019.01.28.14.56.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jan 2019 14:56:18 -0800 (PST) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) client-ip=140.211.169.12; Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 72A7619DB; Mon, 28 Jan 2019 22:56:18 +0000 (UTC) Date: Mon, 28 Jan 2019 14:56:17 -0800 From: Andrew Morton To: Oscar Salvador , David Hildenbrand , linux-mm@kvack.org, linux-kernel@vger.kernel.org, mhocko@suse.com Subject: Re: [PATCH] mm,memory_hotplug: Fix scan_movable_pages for gigantic hugepages Message-Id: <20190128145617.069b3a5436fc7e34bdebb104@linux-foundation.org> In-Reply-To: <20190128145309.c7dcf075b469d6a54694327d@linux-foundation.org> References: <20190122154407.18417-1-osalvador@suse.de> <5368e2b4-5aca-40dd-fe18-67d861a04a29@redhat.com> <20190125075830.6mqw2io4rwz7wxx5@d104.suse.de> <20190128145309.c7dcf075b469d6a54694327d@linux-foundation.org> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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, 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; } return 0; } _