From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Yang Date: Wed, 05 Feb 2020 22:56:33 +0000 Subject: Re: [PATCH v6 08/10] mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() Message-Id: <20200205225633.GA28446@richard> List-Id: References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-9-david@redhat.com> <20200205095924.GC24162@richard> <20200205144811.GF26758@MiWiFi-R3L-srv> In-Reply-To: <20200205144811.GF26758@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Baoquan He Cc: linux-s390@vger.kernel.org, x86@kernel.org, linux-ia64@vger.kernel.org, Pavel Tatashin , David Hildenbrand , linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Wei Yang , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Dan Williams , linux-arm-kernel@lists.infradead.org, Oscar Salvador On Wed, Feb 05, 2020 at 10:48:11PM +0800, Baoquan He wrote: >Hi Wei Yang, > >On 02/05/20 at 05:59pm, Wei Yang wrote: >> >diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> >index f294918f7211..8dafa1ba8d9f 100644 >> >--- a/mm/memory_hotplug.c >> >+++ b/mm/memory_hotplug.c >> >@@ -393,6 +393,9 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, >> > if (pfn) { >> > zone->zone_start_pfn = pfn; >> > zone->spanned_pages = zone_end_pfn - pfn; >> >+ } else { >> >+ zone->zone_start_pfn = 0; >> >+ zone->spanned_pages = 0; >> > } >> > } else if (zone_end_pfn = end_pfn) { >> > /* >> >@@ -405,34 +408,11 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, >> > start_pfn); >> > if (pfn) >> > zone->spanned_pages = pfn - zone_start_pfn + 1; >> >+ else { >> >+ zone->zone_start_pfn = 0; >> >+ zone->spanned_pages = 0; >> >+ } >> > } >> >> If it is me, I would like to take out these two similar logic out. > >I also like this style. >> >> For example: >> >> if () { >> } else if () { >> } else { >> goto out; >Here the last else is unnecessary, right? > I am afraid not. If the range is not the first or last, we would leave pfn not initialized. -- Wei Yang Help you, Help me