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[195.135.220.15]) by mx.google.com with ESMTPS id gj17si7400982ejb.342.2019.04.17.06.56.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Apr 2019 06:56:36 -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 8794BB177; Wed, 17 Apr 2019 13:56:35 +0000 (UTC) Message-ID: <1555509378.3139.35.camel@suse.de> Subject: Re: [PATCH v1 3/4] mm/memory_hotplug: Make __remove_section() never fail From: Oscar Salvador To: David Hildenbrand , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Michal Hocko , Pavel Tatashin , Qian Cai , Wei Yang , Arun KS , Mathieu Malaterre Date: Wed, 17 Apr 2019 15:56:18 +0200 In-Reply-To: <20190409100148.24703-4-david@redhat.com> References: <20190409100148.24703-1-david@redhat.com> <20190409100148.24703-4-david@redhat.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 Tue, 2019-04-09 at 12:01 +0200, David Hildenbrand wrote: > Let's just warn in case a section is not valid instead of failing to > remove somewhere in the middle of the process, returning an error > that > will be mostly ignored by callers. > > Cc: Andrew Morton > Cc: Oscar Salvador > Cc: Michal Hocko > Cc: David Hildenbrand > Cc: Pavel Tatashin > Cc: Qian Cai > Cc: Wei Yang > Cc: Arun KS > Cc: Mathieu Malaterre > Signed-off-by: David Hildenbrand Just a nit: I think this could be combined with patch#2. The only reason to fail in here is 1) !valid_section 2) !present_section. As I stated in patch#2, one cannot be without the other, so makes sense to rip present_section check from unregister_mem_section() as well. Then, you could combine both changelogs explaining the whole thing, and why we do not need the present_section check either. But the change looks good to me: Reviewed-by: Oscar Salvador > --- > mm/memory_hotplug.c | 22 +++++++++------------- > 1 file changed, 9 insertions(+), 13 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index b0cb05748f99..17a60281c36f 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -517,15 +517,15 @@ static void __remove_zone(struct zone *zone, > unsigned long start_pfn) > pgdat_resize_unlock(zone->zone_pgdat, &flags); > } > > -static int __remove_section(struct zone *zone, struct mem_section > *ms, > - unsigned long map_offset, struct vmem_altmap > *altmap) > +static void __remove_section(struct zone *zone, struct mem_section > *ms, > + unsigned long map_offset, > + struct vmem_altmap *altmap) > { > unsigned long start_pfn; > int scn_nr; > - int ret = -EINVAL; > > - if (!valid_section(ms)) > - return ret; > + if (WARN_ON_ONCE(!valid_section(ms))) > + return; > > unregister_memory_section(ms); > > @@ -534,7 +534,6 @@ static int __remove_section(struct zone *zone, > struct mem_section *ms, > __remove_zone(zone, start_pfn); > > sparse_remove_one_section(zone, ms, map_offset, altmap); > - return 0; > } > > /** > @@ -554,7 +553,7 @@ int __remove_pages(struct zone *zone, unsigned > long phys_start_pfn, > { > unsigned long i; > unsigned long map_offset = 0; > - int sections_to_remove, ret = 0; > + int sections_to_remove; > > /* In the ZONE_DEVICE case device driver owns the memory > region */ > if (is_dev_zone(zone)) { > @@ -575,16 +574,13 @@ int __remove_pages(struct zone *zone, unsigned > long phys_start_pfn, > unsigned long pfn = phys_start_pfn + > i*PAGES_PER_SECTION; > > cond_resched(); > - ret = __remove_section(zone, __pfn_to_section(pfn), > map_offset, > - altmap); > + __remove_section(zone, __pfn_to_section(pfn), > map_offset, > + altmap); > map_offset = 0; > - if (ret) > - break; > } > > set_zone_contiguous(zone); > - > - return ret; > + return 0; > } > #endif /* CONFIG_MEMORY_HOTREMOVE */ > -- Oscar Salvador SUSE L3