Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 18 Oct 2019 10:55:28 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     David Hildenbrand <david@redhat.com>
Cc:     Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Qian Cai <cai@lca.pw>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: memory offline infinite loop after soft offline
Message-ID: <20191018085528.GG5017@dhcp22.suse.cz>
References: <1570829564.5937.36.camel@lca.pw>
 <20191014083914.GA317@dhcp22.suse.cz>
 <20191017093410.GA19973@hori.linux.bs1.fc.nec.co.jp>
 <20191017100106.GF24485@dhcp22.suse.cz>
 <1571335633.5937.69.camel@lca.pw>
 <20191017182759.GN24485@dhcp22.suse.cz>
 <20191018021906.GA24978@hori.linux.bs1.fc.nec.co.jp>
 <33946728-bdeb-494a-5db8-e279acebca47@redhat.com>
 <20191018082459.GE5017@dhcp22.suse.cz>
 <f065d998-7fa3-ef9a-c2f4-5b9116f5596b@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <f065d998-7fa3-ef9a-c2f4-5b9116f5596b@redhat.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri 18-10-19 10:38:21, David Hildenbrand wrote:
> On 18.10.19 10:24, Michal Hocko wrote:
> > On Fri 18-10-19 10:13:36, David Hildenbrand wrote:
> > [...]
> > > However, if the compound page spans multiple pageblocks
> > 
> > Although hugetlb pages spanning pageblocks are possible this shouldn't
> > matter in__test_page_isolated_in_pageblock because this function doesn't
> > really operate on pageblocks as the name suggests.  It is simply
> > traversing all valid RAM ranges (see walk_system_ram_range).
> 
> As long as the hugepages don't span memory blocks/sections, you are right. I
> have no experience with gigantic pages in this regard.

They can clearly span sections (1GB is larger than 128MB). Why do you
think it matters actually? walk_system_ram_range walks RAM ranges and no
allocation should span holes in RAM right?
-- 
Michal Hocko
SUSE Labs