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;
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
From:   Qian Cai <cai@lca.pw>
Mime-Version: 1.0 (1.0)
Subject: Re: [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages()
Date:   Thu, 3 Oct 2019 07:50:31 -0400
Message-Id: <983E7EA4-A022-448C-B11D-8C10441A2E07@lca.pw>
References: <d3a88afd-63c6-1091-cf4c-75cd10b7f547@arm.com>
Cc:     linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Oscar Salvador <osalvador@suse.de>,
        Mel Gorman <mgorman@techsingularity.net>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Pavel Tatashin <pavel.tatashin@microsoft.com>,
        linux-kernel@vger.kernel.org
In-Reply-To: <d3a88afd-63c6-1091-cf4c-75cd10b7f547@arm.com>
To:     Anshuman Khandual <Anshuman.Khandual@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Oct 3, 2019, at 7:31 AM, Anshuman Khandual <Anshuman.Khandual@arm.com> w=
rote:
>=20
> Ohh, never meant that the 'Reserved' bit is anything special here but it
> is a reason to make a page unmovable unlike many other flags.

But dump_page() is used everywhere, and it is better to reserve =E2=80=9Crea=
son=E2=80=9D to indicate something more important rather than duplicating th=
e page flags.

Especially, it is trivial enough right now for developers look in the page f=
lags dumping from has_unmovable_pages(), and figure out the exact branching i=
n the code.=