linux-kernel - Re: [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable

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Message-Id: <285C0297-BF27-4095-87B6-AFC88C1F3C0F@lca.pw>
Date:   Thu, 3 Oct 2019 07:19:15 -0400
From:   Qian Cai <cai@....pw>
To:     Anshuman Khandual <Anshuman.Khandual@....com>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Oscar Salvador <osalvador@...e.de>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Pavel Tatashin <pavel.tatashin@...rosoft.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages()



> On Oct 3, 2019, at 5:32 AM, Anshuman Khandual <Anshuman.Khandual@....com> wrote:
> 
> Even though page flags does contain reserved bit information, the problem
> is that we are explicitly printing the reason for this page dump. In this
> case it is caused by the fact that it is a reserved page.
> 
> page dumped because: <reason>
> 
> The proposed change makes it explicit that the dump is caused because a
> non movable page with reserved bit set. It also helps in differentiating 
> between reserved bit condition and the last one "if (found > count)".

Then, someone later would like to add a reason for every different page flags just because they *think* they are special.