linux-kernel - Re: [PATCH v2] mm: convert page type macros to enum

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Date: Thu, 06 Jun 2024 17:06:27 -0700
From: Stephen Brennan <stephen.s.brennan@...cle.com>
To: David Hildenbrand <david@...hat.com>,
        Andrew Morton
 <akpm@...ux-foundation.org>
Cc: Omar Sandoval <osandov@...ndov.com>, Hao Ge <gehao@...inos.cn>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        "Vishal
 Moola (Oracle)" <vishal.moola@...il.com>, linux-mm@...ck.org,
        linux-debuggers@...r.kernel.org,
        "Matthew Wilcox (Oracle)"
 <willy@...radead.org>
Subject: Re: [PATCH v2] mm: convert page type macros to enum

David Hildenbrand <david@...hat.com> writes:
> On 06.06.24 20:26, Stephen Brennan wrote:
>> Changing PG_slab from a page flag to a page type in commit 46df8e73a4a3
>> ("mm: free up PG_slab") in has the unintended consequence of removing
>> the PG_slab constant from kernel debuginfo. The commit does add the
>> value to the vmcoreinfo note, which allows debuggers to find the value
>> without hardcoding it. However it's most flexible to continue
>> representing the constant with an enum. To that end, convert the page
>> type fields into an enum. Debuggers will now be able to detect that
>> PG_slab's type has changed from enum pageflags to enum page_type.
>> 
>> Fixes: 46df8e73a4a3 ("mm: free up PG_slab")
>> 
>> Signed-off-by: Stephen Brennan <stephen.s.brennan@...cle.com>
>> ---
>> v1 -> v2: include PAGE_TYPE_BASE and PAGE_MAPCOUNT_RESERVE
>
> This has a conflict with mm/mm-unstable.

Thank you, that's what I get for developing on master. I'll send v3
based on mm-unstable once it finishes compiling.

-Stephen