linux-kernel - Re: [RFC] mm/page_alloc: Enumerate bad page reasons

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Message-ID: <20200330123402.GI14243@dhcp22.suse.cz>
Date:   Mon, 30 Mar 2020 14:34:02 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC] mm/page_alloc: Enumerate bad page reasons

On Mon 30-03-20 17:55:14, Anshuman Khandual wrote:
> 
> 
> On 03/30/2020 02:13 PM, Michal Hocko wrote:
> > On Mon 30-03-20 12:21:37, Anshuman Khandual wrote:
> >> Enumerate all existing bad page reasons which can be used in bad_page() for
> >> reporting via __dump_page(). Unfortunately __dump_page() cannot be changed.
> >> __dump_page() is called from dump_page() that accepts a raw string and is
> >> also an exported symbol that is currently being used from various generic
> >> memory functions and other drivers. This reduces code duplication while
> >> reporting bad pages.
> > 
> > I dunno. It sounds like over engineering something that is an internal
> > stuff. Besides that I consider string reasons kinda obvious and I am
> > pretty sure I would have to check them for each numeric alias when want
> > to read the code. Yeah, yeah, nothing really hard but still...
> 
> Right these are very much self explanatory. Would moving these aliases into
> mm/page_alloc.c itself, make it any better for quicker access ?

Not really. Cscopes doesn't really care where it is. It is the fact that
the constant makes to have a look is what makes this not an improvement
from my POV.
 
> > So I am not really sure this is all worth the code churn. Besides
> 
> I understand but is not just repeating the same strings in similar functions
> bit suboptimal as well.

I do not really see why that would be suboptimal.
-- 
Michal Hocko
SUSE Labs