linux-kernel - Re: [PATCH v9 03/12] mm: deferred_init

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Message-ID: <fc4ef789-d9a8-5dab-6508-f0fe8751b462@oracle.com>
Date:   Tue, 3 Oct 2017 11:15:54 -0400
From:   Pasha Tatashin <pasha.tatashin@...cle.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-kernel@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        x86@...nel.org, kasan-dev@...glegroups.com, borntraeger@...ibm.com,
        heiko.carstens@...ibm.com, davem@...emloft.net,
        willy@...radead.org, ard.biesheuvel@...aro.org,
        mark.rutland@....com, will.deacon@....com, catalin.marinas@....com,
        sam@...nborg.org, mgorman@...hsingularity.net,
        steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        bob.picco@...cle.com
Subject: Re: [PATCH v9 03/12] mm: deferred_init_memmap improvements

Hi Michal,

> 
> Please be explicit that this is possible only because we discard
> memblock data later after 3010f876500f ("mm: discard memblock data
> later"). Also be more explicit how the new code works.

OK

> 
> I like how the resulting code is more compact and smaller.

That was the goal :)

> for_each_free_mem_range also looks more appropriate but I really detest
> the DEFERRED_FREE thingy. Maybe we can handle all that in a single goto
> section. I know this is not an art but manipulating variables from
> macros is more error prone and much more ugly IMHO.

Sure, I can re-arrange to have a goto place. Function won't be as small, 
and if compiler is not smart enough we might end up with having more 
branches than what my current code has.

> 
> please do not use macros. Btw. this deserves its own fix. I suspect that
> no CONFIG_HOLES_IN_ZONE arch enables DEFERRED_STRUCT_PAGE_INIT but
> purely from the review point of view it should be its own patch.

Sure, I will submit this patch separately from the rest of the project. 
In my opinion DEFERRED_STRUCT_PAGE_INIT is the way of the future, so we 
should make sure it is working with as many configs as possible.

Thank you,
Pasha