linux-kernel - Re: [PATCH v2 2/3] mm: calculate deferred pages after skipping mirrored memory

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Message-ID: <20180727115645.GA13637@techadventures.net>
Date:   Fri, 27 Jul 2018 13:56:45 +0200
From:   Oscar Salvador <osalvador@...hadventures.net>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        kirill.shutemov@...ux.intel.com, mhocko@...e.com,
        linux-mm@...ck.org, dan.j.williams@...el.com, jack@...e.cz,
        jglisse@...hat.com, jrdr.linux@...il.com, bhe@...hat.com,
        gregkh@...uxfoundation.org, vbabka@...e.cz,
        richard.weiyang@...il.com, dave.hansen@...el.com,
        rientjes@...gle.com, mingo@...nel.org, abdhalee@...ux.vnet.ibm.com,
        mpe@...erman.id.au
Subject: Re: [PATCH v2 2/3] mm: calculate deferred pages after skipping
 mirrored memory

On Thu, Jul 26, 2018 at 03:35:08PM -0400, Pavel Tatashin wrote:
> update_defer_init() should be called only when struct page is about to be
> initialized. Because it counts number of initialized struct pages, but
> there we may skip struct pages if there is some mirrored memory.
> 
> So move, update_defer_init() after checking for mirrored memory.
> 
> Also, rename update_defer_init() to defer_init() and reverse the return
> boolean to emphasize that this is a boolean function, that tells that the
> reset of memmap initialization should be deferred.
> 
> Make this function self-contained: do not pass number of already
> initialized pages in this zone by using static counters.
> 
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
> ---
>  mm/page_alloc.c | 45 +++++++++++++++++++++++++--------------------
>  1 file changed, 25 insertions(+), 20 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 6796dacd46ac..4946c73e549b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -306,24 +306,33 @@ static inline bool __meminit early_page_uninitialised(unsigned long pfn)
>  }
>  
>  /*
> - * Returns false when the remaining initialisation should be deferred until
> + * Returns true when the remaining initialisation should be deferred until
>   * later in the boot cycle when it can be parallelised.
>   */
> -static inline bool update_defer_init(pg_data_t *pgdat,
> -				unsigned long pfn, unsigned long zone_end,
> -				unsigned long *nr_initialised)
> +static bool __meminit
> +defer_init(int nid, unsigned long pfn, unsigned long end_pfn)

Hi Pavel,

maybe I do not understand properly the __init/__meminit macros, but should not
"defer_init" be __init instead of __meminit?
I think that functions marked as __meminit are not freed up, right?

Besides that, this looks good to me:

Reviewed-by: Oscar Salvador <osalvador@...e.de>
-- 
Oscar Salvador
SUSE L3