linux-kernel - Re: [PATCH 2/3] mm: separate memory allocation and actual work in alloc_vmap

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Date:   Fri, 1 Mar 2019 15:43:19 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Roman Gushchin <guroan@...il.com>, linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>, kernel-team@...com,
        Roman Gushchin <guro@...com>
Subject: Re: [PATCH 2/3] mm: separate memory allocation and actual work in
 alloc_vmap_area()

On 2/25/19 9:30 PM, Roman Gushchin wrote:
> alloc_vmap_area() is allocating memory for the vmap_area, and
> performing the actual lookup of the vm area and vmap_area
> initialization.
> 
> This prevents us from using a pre-allocated memory for the map_area
> structure, which can be used in some cases to minimize the number
> of required memory allocations.

Hmm, but that doesn't happen here or in the later patch, right? The only
caller of init_vmap_area() is alloc_vmap_area(). What am I missing?

> Let's keep the memory allocation part in alloc_vmap_area() and
> separate everything else into init_vmap_area().
> 
> Signed-off-by: Roman Gushchin <guro@...com>
> Acked-by: Johannes Weiner <hannes@...xchg.org>
> Reviewed-by: Matthew Wilcox <willy@...radead.org>