linux-kernel - Re: [PATCH v4 2/4] mm/sparsemem: Defer the ms->section_mem

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Message-ID: <39ec4f7c-2ef8-aaef-7034-e1f895eeb283@intel.com>
Date:   Thu, 7 Jun 2018 15:47:05 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Baoquan He <bhe@...hat.com>, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, pagupta@...hat.com
Cc:     linux-mm@...ck.org, kirill.shutemov@...ux.intel.com
Subject: Re: [PATCH v4 2/4] mm/sparsemem: Defer the ms->section_mem_map
 clearing

On 05/21/2018 03:15 AM, Baoquan He wrote:
> In sparse_init(), if CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER=y, system
> will allocate one continuous memory chunk for mem maps on one node and
> populate the relevant page tables to map memory section one by one. If
> fail to populate for a certain mem section, print warning and its
> ->section_mem_map will be cleared to cancel the marking of being present.
> Like this, the number of mem sections marked as present could become
> less during sparse_init() execution.
> 
> Here just defer the ms->section_mem_map clearing if failed to populate
> its page tables until the last for_each_present_section_nr() loop. This
> is in preparation for later optimizing the mem map allocation.
> 
> Signed-off-by: Baoquan He <bhe@...hat.com>

Acked-By: Dave Hansen <dave.hansen@...el.com>