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Subject: Re: [PATCH] mm: add VM_STATIC flag to vmalloc and prevent from removing the areas
From: Hoeun Ryu <hoeun.ryu@gmail.com>
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Date: Wed, 12 Apr 2017 20:42:08 +0900
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Andreas Dilger <adilger@dilger.ca>, Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@suse.com>,
        Chris Wilson <chris@chris-wilson.co.uk>,
        Ingo Molnar <mingo@kernel.org>, zijun_hu <zijun_hu@htc.com>,
        Matthew Wilcox <mawilcox@microsoft.com>,
        Thomas Garnier <thgarnie@google.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        linux-arch@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
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To: Christoph Hellwig <hch@infradead.org>
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> On Apr 12, 2017, at 3:02 PM, Christoph Hellwig <hch@infradead.org> wrote:
> 
>> On Wed, Apr 12, 2017 at 02:01:59PM +0900, Hoeun Ryu wrote:
>> vm_area_add_early/vm_area_register_early() are used to reserve vmalloc area
>> during boot process and those virtually mapped areas are never unmapped.
>> So `OR` VM_STATIC flag to the areas in vmalloc_init() when importing
>> existing vmlist entries and prevent those areas from being removed from the
>> rbtree by accident.
> 
> How would they be removed "by accident"?

I don't mean actual use-cases, but I just want to make it robust against like programming errors.