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Subject: Re: [PATCH 1/3] mm: add apply_to_existing_pages helper
To:     Daniel Axtens <dja@axtens.net>, kasan-dev@googlegroups.com,
        linux-mm@kvack.org, glider@google.com,
        linux-kernel@vger.kernel.org, dvyukov@google.com
Cc:     daniel@iogearbox.net, cai@lca.pw,
        Andrew Morton <akpm@linux-foundation.org>
References: <20191205140407.1874-1-dja@axtens.net>
From:   Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <c4694ce0-2166-325c-bdca-1655c7c359f9@virtuozzo.com>
Date:   Fri, 6 Dec 2019 19:24:25 +0300
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On 12/5/19 5:04 PM, Daniel Axtens wrote:
> apply_to_page_range takes an address range, and if any parts of it
> are not covered by the existing page table hierarchy, it allocates
> memory to fill them in.
> 
> In some use cases, this is not what we want - we want to be able to
> operate exclusively on PTEs that are already in the tables.
> 
> Add apply_to_existing_pages for this. Adjust the walker functions
> for apply_to_page_range to take 'create', which switches them between
> the old and new modes.
> 
> This will be used in KASAN vmalloc.
> 
> Signed-off-by: Daniel Axtens <dja@axtens.net>

Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>