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Subject: Re: [PATCH v2 3/3] mm/vmalloc: fix vmalloc_to_page for huge vmap
 mappings
To: Nicholas Piggin <npiggin@gmail.com>,
 "linux-mm @ kvack . org" <linux-mm@kvack.org>
References: <20190701064026.970-1-npiggin@gmail.com>
 <20190701064026.970-4-npiggin@gmail.com>
From: Anshuman Khandual <anshuman.khandual@arm.com>
Message-ID: <8369ca48-ebab-fe2d-363d-00769827fd0b@arm.com>
Date: Mon, 1 Jul 2019 15:28:51 +0530
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Cc: Mark Rutland <mark.rutland@arm.com>,
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On 07/01/2019 12:10 PM, Nicholas Piggin wrote:
> vmalloc_to_page returns NULL for addresses mapped by larger pages[*].
> Whether or not a vmap is huge depends on the architecture details,
> alignments, boot options, etc., which the caller can not be expected
> to know. Therefore HUGE_VMAP is a regression for vmalloc_to_page.
> 
> This change teaches vmalloc_to_page about larger pages, and returns
> the struct page that corresponds to the offset within the large page.
> This makes the API agnostic to mapping implementation details.
> 
> [*] As explained by commit 029c54b095995 ("mm/vmalloc.c: huge-vmap:
>     fail gracefully on unexpected huge vmap mappings")
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>