linux-kernel - Re: [PATCH v10 11/12] mm/vmalloc: Hugepage vmalloc mappings

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Date:   Sun, 24 Jan 2021 10:06:09 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Christoph Hellwig <hch@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Zefan Li <lizefan@...wei.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Ding Tianhong <dingtianhong@...wei.com>
Subject: Re: [PATCH v10 11/12] mm/vmalloc: Hugepage vmalloc mappings

On 1/24/21 7:07 AM, Christoph Hellwig wrote:
>> +config HAVE_ARCH_HUGE_VMALLOC
>> +	depends on HAVE_ARCH_HUGE_VMAP
>> +	bool
>> +	help
>> +	  Archs that select this would be capable of PMD-sized vmaps (i.e.,
>> +	  arch_vmap_pmd_supported() returns true), and they must make no
>> +	  assumptions that vmalloc memory is mapped with PAGE_SIZE ptes. The
>> +	  VM_NOHUGE flag can be used to prohibit arch-specific allocations from
>> +	  using hugepages to help with this (e.g., modules may require it).
> help texts don't make sense for options that aren't user visible.

It's good that the Kconfig symbol is documented and it's better here
than having to dig thru git commit logs IMO.

It could be done as "# Arhcs that select" style comments instead
of Kconfig help text.


-- 
~Randy