linux-kernel - Re: [PATCH v8 22/23] mm: Enable PTE markers by default

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Message-ID: <Yl8YE+w+OWz5RNOL@cmpxchg.org>
Date:   Tue, 19 Apr 2022 16:14:11 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Jerome Glisse <jglisse@...hat.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Alistair Popple <apopple@...dia.com>
Subject: Re: [PATCH v8 22/23] mm: Enable PTE markers by default

Hi Peter,

On Tue, Apr 19, 2022 at 03:59:21PM -0400, Peter Xu wrote:
> @@ -910,16 +910,16 @@ config ANON_VMA_NAME
>  	  difference in their name.
>  
>  config PTE_MARKER
> -	bool "Marker PTEs support"
> -	default y
> +	bool
>  
>  	help
>  	  Allows to create marker PTEs for file-backed memory.
>
>  config PTE_MARKER_UFFD_WP
> -	bool "Marker PTEs support for userfaultfd write protection"
> +	bool "Userfaultfd write protection support for shmem/hugetlbfs"
>  	default y
> -	depends on PTE_MARKER && HAVE_ARCH_USERFAULTFD_WP
> +	depends on HAVE_ARCH_USERFAULTFD_WP
> +	select PTE_MARKER

This is much easier to understand, thanks!

Btw, this doesn't do much without userfaultfd being enabled in
general, right? Would it make sense to have it next to 'config
USERFAULTFD' as a sub-option?