linux-kernel - Re: [RFC 1/3] mm: change vma_is_anonymous to vma_is_private

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Date:   Thu, 21 Apr 2022 20:28:32 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Nico Pache <npache@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Yang Shi <shy828301@...il.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        William Kucharski <william.kucharski@...cle.com>,
        Hugh Dickins <hughd@...gle.com>
Subject: Re: [RFC 1/3] mm: change vma_is_anonymous to vma_is_private_anon

On Thu, Apr 21, 2022 at 03:05:31PM -0400, Nico Pache wrote:
> The vma_is_anonymous function isn't fully indicative of what it checks.
> 
> Without having full knowledge of the mmap process, one may incorrectly
> assume this covers all types of anonymous memory; which is not the case.

Is your complaint that anonymous memory can also be found in file VMAs
that were mapped with MAP_PRIVATE?  ie COWed pages?

I don't think renaming this function is appropriate.  It's whether
the VMA is anonymous, not whether the VMA can contain anonymous
pages.