linux-kernel - Re: [PATCH v5 6/7] selftests: mm: Add a test for remapping within a range

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Message-ID: <fb429d82-4576-42d7-b51f-7a72f7f8caec@lucifer.local>
Date:   Sun, 27 Aug 2023 11:15:20 +0100
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-mm@...ck.org, Shuah Khan <shuah@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kirill A Shutemov <kirill@...temov.name>,
        "Liam R. Howlett" <liam.howlett@...cle.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Kalesh Singh <kaleshsingh@...gle.com>,
        Lokesh Gidra <lokeshgidra@...gle.com>
Subject: Re: [PATCH v5 6/7] selftests: mm: Add a test for remapping within a
 range

On Sun, Aug 27, 2023 at 10:57:59AM +0100, Lorenzo Stoakes wrote:
[snip]

> > +/*
> > + * Verify that an mremap within a range does not cause corruption
> > + * of unrelated part of range.
> > + *
> > + * Consider the following range which is 2MB aligned and is
> > + * a part of a larger 10MB range which is not shown. Each
> > + * character is 256KB below making the source and destination

Just noticed, I think you misspeak here, as this test doens't seem to
offset by 256 KiB? That is the strategy for mremap_move_1mb_from_start()
rather than this test so perhaps comment needs to be moved around?

 * 2MB each. The lower case letters are moved (s to d) and the
 * upper case letters are not moved. The below test verifies
 * that the upper case S letters are not corrupted by the
 * adjacent mremap.
 *
 * |DDDDddddSSSSssss|
 */
 static void mremap_move_within_range(char pattern_seed)

[snip]