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

From: Lorenzo Stoakes <lstoakes@gmail.com>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-mm@kvack.org, Shuah Khan <shuah@kernel.org>,
	Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kirill A Shutemov <kirill@shutemov.name>,
	"Liam R. Howlett" <liam.howlett@oracle.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Kalesh Singh <kaleshsingh@google.com>,
	Lokesh Gidra <lokeshgidra@google.com>
Subject: Re: [PATCH v5 6/7] selftests: mm: Add a test for remapping within a range
Date: Sun, 27 Aug 2023 11:15:20 +0100	[thread overview]
Message-ID: <fb429d82-4576-42d7-b51f-7a72f7f8caec@lucifer.local> (raw)
In-Reply-To: <08ce8c61-e7a2-417a-a3cc-d20861753ae8@lucifer.local>

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]