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Date: Sat, 14 Mar 2026 15:27:51 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@kernel.org>, Lorenzo Stoakes
 <lorenzo.stoakes@oracle.com>, Hugh Dickins <hughd@google.com>, Baolin Wang
 <baolin.wang@linux.alibaba.com>, "Liam R. Howlett"
 <Liam.Howlett@oracle.com>, Nico Pache <npache@redhat.com>, Ryan Roberts
 <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>, Barry Song
 <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>, Matthew Wilcox
 <willy@infradead.org>, Bas van Dijk <bas@dfinity.org>, Eero Kelly
 <eero.kelly@dfinity.org>, Andrew Battat <andrew.battat@dfinity.org>, Adam
 Bratschi-Kaye <adam.bratschikaye@dfinity.org>, linux-mm@kvack.org,
 linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] selftests/mm: add folio_split() and filemap_get_entry()
 race test
Message-Id: <20260314152751.101b5d04d3753f75027b9cd6@linux-foundation.org>
In-Reply-To: <20260313114037.3593642-1-ziy@nvidia.com>
References: <20260313114037.3593642-1-ziy@nvidia.com>
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On Fri, 13 Mar 2026 07:40:37 -0400 Zi Yan <ziy@nvidia.com> wrote:

> The added folio_split_race_test is a modified C port of the race condition
> test from [1]. The test creates shmem huge pages shared by both a parent
> and a child processes, where the parent process punches holes in the shmem
> to cause folio_split() in the kernel and the child process reads the shmem
> in 16 threads to cause filemap_get_entry() in the kernel.
> filemap_get_entry() reads the folio and xarray split by folio_split()
> locklessly. The original test[2] is written in rust and uses memfd (shmem
> backed). This C port uses shmem directly.

Cool.

> Note: the initial rust to C conversion is done by Cursor.

Hence the CaMeLcAsE "struct SharedCtl".  Fair enough.

> Link: https://lore.kernel.org/all/CAKNNEtw5_kZomhkugedKMPOG-sxs5Q5OLumWJdiWXv+C9Yct0w@mail.gmail.com/ [1]
> Link: https://github.com/dfinity/thp-madv-remove-test [2]

I couldn't immediately find any licensing info there.  Bas and Adam,
please advise?  And sending your Signed-off-by's would be appropriate.

Thanks.