From: Sarthak Sharma <sarthak.sharma@arm.com>
To: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>,
"Liam R . Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Shuah Khan <shuah@kernel.org>,
John Hubbard <jhubbard@nvidia.com>,
Kalesh Singh <kaleshsingh@google.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Park Tae-sun <ts930@dgu.ac.kr>,
linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND 0/9] selftests/mm: improve mremap_test
Date: Tue, 29 Sep 2026 11:24:28 +0530 [thread overview]
Message-ID: <b8da4a73-296b-47f9-95dd-b8a74f3a0984@arm.com> (raw)
In-Reply-To: <20260924050009.19974-1-sarthak.sharma@arm.com>
On 9/24/26 10:30 AM, Sarthak Sharma wrote:
> This series fixes several correctness issues in mremap_test and
> simplifies and strengthens its data validation.
>
> Patch 1 converts the mremap_test to use kselftest helpers, removes
> manual tracking of failed tests and corrects some spelling errors.
>
> Patches 2 to 5 fix userfaultfd skipping, unexpected mremap success
> handling, multi-VMA data validation and failure reporting when data
> corruption is detected.
>
> Patch 6 removes the randomization and uses a simple pattern based approach.
>
> Patch 7 removes perf tests and timing infrastructure.
>
> Patch 8 removes validation threshold and always validates complete mappings.
>
> Patch 9 strengthens the multi VMA validation by also checking the
> mapping state of holes after remapping.
Hello everyone! Just wanted to check if someone has had a chance to look
at the series.
Also, Sashiko has a concern [1], and I had the same while posting the
series. I hope I can get some opinion from the community.
Currently, for PUD remap tests, we allocate a source mapping of 2GB. We
only fault in the first threshold_mb amount of memory, remap the whole
region, and validate the already faulted threshold_mb amount of memory,
which is, by default, equal to 4MB and can be changed by the user by
supplying a command line option.
Since we plan to remove all command line options from teh selftests, I
removed threshold_mb altogether, following some discussion on the list
[2]. This would now cause a 2GB source mapping, and its contents copied
from another 2GB buffer. This causes the process to have a 4GB RSS.
Sashiko says that this can cause OOM killing in small CI machines.
Would it be okay to keep a 4GB RSS in this case, or should we find some
other way of validating a part of the whole range instead?
[1]
https://sashiko.dev/#/patchset/20260924050009.19974-1-sarthak.sharma%40arm.com
[2]
https://lore.kernel.org/all/2e34b619-085f-4a9c-bb41-bc024fd40dd7@kernel.org/
next prev parent reply other threads:[~2026-09-29 5:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 5:00 Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 1/9] selftests/mm: mremap_test: use kselftest helpers Sarthak Sharma
2026-09-29 7:58 ` David Hildenbrand (Arm)
2026-09-29 9:12 ` Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 2/9] selftests/mm: mremap_test: skip test when userfaultfd is unavailable Sarthak Sharma
2026-09-29 8:00 ` David Hildenbrand (Arm)
2026-09-29 9:17 ` Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 3/9] selftests/mm: mremap_test: fail unexpected mremap successes Sarthak Sharma
2026-09-29 8:17 ` David Hildenbrand (Arm)
2026-09-24 5:00 ` [PATCH RESEND 4/9] selftests/mm: mremap_test: correct multiple VMA range size Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 5/9] selftests/mm: mremap_test: fail on data corruption Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 6/9] selftests/mm: mremap_test: replace random data with deterministic pattern Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 7/9] selftests/mm: mremap_test: remove perf tests and timing Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 8/9] selftests/mm: mremap_test: remove validation threshold Sarthak Sharma
2026-09-24 5:00 ` [PATCH RESEND 9/9] selftests/mm: mremap_test: strengthen multi VMA validation Sarthak Sharma
2026-09-29 5:54 ` Sarthak Sharma [this message]
2026-09-29 7:32 ` [PATCH RESEND 0/9] selftests/mm: improve mremap_test Kalesh Singh
2026-09-29 7:47 ` David Hildenbrand (Arm)
2026-09-29 9:05 ` Sarthak Sharma
2026-09-29 8:36 ` Lorenzo Stoakes (ARM)
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