From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0EF833F12EF; Tue, 29 Sep 2026 05:54:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790661278; cv=none; b=Oi/RqXCLxC9GllbbtiIWMy3SiuhDZ+RobuqQBOI/ONckVTwaYJ9z/c51Go0Z2P+jCs+vZ7JLMxogPXHayA7aTo+AnfhxS0ShMZwWREgH0BzO0J8DiebpLDfKDHf4yZ8TTStWQU/aHtvEtrcYnJ/+/2CcgLJCJHueiwY6Ygg62t8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790661278; c=relaxed/simple; bh=8nkwXY0A5RFYOmpZpCVpTJMUESTE+g43aAvec0iYxIA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WeiMTGpdYJrCXULfFcXLqXOP4o5/l8sPRF3JzY+A3mWQxFgweZk+TS5ruSz80mcnvKyCzZkrkhmYCtSj9LcF6RN7G7eNjlgqVZobE2d0h1weu6y2v21RaYn/Zw8NCDWTL7ZkTHfUYU/kZ+WUsX8UUqKkco5npVj8p29jyFxcmm8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=r+09+Qtn; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="r+09+Qtn" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6BC8E1684; Mon, 28 Sep 2026 22:54:31 -0700 (PDT) Received: from [10.164.19.84] (a081061.arm.com [10.164.19.84]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B643C3F85F; Mon, 28 Sep 2026 22:54:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790661274; bh=8nkwXY0A5RFYOmpZpCVpTJMUESTE+g43aAvec0iYxIA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=r+09+QtnSFt+dnSfRuQGaaldiXc4mhTOPri6hVSHqcL9koINFR2ZnAgeqwsSkGa6C 2jPyj+B6rBWhOoUuyCIeZnxqz3AJlFX3dC5DeZAGcgotS5umquFypWyjnXgnuLFlCP vxY8dFVP25lHN7cuNL79b6G/tNeBObrPUpdUQAeI= Message-ID: Date: Tue, 29 Sep 2026 11:24:28 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RESEND 0/9] selftests/mm: improve mremap_test To: Andrew Morton , David Hildenbrand Cc: Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , John Hubbard , Kalesh Singh , Anshuman Khandual , Park Tae-sun , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260924050009.19974-1-sarthak.sharma@arm.com> Content-Language: en-US From: Sarthak Sharma In-Reply-To: <20260924050009.19974-1-sarthak.sharma@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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/