From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 331992D0C63; Wed, 16 Sep 2026 14:48:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789570090; cv=none; b=J+1aVUZOhJFgQ4X+LHYhwrPhf/VTQhKXJ4q3QcX67IyfQASpRn6kq6t1bIDN1Z7iLR8SwFOdRCsW3Og7artHPAN/+4YoH+z1jB3qtbGl5IDRRibUXpET1l3O9ZWkgLehTUYOXfCCDGJxFI5Huybv7X74jkPDyp05aTk2/cC91VU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789570090; c=relaxed/simple; bh=0uv1KDeyuJxKLht0Tyg4kFYOmiLKgCN6hnIBqP2X7nQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WywCENAK63APUa/oyahUUnJz/YVUpc99WCoP/wRYH5amaDn8U0yAXOclHjym1yK8TCk6iG2YCuk+z46MFCWugFV2bxkcNXnOMM8AH9Qx8oPXIsAyptVIfm2xggtslVTE6n8gotx1E0r2IDRSbDyicAe0AM2A7bPHdgTJY+SCANU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=T7dUka4q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="T7dUka4q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6A2F1F000FF; Wed, 16 Sep 2026 14:48:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789570089; bh=nRqwql2BGBgUg07i+72w0ggBRElWDeq7lDyHdnUO4T8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=T7dUka4qR1knSUCYclelAUpkpvYpsoovJAQnKd5Tw2PiCwpjbdXXUiGYAiUD9MZ+5 8xsaCKEZI+MF8oooxybgsGVjvLgqKgfMJ8TDdCEYRmGqPkvZPMlSfDSi+JJ14rIK1B SDrnoeLUUlOjUMm4xGH4+pjVphbUnO7PY05aw7M7z3bVK32w7JcSRP/CbVyhFRVA9Y lrZtKz5uodD2fpfrnd7cDJ6vsB4QaZQ/9Nt3UayY+v9s5sdRqvI+bPBp3RKK4O69Kj eAPjuEOaQB0XxyxBZO2BTcOsBn/0X0u6HbVBgeRCzC4Nn6kzNsfzF8n2ZPlZKI55v8 fSwn5i38fYsJw== Message-ID: <5437871c-d9ee-49d2-b24f-965c73c29c3e@kernel.org> Date: Wed, 16 Sep 2026 16:48:04 +0200 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] mm/madvise: reclaim isolated folios if PTE restart fails To: Gregory Price , "Lorenzo Stoakes (ARM)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, liam@infradead.org, vbabka@kernel.org, jannh@google.com, wangjiexun@tinylab.org, sashiko-bot , stable@vger.kernel.org References: <20260912110832.3203902-1-gourry@gourry.net> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/16/26 16:42, Gregory Price wrote: > On Wed, Sep 16, 2026 at 03:12:53PM +0100, Lorenzo Stoakes (ARM) wrote: >>> >>> Going to spend a little more time testing and tweaking before I post it. >>> >>> I've been working on a making more extensive unit tests for certain >>> parts of mm/ and this might be a good time to look at whether I can >>> introduce a piece of it. >> >> Nice, curious as to how? >> >> Have you tried the userland VMA tests btw? Not tooting my own horn so to >> speak :P but it's nice, though it comes at a bit of a cost in how the files >> have to be set up... >> > > Yes, in fact I used that as a start for exploring how I might make other > components testable the same way. > > "Stubs... stubs everywhere" > > There's basically 4 testing mechanisms i explored: > > 1) selftest > 2) Usermode Linux (UML) > 3) Userland stuff like VMA > 4) Linux Test Project (for syscall and ABI testing) > > selftests are really limited and actually create a maintenance burden, > they're not real unit tests and are highly dependent on the actual > machine configuration which is super annoying. > > But, lets take the page allocator as an example. > > The only piece of the page allocator that "should" (cough, simplifying > here a bit) be machine specific is zone and node configurations... but > I'm not convinced that this should require a full VM to unit-test. I told Brendan exactly that (try stubbing it) and he tried ... and had to give up at some point because it just wasn't feasible. ;) -- Cheers, David