From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1D9E93B9DA1; Wed, 29 Apr 2026 09:09:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777453799; cv=none; b=O8Mq/rcCMaTBzqPFP8etAMb42ElWbjbI9v5JpoMAmB0M6qxoFmDlC6Q6SUivYa+pLVIUMMRXP0U5jiXBUD8+8KeIajYI56xMCHj0YbTi2IIpjju3TZzkNqWlM0d85cFZ3RzrbDOlbg0wQE44v1UvUs+Zj1hwRziQHyTy3emVigo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777453799; c=relaxed/simple; bh=U+qtUGkVcFIOlc8S8UBttfIQrvSv8Unx0HYdPMMzu/s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FnBzIFw3iUcNnDSw8cZMzS4sueROAhZC1hT+QetZA37ITmMEsMAQ0LPRc6jGuC3UO0q6ld0ivyvPoMwUyxrhSyjYqe3NhOP9UI03ie7MYk3wGn2ihGpFEa41GkO5d/gqL81NHQqa5+U4sOm1rD7x8po8n9HnxVUs1LYgWNw3D3k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Z+MvByLP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Z+MvByLP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7CA9C19425; Wed, 29 Apr 2026 09:09:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777453798; bh=U+qtUGkVcFIOlc8S8UBttfIQrvSv8Unx0HYdPMMzu/s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Z+MvByLPCyLX3thXV7RgPBjsjmxkuAXCIy4GXER9SykX7CHrlgSjjUZyquB4KqDcp jE6yx5hmr/1rBMFnHAQeb4njCzfxnDS9Co6U2mZwBoMBNYEkTNvqPRNWu+Qd+DIyyr HWM4uamBtdonUqzUYZM5AzY8WIBP3Q6Gfu2ml4ehQ4kOOLyQgQeMAwj23hqJX5T/hE E2ZZlTeKtyQ10nWnUmrbLFCRU15KsZQIGtahN+iRUNNOFYYOepadE5UHGhl5Dd0Jow 3SJ9urBDneMgL5mF0Cw1Z+3nieDQZ3O47aX5O/vbcVAbyuPItDIlozZqV+nz4/CdJG RXiuFE/4QctTg== Message-ID: <7f98f461-62a7-455d-a7a8-cb8928465946@kernel.org> Date: Wed, 29 Apr 2026 11:09:55 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/3] mm: process_mrelease: skip LRU movement for exclusive file folios To: Michal Hocko , Minchan Kim Cc: Suren Baghdasaryan , akpm@linux-foundation.org, hca@linux.ibm.com, linux-s390@vger.kernel.org, brauner@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, timmurray@google.com, "Liam R. Howlett" References: <20260421230239.172582-3-minchan@kernel.org> <7c7da8ae-cd39-4edf-b94f-c79ab85df456@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/29/26 10:18, Michal Hocko wrote: > On Tue 28-04-26 18:19:31, Minchan Kim wrote: >> On Tue, Apr 28, 2026 at 08:56:36AM +0200, Michal Hocko wrote: > [...] >>> DESCRIPTION >>> The process_mrelease() system call is used to free the memory of >>> an exiting process. >> >> "Free the memory of an exiting process" implies all memory, not just >> anonymous. User cannot know it will free only anonymous, and I am trying to >> make it work as intended by completing a symmetric reclamation path. > > Page cache doesn't belong to any process. > > [...] > >> >From cf292f8f8ead8df9161aad342c36633ffa90257f Mon Sep 17 00:00:00 2001 >> From: Minchan Kim >> Date: Tue, 28 Apr 2026 16:39:06 -0700 >> Subject: [PATCH] mm: process_mrelease: skip LRU movement and expedite clean >> file folio reclaim > > I will let others to discuss this. I maintain my position that this is a > hack for a very particular use case and you still seem to not explain > non-Android users of the syscall. Anyway, I will not repeat myself here. > One thing that got lost in the thread here: this code path is not process_mrelease specific? We seem to end up in __oom_reap_task_mm() also from ordinary oom_reap_task_mm(). There, we unconditionally set MMF_UNSTABLE to then zap_vma_for_reaping() where memory can be "reaped". So why is there "process_mrelease" part of the patch subject at all? The only other scenario where we set MMF_UNSTABLE seems to be when we run into trouble during fork(). CCing Liam, I wonder what it would take to remove MMF_UNSTABLE from fork code now that we handle some memory freeing while aborting fork() "more elegantly". Unrelated stupid question: would things be clearer if we could rename MMF_UNSTABLE to MMF_OOM_REAPING once figure out whether aborting fork() still really needs it? Back to Michal's original question: I guess the real question is the interaction with memory reclaim that would just collect the access bits beforehand. -- Cheers, David