From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 06079FD065B for ; Wed, 11 Mar 2026 08:29:06 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4fW3nF1grdz3f1X; Wed, 11 Mar 2026 19:29:05 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2600:3c0a:e001:78e:0:1991:8:25" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1773217745; cv=none; b=Ij4za85/O8pxQMVmBEQzwgt1efE3SvRV/FNAtVbE7iANJZx8Jd7ygoYx7+5RPtf24wqOMRpPUHoV0fHbiOPPgYAOMLz93H/+bwjsNHog5IHjLN58CfxjyRb0UDgCDTZMsO3HuDyXTdC1lRj1PC6MBCQ7mMv7ylHlBygTl+tc1fgG337vu/t+TTF3CpTgAy5dq6U50tjtDK2vHuahzhXALW/XP2GTWrNtiD1qwi/S3sdPornMpUDx/Fwn8ja6U4qx03pzE/Tm+jgmWbeE1UNLNgQCRQEt3VxSBh3kQ+uzd0qjcavpctKlzdiGMVCn8Znn/ocWpBff92ZUOIPPcyUA4g== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1773217745; c=relaxed/relaxed; bh=iTqYii1hI2e00krqbtsX9LEsDy2UgfEWXTijiExHbW0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fpxE2K5xeQ3o89Id4tP6wQLpM5nQLaTmdBVrdV+LXP5bwqe58r0QymjGhsimEfJHKvfeRX/C1orRVwz9JsFFPnMt+VbnJ2jphifAXEmvcPWQemiE5C7WhS3CPzXyNAkaZdvKbok0JDSEWwT3wLVc6f9fDnFsiCXLcst5Q50UpfYpVUglYH5xZFnMrrlOiJgQYF4NVrQe1009T86H27tcq/G0VSVLPHHqCwd2IZ2RxTPdjgw9wntet6iU9XSjKSvSFIEzVp6Ogj43hfYV4zTxWC6qqQq/kt0D82dMZEtwJ/VokTVDh0+E0Ux5fpcx5fVBOtJLqHKWfb6szJYYym4c9w== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=utVavD96; dkim-atps=neutral; spf=pass (client-ip=2600:3c0a:e001:78e:0:1991:8:25; helo=sea.source.kernel.org; envelope-from=david@kernel.org; receiver=lists.ozlabs.org) smtp.mailfrom=kernel.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=utVavD96; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2600:3c0a:e001:78e:0:1991:8:25; helo=sea.source.kernel.org; envelope-from=david@kernel.org; receiver=lists.ozlabs.org) Received: from sea.source.kernel.org (sea.source.kernel.org [IPv6:2600:3c0a:e001:78e:0:1991:8:25]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4fW3nD36l2z3f1K for ; Wed, 11 Mar 2026 19:29:04 +1100 (AEDT) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id A3FF143FE5; Wed, 11 Mar 2026 08:29:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C4C3C4CEF7; Wed, 11 Mar 2026 08:28:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773217742; bh=GE6B9Axf2iqOgQ6Zt2ej9Oufrn3oudVjXjL2vTIfmAQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=utVavD961L/MIxHcghlNRfP+qmyZvTz3tZkkai8biCLxovJiwSfi721dAan4WAerP qQU5S4O+so1CV/l13lXL1pBvxe6Xcb8kk+l/bBNkxM6Og8LAf+De6dljLV/bYd9vPF RnkVuR2LJMC1aO8Mmf8ZYzGG89DCjYYyg3JerSgXRXHIS9MEy5aP+0VPOJEnsfhJP/ cAHnLbI4JCoH8Po1okfUE05z/3RGXHVkg9UE9OHdr7DaaCoUol+/nBwm0m7BwYmG4l DzBEoPXPx1/wX7BQYXu4AinRZizyRYhr3BiDVj3GhukhaNvYNRYVgru+HF9UqoHZIa O0mPmtOaDieiw== Message-ID: <5e5e0169-5197-4626-b91b-af4c13520805@kernel.org> Date: Wed, 11 Mar 2026 09:28:47 +0100 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 09/16] mm/memory: convert details->even_cows into details->skip_cows To: "Lorenzo Stoakes (Oracle)" Cc: linux-kernel@vger.kernel.org, "linux-mm @ kvack . org" , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , David Rientjes , Shakeel Butt , "Matthew Wilcox (Oracle)" , Alice Ryhl , Madhavan Srinivasan , Michael Ellerman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Jarkko Sakkinen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Greg Kroah-Hartman , =?UTF-8?Q?Arve_Hj=C3=B8nnev=C3=A5g?= , Todd Kjos , Christian Brauner , Carlos Llamas , Ian Abbott , H Hartley Sweeten , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Jason Gunthorpe , Leon Romanovsky , Dimitri Sivanich , Arnd Bergmann , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Andy Lutomirski , Vincenzo Frascino , Eric Dumazet , Neal Cardwell , "David S. Miller" , David Ahern , Jakub Kicinski , Paolo Abeni , Miguel Ojeda , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-sgx@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, rust-for-linux@vger.kernel.org, x86@kernel.org References: <20260227200848.114019-1-david@kernel.org> <20260227200848.114019-10-david@kernel.org> <091ce280-9204-4b85-bf39-5e2a61e3d0ba@lucifer.local> 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: <091ce280-9204-4b85-bf39-5e2a61e3d0ba@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit >> >> zap_page_range_single_batched( >> diff --git a/mm/memory.c b/mm/memory.c >> index fdcd2abf29c2..7d7c24c6917c 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -1554,11 +1554,13 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) >> static inline bool should_zap_cows(struct zap_details *details) > > Not sure if you fix up later, but we should probably change this function to > should_skip_cows() to keep everything consistent, otherwise this is a bit weird > and confusing. should_skip_cows() is a bit misleading on its own IMHO, as we skip the "zap" context. Would have to be something like "should_skip_cows_when_zapping()", and I am not sure if that's really worth it. So I think we can leave it as is. Thanks! > >> { >> /* By default, zap all pages */ >> - if (!details || details->reclaim_pt) >> + if (!details) >> return true; >> >> + VM_WARN_ON_ONCE(details->skip_cows && details->reclaim_pt); >> + >> /* Or, we zap COWed pages only if the caller wants to */ >> - return details->even_cows; >> + return !details->skip_cows; >> } >> >> /* Decides whether we should zap this folio with the folio pointer specified */ >> @@ -2149,8 +2151,6 @@ void unmap_vmas(struct mmu_gather *tlb, struct unmap_desc *unmap) >> struct mmu_notifier_range range; >> struct zap_details details = { >> .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP, >> - /* Careful - we need to zap private pages too! */ >> - .even_cows = true, >> }; >> >> vma = unmap->first; >> @@ -4282,7 +4282,7 @@ void unmap_mapping_folio(struct folio *folio) >> first_index = folio->index; >> last_index = folio_next_index(folio) - 1; >> >> - details.even_cows = false; >> + details.skip_cows = true; >> details.single_folio = folio; >> details.zap_flags = ZAP_FLAG_DROP_MARKER; >> >> @@ -4312,7 +4312,7 @@ void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, >> pgoff_t first_index = start; >> pgoff_t last_index = start + nr - 1; >> >> - details.even_cows = even_cows; >> + details.skip_cows = !even_cows; > > Not sure if you clean up later, but seems sensible to cascade the change into > the local boolean here. There are too many unmap_mapping_range() users for me to want to change the external interface :) What I was thinking is that probably there should be two independent user-facing functions, instead of having this magical bool passed around Because I am sure, most users don't really know whether to set it to true or false ... But that's something for another cleanup. (I left the whole unmap_mapping_pages() interface etc alone in this series) -- Cheers, David