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 7EA3F4FFA3B for ; Mon, 19 Oct 2026 14:21:17 +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=1792419678; cv=none; b=SCNuCWzKCmfbTohCLQe/G/SpPaAq9qMKG3MW+54A6wA++gvAlpJJ6ihaqUrlKxMhNGqqZQSqmTGGsQPvBQpVVuuFAFAX/QvMNsJRfW+ZeLK9TXG+sOtSf+cIYXZNCkBvRqbqWE2oxWPPGis5Tg97GXLsLy8arPxbP9mbynW8YR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792419678; c=relaxed/simple; bh=QFXmO748stJzV4KT4lqquqiQ6JsrCD+yULx5fwpQifs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=C+5B8VOqHg68XOTeUIOeBYx7vkRzrHsMf74OONKtdbEj28IweDmkkNG62yRCESp8kD0CHmd/4wzQYdGfR8/eDhcT0lLgXc0Wa8dbsUWM4eJB3EdnpLUnoAbmO8ikj8GiKFNyGJQ0YqOrHss3WBxqtY9PXBhpqjVX8iKQb61GmM8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KWhNYPOa; 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="KWhNYPOa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 165381F000C4; Mon, 19 Oct 2026 14:21:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792419677; bh=J5wpE0Ce426czQX30iKC6nqUoHP2omOb5e7+spqpF9Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=KWhNYPOan5xPFiCT6IwXfvfrXkuVjX/oWCqOUSeICiPwrZGkX9WJjhqcjJwacxwzL fexJ2d1hVI7uZCaQ/V7pm9RZfn50zIa9bpuRQfLOQHRkFDI4J+IOQA1EK49VtYfvLF t/b5cXp9Rc5ZsEmjlPclmNKjtMk4p0pEm6PQN/DGostcKs+ZoYHFqlGFGGlXTqgxiv btrwUTIPYYqaHUQuGN1m85efSCk0MZL53djPsgeoKt7erFk0fHFvMJrwmAggkh2mF8 rQv31lIwCs4WfpEYwUu4A8u/X7vPTc80Kzq3oK9niFH2dCbtEwkuc9VeoK+ROSw4l3 2eQUGxgZv5aAw== Message-ID: <046e3eef-aae6-4361-821e-06cadf250d49@kernel.org> Date: Mon, 19 Oct 2026 16:21:09 +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 RFC v2] mm: introduce copy_mc_highpages() and batch copy in folio_mc_copy() To: "Garg, Shivank" , "pfalcato@suse.de" Cc: "tejavojjala@google.com" , "Rao, Bharata Bhasker" , "rppt@kernel.org" , "david.laight.linux@gmail.com" , "ankur.a.arora@oracle.com" , "dave.hansen@linux.intel.com" , "vbabka@kernel.org" , "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "surenb@google.com" , "linux-mm@kvack.org" , "nhuhuan@google.com" , "Salunke, Hrushikesh" , "tglx@kernel.org" , "liam@infradead.org" , "hpa@zytor.com" , "mhocko@suse.com" , "bp@alien8.de" , "ljs@kernel.org" , "rientjes@google.com" , "torvalds@linuxfoundation.org" , "x86@kernel.org" References: <20261019-batpagecopy-v2-1-d75e7d0dfaae@amd.com> <0346e29faa551efb6a4e21a920d344f5f9b918e5.camel@amd.com> 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 10/19/26 15:10, Garg, Shivank wrote: > On Mon, 2026-10-19 at 14:23 +0200, David Hildenbrand (Arm) wrote: >>> >>> I would suggest that perhaps this should be the fallback for non-preemptible >>> models. But it gets a little weird with PREEMPT_DYNAMIC I think? >> >> Why can't we just use PROCESS_PAGES_NON_PREEMPT_BATCH where we have similar >> handling already? >> >>> > > I did not reuse PROCESS_PAGES_NON_PREEMPT_BATCH because it depends on > whether clear_pages is defined. While COPY_MC_PAGES_NON_PREEMPT_BATCH > depends on copy_mc_to_kernel and other constraints. So, using a single > param for both would make it more messy. If it would stay it would all have to be cleaned up to end up with a single one. > > However as Pedro pointed, most architectures are full preempt/preempt lazy, > and with this commit 7dadeaa6e851 ("sched: Further restrict the > preemption modes"), for PREEMPT_DYNAMIC, preempt=none and preempt=voluntary > are rejected at boot. preempt_model_preemptible() is therefore always > true for this case. > > So, this can be simplfied to drop the COPY_MC_PAGES_NON_PREEMPT_BATCH. Can we simplify the zeroing part as well? -- Cheers, David