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 3DA673C279B for ; Mon, 17 Aug 2026 22:12:05 +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=1787004726; cv=none; b=MUbXMBbKorrLz15ENs8ukz6cd2w5u0g8BcPa87zmIj9ZerNG7vPAHZb5ZHVjbnxougEuRaX3D2jPGsnm/x7AAHZdID+6qCzY4wFsq0eWtzCfArh2qx/uEM2vwNKP/RkqfpnnA/YZvxlAQP77/gBA/LdLVrv53rQv56EJMA2KkoE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787004726; c=relaxed/simple; bh=R70ue6Nkmpoj4wHGHwDzIgqySGri40o/0vRfXO8nLxU=; h=Date:From:To:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=b8So/PYHcGvcdiSn9oSGLUFOtjSNjEz/5n+HPN06JPF1D03/iWSQyZDcl0O4rNgAfii5pO4eQRNBIrCBr7GFON+1PewYuGFjUvs7L5wY2E0yPL+Mkz1ixu67yPqw3XqNWMsAWPytprkvKV1I4+WI8JjNMKv28X/YlxaNgnoCOIA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=hMOtHPnz; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="hMOtHPnz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 954961F000E9; Mon, 17 Aug 2026 22:12:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1787004725; bh=qDUxGBkk44tOjpfh9EXGkQkAJonIYZKKED1bmZdyP9I=; h=Date:From:To:Subject:In-Reply-To:References; b=hMOtHPnze4qedvrdjm0cpkZabhZxEXLK4VPdmuyNtKV4pc/tLykmuM5sdH94rcq4+ m3iaEQRJv/0Luv7TMWuXSMzR9ps5wi7Kq8U9wuhf+ebhR0Ubs/63mlDYYo9/Ro0CWx WOLv7oHaIMQu+v5N8oZOHkGfdvOaQRwtyowf6ctc= Date: Mon, 17 Aug 2026 15:12:04 -0700 From: Andrew Morton To: Hui Su , apopple@nvidia.com, balbirs@nvidia.com, byungchul@sk.com, david@kernel.org, gourry@gourry.net, joshua.hahnjy@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, matthew.brost@intel.com, rakie.kim@sk.com, ying.huang@linux.alibaba.com, ziy@nvidia.com Subject: Re: [PATCH] mm/migrate_device: fix cache flush when replacing huge zero PMD Message-Id: <20260817151204.50749d6a3e16e322e6f05d7d@linux-foundation.org> In-Reply-To: <20260817143415.60bedb09819d13a2dc0fbe63@linux-foundation.org> References: <20260817090640.287a9a415da49e3974797aa4@linux-foundation.org> <20260817163646.929678-1-sh_def@163.com> <20260817143415.60bedb09819d13a2dc0fbe63@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 17 Aug 2026 14:34:15 -0700 Andrew Morton wrote: > > Hi, > > > > I took a closer look at this, there is no userspace-visible effect today. > > > > The architectures that currently enable ARCH_ENABLE_THP_MIGRATION use > > no-op implementations of flush_cache_page()/flush_cache_range(). > > 32-bit ARM has non-trivial implementations, but does not enable > > ARCH_ENABLE_THP_MIGRATION. > > > > So this appears to be a latent API misuse rather than a currently > > observable bug, and I don't think a stable backport is necessary. > > OK, thanks for checking. > > > Should I resend a v2 clarifying the userspace-visible effect in the > > changelog? > > Yes please, after 7.3-rc1. Actually, I updated the changelog and added it to next week's queue-for-Linus.