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 A7BC138F629; Mon, 18 May 2026 19:53:35 +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=1779134015; cv=none; b=jtEr9wK1oeN85FrLMoOa+uwrPN5GCmGO1kv+mj1yYil/ari1+bOFwRx8ukjDL/U/7B8EIS7cexB+dHVZ3YQpP78I+hNPVBPLGjG5OUMAkLWVOtkIXmSwnrwcsR2vmGuLC16pA3p/P4HWGprE6jMsK2m/xFX/KtqThsCI8xX/U48= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779134015; c=relaxed/simple; bh=nZ0D31rkJ58LmFaS2W1jBidt3T9eg8DSZrXA9r0f9Ac=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ykw6oVVxp7n6980qeeRHQr6vvFgXU0B5NJmSUSxmVfeCbeDJ0Bn+LISrtbW2v8274RkPpLZh8fQM5YqRxnK4UDPs0PaiYBDCsM4EcH/3bAOghP6UEOhJy9gYrU6HP80peMN/2277jJqwgXHXg0ls8wfmiq7D9JwY0yFYSavZ9BY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O7U/5SfC; 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="O7U/5SfC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 245BFC2BCC6; Mon, 18 May 2026 19:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779134015; bh=nZ0D31rkJ58LmFaS2W1jBidt3T9eg8DSZrXA9r0f9Ac=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=O7U/5SfC8PP4wcXOspJBnyLZb8fjuk1HP3PEPyF0HIn2Ol0sAqvYeirvFb76FXTEV 7bP5b9jtSmSp0lbLozkGPZzV2ePN+x3oKsnbmcjC3dGCgssQwrpbZEcc4f+Yrh9Zua DriwYDD0PKgwef2oYAWjf8kFFx4pIo645Am5zxDzXKIwL0mUfQWQn+WqmrU6EUuGMC 4oHyw0BCaJQeh3JHzSX28eKEPukAnj95j2ZxM40kb+iIrvhAqcNHOH2uXrsebtcEn+ cLD/nrjnJYs4zdQz08NAjMpyWK/YGQqSjN2NP8c+cBNlGfIOS3hLZ4dA+dGnlzn/sI j6XR/xgodjqmA== Date: Mon, 18 May 2026 09:53:34 -1000 From: Tejun Heo To: "David Hildenbrand (Arm)" Cc: David Vernet , Andrea Righi , Changwoo Min , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Andrew Morton , Mike Rapoport , Emil Tsalapatis , sched-ext@lists.linux.dev, bpf@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/8] mm: Add ptep_try_install() for lockless empty-slot installs Message-ID: References: <20260517211232.1670594-1-tj@kernel.org> <20260517211232.1670594-2-tj@kernel.org> <9ba50fd2-077e-4291-9276-9adb18186873@kernel.org> 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-Disposition: inline In-Reply-To: <9ba50fd2-077e-4291-9276-9adb18186873@kernel.org> Hello, On Mon, May 18, 2026 at 10:06:29AM +0200, David Hildenbrand (Arm) wrote: > On 5/17/26 23:12, Tejun Heo wrote: > > +static inline bool ptep_try_install(pte_t *ptep, pte_t new_pte) > > +{ > > + return false; > > +} > > +#endif > > Ehm, what? > > This is a very, very, very bad generic idea/interface. > > On which ptes is this supposed to be used? User ptes or kernel ptes? > > Surely we don't want this on user ptes. Yeah, this is only for the BPF arena PTEs which are already managed in their own way. I'd be happy to place / gate it however appropriate. Thanks. -- tejun