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 5404A362138; Thu, 30 Apr 2026 04:47:12 +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=1777524432; cv=none; b=ZjDGKvqqeAYAh+N0El25I44V79M9zF2kZFAAhzJl7iR1Hhcu0FuvjgFYuORjxkgH/AJRo4YaG0nNyaTee+VgCHVGIEQLnup7RlHYpnemz58wwHZfhXlBcrdFrkdwFU95bWiR4b7JhLKXNHGu47KiOPEnpwksJpXU4TSVhLGN+C0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777524432; c=relaxed/simple; bh=E/yh7MssMqbKR24sqcd/16bJQwoqXO9idoUrqSRK92E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=PCZ85269bV72fW0ptIr3wgVpjbqtnPqKP9YZ0Rsx28sAcQ1OS5JjKZfwwg4DuVAn1a2m1gPUiW7w61zb13HZomdjzJ7dprlklk/0jFstyUcrpUjvKwBu3rjFzk2MUF3JdrPnzAo7HNYipAXVpYMmw/Rhx9LEgfXjsn8YraXXE0s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YqT6uRgQ; 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="YqT6uRgQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F372C2BCB8; Thu, 30 Apr 2026 04:47:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777524432; bh=E/yh7MssMqbKR24sqcd/16bJQwoqXO9idoUrqSRK92E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YqT6uRgQeiMgV6LaXGJpu+ONELl49SC1EESjimSweN54pm/XOyeUMK3m8LaD1GWMo LqyirD+d0LA4s8Sf59sVojGYlYUx+kuWYJtcKuhpTxJuScImz54+YifA+yrUPoCb73 yS8wkF9qtOED4THBT5voqlNs/EzTm7dlaBBimJmnNp8ZIvu/8d1RVlSEl+R8KMrfq2 9WGb+aOyqTYy9sE0DJWFIgLnFRZtaq+L1vzivbh7tvKMpjLedrUQguWpjf6TjvEJuy 3LlTyJxkrH7CM9wVks8DBi282OwhAGAdDxtnoN9yHOoD2gsAw4QtIoPPQ4BtzAPyDD 8t0UkHsCtZLxQ== From: SeongJae Park To: "Kiryl Shutsemau (Meta)" Cc: SeongJae Park , akpm@linux-foundation.org, rppt@kernel.org, peterx@redhat.com, david@kernel.org, ljs@kernel.org, surenb@google.com, vbabka@kernel.org, Liam.Howlett@oracle.com, ziy@nvidia.com, corbet@lwn.net, skhan@linuxfoundation.org, seanjc@google.com, pbonzini@redhat.com, jthoughton@google.com, aarcange@redhat.com, usama.arif@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH 01/14] mm: decouple protnone helpers from CONFIG_NUMA_BALANCING Date: Wed, 29 Apr 2026 21:47:02 -0700 Message-ID: <20260430044703.77862-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260427114607.4068647-2-kas@kernel.org> References: 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=UTF-8 Content-Transfer-Encoding: 8bit On Mon, 27 Apr 2026 12:45:49 +0100 "Kiryl Shutsemau (Meta)" wrote: > pte_protnone() and pmd_protnone() detect present-but-inaccessible page > table entries. This capability is useful beyond NUMA balancing — for > example, userfaultfd working set tracking uses protnone PTEs to track > page access without unmapping pages. I agree. It can be useful for general access monitoring. I'm also slowly but continuously working [1] to use that for DAMON. > > Introduce CONFIG_ARCH_HAS_PTE_PROTNONE to decouple the protnone PTE > infrastructure from CONFIG_NUMA_BALANCING. The six architectures that > support protnone PTEs (x86_64, arm64, powerpc, s390, riscv, loongarch) > now select this option, and CONFIG_NUMA_BALANCING depends on it. > > No functional change — the same set of architectures continues to have > working protnone support, but the infrastructure is now available > independently of NUMA balancing. I think this is a good change for making the infrastructure available for uffd. I believe this can also be useful for making it further available for general access monitoring purposes. I hope this to be landed on the mainline sooner than later. Thank you for doing this, Kiryl! > > Signed-off-by: Kiryl Shutsemau (Meta) > Assisted-by: Claude:claude-opus-4-6 Acked-by: SeongJae Park [1] https://lore.kernel.org/linux-mm/20260218054320.4570-1-sj@kernel.org/ Thanks, SJ [...]