From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 84B0918E3F; Sun, 13 Apr 2025 12:48:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744548524; cv=none; b=C2KuQOk9hHxjgbNQlzLe/UIlOQYdBPpIaFgK2hHeQqRjCfvji+/NuPFrKV6OWmKN3XtL6NEWxKxX3lkfxx3yEFGP1aMrWYTMbayPOTVtqmndRh5C7cNBJtx2+fBYxlBRYlaVQ4IdL3HuBTrXV3r3C/X3E40y9QDfUKOYFUVeMOU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744548524; c=relaxed/simple; bh=inTSUzpY4HkgLJjo5Y9sPgarm2uGUrVEaFbir5x5xiE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TJiYPBKoejavyRJoY1e0pFvb0ewNYJ8e4Wdpc5DN1pyikxfTVD85EckkHW858Fvqi3L61zQeut66/++rCdkZIzK/xnVHaURaWvGXRb5HBdTIUlYXhAdYt1pEksyae7QQsqg7MB6YyIdXytg/pa4v3IkHKBs7SW1MvOAoh5Z25mY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=SGufiG16; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SGufiG16" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=BYd9ghzIbvgBQxn74x2yQL2hqEOdpaPt3okp+tYy+YI=; b=SGufiG16PzYig2XsU0/e5Eg5VY Nrz1kUIZf1J4TK69G0cSJe88bZuAFUerzAYATIWklMfuyBy4evF9LW3qlxdb+o+zZCdfFGVTeniUK hl0Hi7DdUVsKYEAcu/47Gf1HK+3N4KGc5bvAmePpdih0gKpX9X4LwBR3g3vMsr//bmQUZVWp4g1pz GVWbgGoEAhrwg4HJCxlh+1lCzdaKxnHWVgkEdrDimsA9bryaMCCLZMixbN0PZeJ9YZo2gClBAUMAr 6xyHlkg+FWPhMKZ2mMr6rYCTze1Bijcfaf+c/87MnHxgKTJZbXC9SKGCNHaahwveAINGGXaUYaGcP dSH+632Q==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1u3wl8-00000006o5h-3PQP; Sun, 13 Apr 2025 12:48:26 +0000 Date: Sun, 13 Apr 2025 13:48:26 +0100 From: Matthew Wilcox To: Donet Tom Cc: Gregory Price , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, Huang Ying , Keith Busch , Feng Tang , Neha Gholkar Subject: Re: [RFC PATCH v4 0/6] Promotion of Unmapped Page Cache Folios. Message-ID: References: <20250411221111.493193-1-gourry@gourry.net> 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: On Sun, Apr 13, 2025 at 10:53:48AM +0530, Donet Tom wrote: > > On 4/12/25 5:19 AM, Matthew Wilcox wrote: > > On Fri, Apr 11, 2025 at 06:11:05PM -0400, Gregory Price wrote: > > > Unmapped page cache pages can be demoted to low-tier memory, but > > No. Page cache should never be demoted to low-tier memory. > > NACK this patchset. > > Hi Mathew, > > I have one doubt. Under memory pressure, page cache allocations can > fall back to lower-tier memory, right? So later, if those page cache pages > become hot, shouldn't we promote them? That shouldn't happen either. CXL should never be added to the page allocator. You guys are creating a lot of problems for yourselves, and I've been clear that I want no part of this. >