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 A99D3DDAB; Sat, 12 Apr 2025 00:36:02 +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=1744418165; cv=none; b=tU7QRbovZXDJBsyf7OrQ2CIPMdJCRozouTRnrupsSYYOjEGzKQaiM9THJ/5u5/PO0336CanTItZMx7Kn2U27/m5YIscrWBbjAcglTn//k0aKILXhHQPTdVAYCUHHYes/eTlnSBM0hhmfjWjSagbUAN3CGGh3E7sq8GAd+JYEPLc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744418165; c=relaxed/simple; bh=EkLf8qvRHKf7dLC410RjIq0LNgac4pWgB/KbmwaP/74=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cE9wTsLRar3ASR8h0tzpP/eCMXFnLtinvnDYdQkR93hrsSUCDaEXqR3n1qzP61Q0dYlMdaH9vmmBlElDxdSKUWgu03Yyio5/lbFzSEFf5BlwszMCFxU/Y43Qq9uYLczeg5p+Mktza/l6QBH6X1adtZlpRSs3/CK4R+wjc1+4cRM= 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=Cp1WlN4I; 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="Cp1WlN4I" 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=jLcp1f7cOvcMEIXPWzRzzeb25u2ahPnJh9qFDKIguvo=; b=Cp1WlN4ISq7YsoEqphP6c04d4C 15BcntTpC5JcklAwoYa9UcSYoepyO8BfZpy1wE+0g8AWtNz6h6OSxPDv/o3EPzTyQvNZ/WQHfaDhv 7r3rjuFNTF08ZLTqTYy/a+JCI5l7iZCIUmB4xWCT0+3qH2dBdPlibHfpFg0QLnW/ho4FJKqhnGeyI x6z0qfH9/FmnXRRGMyJ8cZMdnxKNuEekEodSvO1ZyG/aluAJSQK5ZPZ66d7dkXtWooe2PFuFRe8mQ 3IOJl9uDfZ+oH1GxJvBDurKZSZe5GVvmXvPoX1eejHdAMmY0oe37gbbwpadx/mBXfdPGK76PDnGRd Ak0iZi+Q==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1u3Oqi-000000052MS-25TP; Sat, 12 Apr 2025 00:35:56 +0000 Date: Sat, 12 Apr 2025 01:35:56 +0100 From: Matthew Wilcox To: Gregory Price Cc: 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, donettom@linux.ibm.com, 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 Fri, Apr 11, 2025 at 08:09:55PM -0400, Gregory Price wrote: > On Sat, Apr 12, 2025 at 12:49:18AM +0100, 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. > > This wasn't a statement of approval page cache being on lower tiers, > it's a statement of fact. Enabling demotion causes this issue. Then that's the bug that needs to be fixed. Not adding 200+ lines of code to recover from a situation that should never happen.