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 EBC1C3B1B4; Sat, 29 Aug 2026 14:47:39 +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=1788014863; cv=none; b=Gak/m4awm4j8yaxwCPokbuTY2e+CYcGDtG1RX680+u+EjvoCPSHCIoNMa4iyUomCL54qR+xKuuPFGUpramdCGGMcIhHa7SaivJIZ3ioVTsyuccQlDtpLZGKyDuYXv5TEP3fkhka+w/VMXwsLT2S0bvhaSlOzj6s9om9Y+yrtDGo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788014863; c=relaxed/simple; bh=KAr+8bbwiyLK61Luj+b0j9fHioRLQNLSHQk+eb0BS6o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VWLIs+4E/Ww40F1Oid9INs72XVf8ZkSjm1cV5gJjFaSJ5JTwqtsOeguTvX/KBNZhkAnWR0/nOcPzgYJQmp+d0TMaUCOODK2BTDN7oH1hRl0odQY+YsbRpdlKtwCBHEPzG+Q5WNjUi8HB9h8Ms+Gh7QL8rZzXUOnFx4EnRnzUlcY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=c11WGKUc; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass 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="c11WGKUc" 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=451qKNGAxHR8XMQ8rJK+DM1y3GkdvqoIqzCuFMlj2JY=; b=c11WGKUc0QL+aSOLuWat6Mnz54 vyrOGredngk9WE4fBm5aLGD4kX7pz0aYwyq0oalgHkgJBFFUWJJ0EohzJjFanrGdKw7agomkxuk3R NugGYXt4VvtntimIGrpChZWS068W/yZlcr3a/zfPTYQ0DA425LuE+LPl9b16ZtSNLx8EqIgZNHx6e dOpHizf0Wyn2UR7uq04FGbT5sYcPFo6QOj2cXBbBMVHCZ0+tS9lB9fGUtPgTM6UU16S4TkHSXyZY6 YQU9f9GmRZnNfzw9kRUNueg0JsW5yLJBcbO/CgL2AQ+8xsBJXYPe0HX0J1pDvBxpi7dy7qr3nYse0 ep1DJ5TA==; Received: from willy by casper.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1x0KLH-0000000Gbt5-16nI; Sat, 29 Aug 2026 14:47:35 +0000 Date: Sat, 29 Aug 2026 15:47:35 +0100 From: Matthew Wilcox To: Wenjie Qi Cc: jack@suse.cz, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, baohua@kernel.org, axboe@kernel.dk, trond.myklebust@hammerspace.com, qiwenjie@xiaomi.com Subject: Re: [PATCH v2] mm: filemap: retain mapped dropbehind folios Message-ID: References: <20260820142956.1414337-1-qiwenjie@xiaomi.com> <3fa43eaca792bc0bbde4b82a6c1fcdd3f528b398.1787999152.git.qiwenjie@xiaomi.com> 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: <3fa43eaca792bc0bbde4b82a6c1fcdd3f528b398.1787999152.git.qiwenjie@xiaomi.com> On Sat, Aug 29, 2026 at 08:30:47PM +0800, Wenjie Qi wrote: > From: Wenjie Qi > > Fault-around can map ready dropbehind folios without going through the > normal page-cache lookup that clears dropbehind. A mapping represents a > competing cached user, so retain the folio instead of forcibly unmapping it > when writeback completes. > > Unmapped dropbehind folios continue through the existing invalidation path. Yes, I think this is the right approach. Reviewed-by: Matthew Wilcox (Oracle)