From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C5F5C64EC4 for ; Wed, 8 Mar 2023 21:31:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229776AbjCHVbD (ORCPT ); Wed, 8 Mar 2023 16:31:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229492AbjCHVbA (ORCPT ); Wed, 8 Mar 2023 16:31:00 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 04D6C14EBE for ; Wed, 8 Mar 2023 13:30:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=IzQFIWT46znk5i0D+MsYj76CTFCg/0EZ16e6Y2m5SD0=; b=3w3cdJetO/jogLTcUKjz0RGSni IUo2+CUDSUDwyw1g5lIuMk93u9eS7FEdD66wbpagj57lKjufAMc7CxPIUqtTeQN8iBMftrOKARX4D 8GprGyZL33+5LqB7mcTudokFAGvCDq9AU6ZyA9bKQSjgUS3iI/5Dajy4PmuuJaOrf0uIN74Ga1raI WQ3/7sV5LzeIlXx+GZSslVjv8KtL6eq7hh+OsX+fm/dv+qEj2fPc1hWmY2KNr8JAgc7Y2pdO161nM ONJc4YluOrPm0G+S/VeqCvSf97P7aDdqHlO2uXTWTxRniKRGfc7uxGXmAayHNlgCNxG1bNH+00OeP gpQrA7tQ==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pa1My-006qYJ-C6; Wed, 08 Mar 2023 21:30:44 +0000 Date: Wed, 8 Mar 2023 13:30:44 -0800 From: Luis Chamberlain To: David Hildenbrand Cc: hughd@google.com, akpm@linux-foundation.org, willy@infradead.org, brauner@kernel.org, linux-mm@kvack.org, p.raghav@samsung.com, da.gomez@samsung.com, a.manzanares@samsung.com, dave@stgolabs.net, yosryahmed@google.com, keescook@chromium.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/6] shmem: move reclaim check early on writepages() Message-ID: References: <20230302232758.888157-1-mcgrof@kernel.org> <20230302232758.888157-4-mcgrof@kernel.org> <2a3386e7-9b09-f22e-ee39-a37a046d54ec@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2a3386e7-9b09-f22e-ee39-a37a046d54ec@redhat.com> Sender: Luis Chamberlain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 06, 2023 at 03:01:52PM +0100, David Hildenbrand wrote: > On 03.03.23 00:27, Luis Chamberlain wrote: > > @@ -1340,6 +1340,18 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) > > swp_entry_t swap; > > pgoff_t index; > > + /* > > + * Our capabilities prevent regular writeback or sync from ever calling > > + * shmem_writepage; but a stacking filesystem might use ->writepage of > > + * its underlying filesystem, in which case tmpfs should write out to > > + * swap only in response to memory pressure, and not for the writeback > > + * threads or sync. > > + */ > > + if (!wbc->for_reclaim) { > > if (WARN_ON_ONCE(!wbc->for_reclaim)) > > > + WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ > > And drop the comment :) That's what WARN_ON_ONCE is all about. Good call, will add that to v2. > Acked-by: David Hildenbrand Great thanks, Luis