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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5CDFC433EF for ; Tue, 22 Mar 2022 20:42:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4E3DD6B0071; Tue, 22 Mar 2022 16:42:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 491B26B0072; Tue, 22 Mar 2022 16:42:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 35A346B0074; Tue, 22 Mar 2022 16:42:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0002.hostedemail.com [216.40.44.2]) by kanga.kvack.org (Postfix) with ESMTP id 23F806B0071 for ; Tue, 22 Mar 2022 16:42:04 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id D1A65182751A4 for ; Tue, 22 Mar 2022 20:42:03 +0000 (UTC) X-FDA: 79273194126.27.D403594 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf05.hostedemail.com (Postfix) with ESMTP id 69D7E100036 for ; Tue, 22 Mar 2022 20:42:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=VVdPJvP8CTmA6uCU7BHeBGm/i6I2iUb5gLPuoYQG+lU=; b=jn9DyNFw2YYcG+K2n52e1ftzfB fbXds5OckFD4M8BO1yK6inWZnpMCk3ZQ7AzjiAhouiyhLLugNcTonjBW5hWcyzm9ZFzmj971KJkwT opZEm0E47Jaj5+/pg/8E+GerszS5qcKxRDfeLqaOi/G6EJ6wRRCFRdrK3kc9JUUCS8nALLJt05XyW fWYc0MI1ddjul0zVTG6Nc8b6lzSFv5uv/6ApaHx5fa3C+W5RQQZFzZQESqd0DAeJgYLfWg6jgu8Nd T/7Fdkf+OP7V0ByephrSDyla5EKywI2dVbET7XHisXz3at7yiTqB7/2fM5Q0RtBmktYY44OfdXw+N +r5cVMeA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nWlKG-00BvCw-47; Tue, 22 Mar 2022 20:41:56 +0000 Date: Tue, 22 Mar 2022 20:41:56 +0000 From: Matthew Wilcox To: Roman Gushchin Cc: Stephen Brennan , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Gautham Ananthakrishna , khlebnikov@yandex-team.ru Subject: Re: [LSF/MM TOPIC] Better handling of negative dentries Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 69D7E100036 X-Stat-Signature: ioffidkngaisy5o3f4u494wjng8jxw5m Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=jn9DyNFw; dmarc=none; spf=none (imf05.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspam-User: X-HE-Tag: 1647981723-345775 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000702, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Mar 15, 2022 at 01:56:18PM -0700, Roman Gushchin wrote: > I=E2=80=99d be happy to join this discussion. And in my opinion it=E2=80= =99s going > beyond negative dentries: there are other types of objects which tend > to grow beyond any reasonable limits if there is no memory pressure. > > A perfect example when it happens is when a machine is almost idle > for some period of time. Periodically running processes creating > various kernel objects (mostly vfs cache) which over time are filling > significant portions of the total memory. And when the need for memory > arises, we realize that the memory is heavily fragmented and it=E2=80=99= s > costly to reclaim it back. When you say "vfs cache", do you mean page cache, inode cache, or something else?