From patchwork Thu Oct 29 15:45:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 11866723 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AFEC7139F for ; Thu, 29 Oct 2020 15:46:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DEF62087D for ; Thu, 29 Oct 2020 15:46:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aufhR5QM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728379AbgJ2PqK (ORCPT ); Thu, 29 Oct 2020 11:46:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:49716 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727966AbgJ2PqJ (ORCPT ); Thu, 29 Oct 2020 11:46:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603986367; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc; bh=aZLvO3nbOlkXX/aM7Y/NB8twNOJTe+bO3XbdsHV0Mgw=; b=aufhR5QM9VXYiIPnhmthrlqu+fSiYl1drxkWYk55/xdegqMdOwYByy3Y7B6+noj+w8WrHf epoYAqwRATk+02wS4gKuRrF01Rn2ZJpUW9BvlOG27q0aTAuInJyoTHAeISwGWLum/ZVNTs KD+GoUfPMaB+SYiaHSTRMfiUWi4ilW8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-497-JWRKCyrPMGiGHv9J8shMMw-1; Thu, 29 Oct 2020 11:46:03 -0400 X-MC-Unique: JWRKCyrPMGiGHv9J8shMMw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EE2EA186DD24; Thu, 29 Oct 2020 15:46:00 +0000 (UTC) Received: from llong.com (ovpn-116-17.rdu2.redhat.com [10.10.116.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id B9CC25B4B9; Thu, 29 Oct 2020 15:45:53 +0000 (UTC) From: Waiman Long To: Jan Kara , Amir Goldstein Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Luca BRUNO , Waiman Long Subject: [PATCH v2] inotify: Increase default inotify.max_user_watches limit to 1048576 Date: Thu, 29 Oct 2020 11:45:35 -0400 Message-Id: <20201029154535.2074-1-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The default value of inotify.max_user_watches sysctl parameter was set to 8192 since the introduction of the inotify feature in 2005 by commit 0eeca28300df ("[PATCH] inotify"). Today this value is just too small for many modern usage. As a result, users have to explicitly set it to a larger value to make it work. After some searching around the web, these are the inotify.max_user_watches values used by some projects: - vscode: 524288 - dropbox support: 100000 - users on stackexchange: 12228 - lsyncd user: 2000000 - code42 support: 1048576 - monodevelop: 16384 - tectonic: 524288 - openshift origin: 65536 Each watch point adds an inotify_inode_mark structure to an inode to be watched. It also pins the watched inode as well as an inotify fdinfo procfs file. Modeled after the epoll.max_user_watches behavior to adjust the default value according to the amount of addressable memory available, make inotify.max_user_watches behave in a similar way to make it use no more than 1% of addressable memory within the range [8192, 1048576]. For 64-bit archs, inotify_inode_mark plus 2 inode have a size close to 2 kbytes. That means a system with 196GB or more memory should have the maximum value of 1048576 for inotify.max_user_watches. This default should be big enough for most use cases. With my x86-64 config, the size of xfs_inode, proc_inode and inotify_inode_mark is 1680 bytes. The estimated INOTIFY_WATCH_COST is 1760 bytes. [v2: increase inotify watch cost as suggested by Amir and Honza] Signed-off-by: Waiman Long --- fs/notify/inotify/inotify_user.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c index 186722ba3894..37d9f09c226f 100644 --- a/fs/notify/inotify/inotify_user.c +++ b/fs/notify/inotify/inotify_user.c @@ -37,6 +37,16 @@ #include +/* + * An inotify watch requires allocating an inotify_inode_mark structure as + * well as pinning the watched inode and adding inotify fdinfo procfs file. + * The increase in size of a filesystem inode versus a VFS inode varies + * depending on the filesystem. An extra 512 bytes is added as rough + * estimate of the additional filesystem inode cost. + */ +#define INOTIFY_WATCH_COST (sizeof(struct inotify_inode_mark) + \ + 2 * sizeof(struct inode) + 512) + /* configurable via /proc/sys/fs/inotify/ */ static int inotify_max_queued_events __read_mostly; @@ -801,6 +811,18 @@ SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) */ static int __init inotify_user_setup(void) { + unsigned int watches_max; + struct sysinfo si; + + si_meminfo(&si); + /* + * Allow up to 1% of addressible memory to be allocated for inotify + * watches (per user) limited to the range [8192, 1048576]. + */ + watches_max = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) / + INOTIFY_WATCH_COST; + watches_max = min(1048576U, max(watches_max, 8192U)); + BUILD_BUG_ON(IN_ACCESS != FS_ACCESS); BUILD_BUG_ON(IN_MODIFY != FS_MODIFY); BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB); @@ -827,7 +849,7 @@ static int __init inotify_user_setup(void) inotify_max_queued_events = 16384; init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128; - init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = 8192; + init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = watches_max; return 0; }