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 25FCECCA47C for ; Mon, 4 Jul 2022 01:10:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229505AbiGDBKK (ORCPT ); Sun, 3 Jul 2022 21:10:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231403AbiGDBJt (ORCPT ); Sun, 3 Jul 2022 21:09:49 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EAE3662F5 for ; Sun, 3 Jul 2022 18:09:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 894F06130E for ; Mon, 4 Jul 2022 01:09:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD6AAC341C6; Mon, 4 Jul 2022 01:09:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1656896987; bh=L3xqCoCIaz0fP5DubZx2uYiFI1JSt4e9wtHRho9w0g4=; h=Date:To:From:Subject:From; b=PhgfdzkN/pC89IbkxSWTzAJssgCLpJ+5cJ43OFP5wuGSq00zsUXUuTSohkDy48jW0 Z8DGr/Ny5t/d6zvQ8ny9F9xkbBiu0hFedQ5xdKedO+8tXQ5/S4X6oiR0qbMUoYo3D5 il39s1T8KKwsQ1Iryr10WQACllh7w6qTTnijMzGg= Date: Sun, 03 Jul 2022 18:09:46 -0700 To: mm-commits@vger.kernel.org, songmuchun@bytedance.com, kent.overstreet@gmail.com, hdanton@sina.com, dchinner@redhat.com, christophe.jaillet@wanadoo.fr, roman.gushchin@linux.dev, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-shrinkers-add-scan-interface-for-shrinker-debugfs.patch removed from -mm tree Message-Id: <20220704010946.DD6AAC341C6@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm: shrinkers: add scan interface for shrinker debugfs has been removed from the -mm tree. Its filename was mm-shrinkers-add-scan-interface-for-shrinker-debugfs.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Roman Gushchin Subject: mm: shrinkers: add scan interface for shrinker debugfs Date: Tue, 31 May 2022 20:22:27 -0700 Add a scan interface which allows to trigger scanning of a particular shrinker and specify memcg and numa node. It's useful for testing, debugging and profiling of a specific scan_objects() callback. Unlike alternatives (creating a real memory pressure and dropping caches via /proc/sys/vm/drop_caches) this interface allows to interact with only one shrinker at once. Also, if a shrinker is misreporting the number of objects (as some do), it doesn't affect scanning. [roman.gushchin@linux.dev: improve typing, fix arg count checking] Link: https://lkml.kernel.org/r/YpgKttTowT22mKPQ@carbon [akpm@linux-foundation.org: fix arg count checking] Link: https://lkml.kernel.org/r/20220601032227.4076670-7-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin Acked-by: Muchun Song Cc: Christophe JAILLET Cc: Dave Chinner Cc: Hillf Danton Cc: Kent Overstreet Signed-off-by: Andrew Morton --- Documentation/admin-guide/mm/shrinker_debugfs.rst | 39 +++++- mm/shrinker_debug.c | 74 ++++++++++++ 2 files changed, 109 insertions(+), 4 deletions(-) --- a/Documentation/admin-guide/mm/shrinker_debugfs.rst~mm-shrinkers-add-scan-interface-for-shrinker-debugfs +++ a/Documentation/admin-guide/mm/shrinker_debugfs.rst @@ -5,14 +5,16 @@ Shrinker Debugfs Interface ========================== Shrinker debugfs interface provides a visibility into the kernel memory -shrinkers subsystem and allows to get information about individual shrinkers. +shrinkers subsystem and allows to get information about individual shrinkers +and interact with them. For each shrinker registered in the system a directory in **/shrinker/** is created. The directory's name is composed from the shrinker's name and an unique id: e.g. *kfree_rcu-0* or *sb-xfs:vda1-36*. -Each shrinker directory contains the **count** file, which allows to trigger -the *count_objects()* callback for each memcg and numa node (if applicable). +Each shrinker directory contains **count** and **scan** files, which allow to +trigger *count_objects()* and *scan_objects()* callbacks for each memcg and +numa node (if applicable). Usage: ------ @@ -43,7 +45,7 @@ Usage: $ cd sb-btrfs\:vda2-24/ $ ls - count + count scan 3. *Count objects* @@ -102,3 +104,32 @@ Usage: 2877 84 0 293 1 0 735 8 0 + +4. *Scan objects* + + The expected input format:: + + + + For a non-memcg-aware shrinker or on a system with no memory + cgrups **0** should be passed as cgroup id. + :: + + $ cd /sys/kernel/debug/shrinker/ + $ cd sb-btrfs\:vda2-24/ + + $ cat count | head -n 5 + 1 212 0 + 21 97 0 + 55 802 5 + 2367 2 0 + 225 13 0 + + $ echo "55 0 200" > scan + + $ cat count | head -n 5 + 1 212 0 + 21 96 0 + 55 752 5 + 2367 2 0 + 225 13 0 --- a/mm/shrinker_debug.c~mm-shrinkers-add-scan-interface-for-shrinker-debugfs +++ a/mm/shrinker_debug.c @@ -99,6 +99,78 @@ static int shrinker_debugfs_count_show(s } DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_count); +static int shrinker_debugfs_scan_open(struct inode *inode, struct file *file) +{ + file->private_data = inode->i_private; + return nonseekable_open(inode, file); +} + +static ssize_t shrinker_debugfs_scan_write(struct file *file, + const char __user *buf, + size_t size, loff_t *pos) +{ + struct shrinker *shrinker = file->private_data; + unsigned long nr_to_scan = 0, ino, read_len; + struct shrink_control sc = { + .gfp_mask = GFP_KERNEL, + }; + struct mem_cgroup *memcg = NULL; + int nid; + char kbuf[72]; + ssize_t ret; + + read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1); + if (copy_from_user(kbuf, buf, read_len)) + return -EFAULT; + kbuf[read_len] = '\0'; + + if (sscanf(kbuf, "%lu %d %lu", &ino, &nid, &nr_to_scan) != 3) + return -EINVAL; + + if (nid < 0 || nid >= nr_node_ids) + return -EINVAL; + + if (nr_to_scan == 0) + return size; + + if (shrinker->flags & SHRINKER_MEMCG_AWARE) { + memcg = mem_cgroup_get_from_ino(ino); + if (!memcg || IS_ERR(memcg)) + return -ENOENT; + + if (!mem_cgroup_online(memcg)) { + mem_cgroup_put(memcg); + return -ENOENT; + } + } else if (ino != 0) { + return -EINVAL; + } + + ret = down_read_killable(&shrinker_rwsem); + if (ret) { + mem_cgroup_put(memcg); + return ret; + } + + sc.nid = nid; + sc.memcg = memcg; + sc.nr_to_scan = nr_to_scan; + sc.nr_scanned = nr_to_scan; + + shrinker->scan_objects(shrinker, &sc); + + up_read(&shrinker_rwsem); + mem_cgroup_put(memcg); + + return size; +} + +static const struct file_operations shrinker_debugfs_scan_fops = { + .owner = THIS_MODULE, + .open = shrinker_debugfs_scan_open, + .write = shrinker_debugfs_scan_write, +}; + int shrinker_debugfs_add(struct shrinker *shrinker) { struct dentry *entry; @@ -128,6 +200,8 @@ int shrinker_debugfs_add(struct shrinker debugfs_create_file("count", 0220, entry, shrinker, &shrinker_debugfs_count_fops); + debugfs_create_file("scan", 0440, entry, shrinker, + &shrinker_debugfs_scan_fops); return 0; } _ Patches currently in -mm which might be from roman.gushchin@linux.dev are mm-memcontrol-do-not-miss-memcg_max-events-for-enforced-allocations.patch