From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout12.his.huawei.com (canpmsgout12.his.huawei.com [113.46.200.227]) (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 715BB312834 for ; Fri, 27 Feb 2026 07:32:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.227 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772177546; cv=none; b=BDsi8RajgtdPNw1HSDKXOMMlOPXqpQBoqycwMYZPS620aRQhi6XmFzXl5qbzJFk+d1JP0dLj+yJO81sNetvU9hH3mayuwF8/2kKa+Lxl9AqQbQ9gf/EfRJkN0cnORuT58d/v1D8Hmcs/5rMRpncgVdRZlnbq6zfkqoUX/inuuwU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772177546; c=relaxed/simple; bh=SPNIQA+GKLplRlFizdkTFwJaZwdHs95U6E48McN20io=; h=Subject:To:References:CC:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=tX+MIqhEsdZKjXGwqXH29Zzk7MlrSCYVoPZbpqcTH8OFcd9WN6QnbcMsaJq1NDv/2HpCzpaCQXjjKrsqhCv+VxNzLH5l0gi6w+9MXn5z6YYGgTeZNbU9anwkkV4xNjEOxwULAJywrcM2i5aJGbW8rNqq8RXepqCGW/SvcbN06QI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=xibT8yrp; arc=none smtp.client-ip=113.46.200.227 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="xibT8yrp" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=FtzP6snTxb6/9Yfh1EYbBMx18ST1cVCB8Di30/9yAaI=; b=xibT8yrpFyU5r1CHGZu7/2XwE3lL+8Sbz4s+zuFFVzXR8JG966qwAOjSfWgOSwBL3YE1MAgQf 8at/jTqnnkYjvaopov8TZGf2tG7AtcQ6Um8eFr4tCq5ompNGPvrlqF7zZpvcW9qGOdYVvuP9z4J 3hbrU2Cq4F0E8vt7JmSsC/Y= Received: from mail.maildlp.com (unknown [172.19.163.200]) by canpmsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4fMfzw4XzkznTWJ; Fri, 27 Feb 2026 15:27:40 +0800 (CST) Received: from dggemv712-chm.china.huawei.com (unknown [10.1.198.32]) by mail.maildlp.com (Postfix) with ESMTPS id 3F2B94055B; Fri, 27 Feb 2026 15:32:20 +0800 (CST) Received: from kwepemq500016.china.huawei.com (7.202.194.202) by dggemv712-chm.china.huawei.com (10.1.198.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 27 Feb 2026 15:32:20 +0800 Received: from [10.174.178.185] (10.174.178.185) by kwepemq500016.china.huawei.com (7.202.194.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 27 Feb 2026 15:32:19 +0800 Subject: Re: [PATCH v3 0/3] add support for drop_caches for individual filesystem To: Muchun Song References: <20260227025548.2252380-1-yebin@huaweicloud.com> <4FDE845E-BDD6-45FE-98FA-40ABAF62608B@linux.dev> <69A13C1A.9020002@huawei.com> <959B7A5C-8C1A-417C-A1D3-6500E506DEE6@linux.dev> CC: Ye Bin , , , , , , , , , From: "yebin (H)" Message-ID: <69A14882.4030609@huawei.com> Date: Fri, 27 Feb 2026 15:32:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <959B7A5C-8C1A-417C-A1D3-6500E506DEE6@linux.dev> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To kwepemq500016.china.huawei.com (7.202.194.202) On 2026/2/27 14:55, Muchun Song wrote: > > >> On Feb 27, 2026, at 14:39, yebin (H) wrote: >> >> >> >> On 2026/2/27 11:31, Muchun Song wrote: >>> >>> >>>> On Feb 27, 2026, at 10:55, Ye Bin wrote: >>>> >>>> From: Ye Bin >>>> >>>> In order to better analyze the issue of file system uninstallation caused >>>> by kernel module opening files, it is necessary to perform dentry recycling >>>> on a single file system. But now, apart from global dentry recycling, it is >>>> not supported to do dentry recycling on a single file system separately. >>> >>> Would shrinker-debugfs satisfy your needs (See Documentation/admin-guide/mm/shrinker_debugfs.rst)? >>> >>> Thanks, >>> Muchun >>> >> Thank you for the reminder. The reclamation of dentries and nodes can meet my needs. However, the reclamation of the page cache alone does not satisfy my requirements. I have reviewed the code of shrinker_debugfs_scan_write() and found that it does not support batch deletion of all dentries/inode for all nodes/memcgs,instead, users need to traverse through them one by one, which is not very convenient. Based on my previous experience, I have always performed dentry/inode reclamation at the file system level. > > I don't really like that you're implementing another mechanism with duplicate > functionality. If you'd like, you could write a script to iterate through them > and execute it that way—I don't think that would be particularly inconvenient, > would it? If the iteration operation of memcg is indeed quite cumbersome, I > think extending the shrinker debugfs functionality would be more appropriate. > The shrinker_debugfs can be extended to support node/memcg/fs granularity reclamation, similar to the extended function of echo " 0 - X" > count /echo " - 0 X" > count /echo " - - X" > count. This only solves the problem of reclaiming dentries/inode based on a single file system. However, the page cache reclamation based on a single file system cannot be implemented by using shrinker_debugfs. If the extended function is implemented by shrinker_debugfs, drop_fs_caches can reuse the same interface and maintain the same semantics as drop_caches. >> >> Thanks, >> Ye Bin >>>> This feature has usage scenarios in problem localization scenarios.At the >>>> same time, it also provides users with a slightly fine-grained >>>> pagecache/entry recycling mechanism. >>>> This patchset supports the recycling of pagecache/entry for individual file >>>> systems. >>>> >>>> Diff v3 vs v2 >>>> 1. Introduce introduce drop_sb_dentry_inode() helper instead of >>>> reclaim_dcache_sb()/reclaim_icache_sb() helper for reclaim dentry/inode. >>>> 2. Fixing compilation issues in specific architectures and configurations. >>>> >>>> Diff v2 vs v1: >>>> 1. Fix possible live lock for shrink_icache_sb(). >>>> 2. Introduce reclaim_dcache_sb() for reclaim dentry. >>>> 3. Fix potential deadlocks as follows: >>>> https://lore.kernel.org/linux-fsdevel/00000000000098f75506153551a1@google.com/ >>>> After some consideration, it was decided that this feature would primarily >>>> be used for debugging purposes. Instead of adding a new IOCTL command, the >>>> task_work mechanism was employed to address potential deadlock issues. >>>> >>>> Ye Bin (3): >>>> mm/vmscan: introduce drop_sb_dentry_inode() helper >>>> sysctl: add support for drop_caches for individual filesystem >>>> Documentation: add instructions for using 'drop_fs_caches sysctl' >>>> sysctl >>>> >>>> Documentation/admin-guide/sysctl/vm.rst | 44 +++++++++ >>>> fs/drop_caches.c | 125 ++++++++++++++++++++++++ >>>> include/linux/mm.h | 1 + >>>> mm/internal.h | 3 + >>>> mm/shrinker.c | 4 +- >>>> mm/vmscan.c | 50 ++++++++++ >>>> 6 files changed, 225 insertions(+), 2 deletions(-) >>>> >>>> -- >>>> 2.34.1 >>>> >>> >>> . >>> > > . >