linux-kernel - [PATCH] netfs: Delete subtree of 'fs/netfs' when netfs module exits

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Message-Id: <20240826113404.3214786-1-libaokun@huaweicloud.com>
Date: Mon, 26 Aug 2024 19:34:04 +0800
From: libaokun@...weicloud.com
To: netfs@...ts.linux.dev,
	dhowells@...hat.com,
	jlayton@...nel.org
Cc: hsiangkao@...ux.alibaba.com,
	jefflexu@...ux.alibaba.com,
	linux-erofs@...ts.ozlabs.org,
	brauner@...nel.org,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	libaokun@...weicloud.com,
	yangerkun@...wei.com,
	houtao1@...wei.com,
	yukuai3@...wei.com,
	wozizhi@...wei.com,
	Baokun Li <libaokun1@...wei.com>,
	stable@...nel.org
Subject: [PATCH] netfs: Delete subtree of 'fs/netfs' when netfs module exits

From: Baokun Li <libaokun1@...wei.com>

In netfs_init() or fscache_proc_init(), we create dentry under 'fs/netfs',
but in netfs_exit(), we only delete the proc entry of 'fs/netfs' without
deleting its subtree. This triggers the following WARNING:

==================================================================
remove_proc_entry: removing non-empty directory 'fs/netfs', leaking at least 'requests'
WARNING: CPU: 4 PID: 566 at fs/proc/generic.c:717 remove_proc_entry+0x160/0x1c0
Modules linked in: netfs(-)
CPU: 4 UID: 0 PID: 566 Comm: rmmod Not tainted 6.11.0-rc3 #860
RIP: 0010:remove_proc_entry+0x160/0x1c0
Call Trace:
 <TASK>
 netfs_exit+0x12/0x620 [netfs]
 __do_sys_delete_module.isra.0+0x14c/0x2e0
 do_syscall_64+0x4b/0x110
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
==================================================================

Therefore use remove_proc_subtree instead() of remove_proc_entry() to
fix the above problem.

Fixes: 7eb5b3e3a0a5 ("netfs, fscache: Move /proc/fs/fscache to /proc/fs/netfs and put in a symlink")
Cc: stable@...nel.org
Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
 fs/netfs/main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/netfs/main.c b/fs/netfs/main.c
index 5f0f438e5d21..9d6b49dc6694 100644
--- a/fs/netfs/main.c
+++ b/fs/netfs/main.c
@@ -142,7 +142,7 @@ static int __init netfs_init(void)
 
 error_fscache:
 error_procfile:
-	remove_proc_entry("fs/netfs", NULL);
+	remove_proc_subtree("fs/netfs", NULL);
 error_proc:
 	mempool_exit(&netfs_subrequest_pool);
 error_subreqpool:
@@ -159,7 +159,7 @@ fs_initcall(netfs_init);
 static void __exit netfs_exit(void)
 {
 	fscache_exit();
-	remove_proc_entry("fs/netfs", NULL);
+	remove_proc_subtree("fs/netfs", NULL);
 	mempool_exit(&netfs_subrequest_pool);
 	kmem_cache_destroy(netfs_subrequest_slab);
 	mempool_exit(&netfs_request_pool);
-- 
2.39.2