]> git.ipfire.org Git - thirdparty/kernel/stable.git/commitdiff
smb: Log an error when close_all_cached_dirs fails
authorPaul Aurich <paul@darkrain42.org>
Wed, 20 Nov 2024 16:01:54 +0000 (08:01 -0800)
committerSteve French <stfrench@microsoft.com>
Sat, 21 Jun 2025 16:03:25 +0000 (11:03 -0500)
Under low-memory conditions, close_all_cached_dirs() can't move the
dentries to a separate list to dput() them once the locks are dropped.
This will result in a "Dentry still in use" error, so add an error
message that makes it clear this is what happened:

[  495.281119] CIFS: VFS: \\otters.example.com\share Out of memory while dropping dentries
[  495.281595] ------------[ cut here ]------------
[  495.281887] BUG: Dentry ffff888115531138{i=78,n=/}  still in use (2) [unmount of cifs cifs]
[  495.282391] WARNING: CPU: 1 PID: 2329 at fs/dcache.c:1536 umount_check+0xc8/0xf0

Also, bail out of looping through all tcons as soon as a single
allocation fails, since we're already in trouble, and kmalloc() attempts
for subseqeuent tcons are likely to fail just like the first one did.

Signed-off-by: Paul Aurich <paul@darkrain42.org>
Acked-by: Bharath SM <bharathsm@microsoft.com>
Suggested-by: Ruben Devos <rdevos@oxya.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
fs/smb/client/cached_dir.c

index 5200a0f3cafc6fd1ef8959859384dfedbbeb2172..368e870624dac69c27531a2016d04fc23f18129c 100644 (file)
@@ -509,8 +509,17 @@ void close_all_cached_dirs(struct cifs_sb_info *cifs_sb)
                spin_lock(&cfids->cfid_list_lock);
                list_for_each_entry(cfid, &cfids->entries, entry) {
                        tmp_list = kmalloc(sizeof(*tmp_list), GFP_ATOMIC);
-                       if (tmp_list == NULL)
-                               break;
+                       if (tmp_list == NULL) {
+                               /*
+                                * If the malloc() fails, we won't drop all
+                                * dentries, and unmounting is likely to trigger
+                                * a 'Dentry still in use' error.
+                                */
+                               cifs_tcon_dbg(VFS, "Out of memory while dropping dentries\n");
+                               spin_unlock(&cfids->cfid_list_lock);
+                               spin_unlock(&cifs_sb->tlink_tree_lock);
+                               goto done;
+                       }
                        spin_lock(&cfid->fid_lock);
                        tmp_list->dentry = cfid->dentry;
                        cfid->dentry = NULL;
@@ -522,6 +531,7 @@ void close_all_cached_dirs(struct cifs_sb_info *cifs_sb)
        }
        spin_unlock(&cifs_sb->tlink_tree_lock);
 
+done:
        list_for_each_entry_safe(tmp_list, q, &entry, entry) {
                list_del(&tmp_list->entry);
                dput(tmp_list->dentry);