6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paul Aurich paul@darkrain42.org
commit a2182743a8b4969481f64aec4908ff162e8a206c upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/cached_dir.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
--- a/fs/smb/client/cached_dir.c +++ b/fs/smb/client/cached_dir.c @@ -484,8 +484,17 @@ void close_all_cached_dirs(struct cifs_s 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; @@ -497,6 +506,7 @@ void close_all_cached_dirs(struct cifs_s } 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);