From: Eric Biggers <ebiggers@xxxxxxxxxx> After request_module(), nothing is stopping the module from being unloaded until someone takes a reference to it via try_get_module(). The WARN_ONCE() in get_fs_type() is thus user-reachable, via userspace running 'rmmod' concurrently. Since WARN_ONCE() is for kernel bugs only, not for user-reachable situations, downgrade this warning to pr_warn_once(). Keep it printed once only, since the intent of this warning is to detect a bug in modprobe at boot time. Printing the warning more than once wouldn't really provide any useful extra information. Fixes: 41124db869b7 ("fs: warn in case userspace lied about modprobe return") Acked-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> Reviewed-by: Jessica Yu <jeyu@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # v4.13+ Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Jeff Vander Stoep <jeffv@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: NeilBrown <neilb@xxxxxxxx> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- fs/filesystems.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/filesystems.c b/fs/filesystems.c index 77bf5f95362da..90b8d879fbaf3 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -272,7 +272,9 @@ struct file_system_type *get_fs_type(const char *name) fs = __get_fs_type(name, len); if (!fs && (request_module("fs-%.*s", len, name) == 0)) { fs = __get_fs_type(name, len); - WARN_ONCE(!fs, "request_module fs-%.*s succeeded, but still no fs?\n", len, name); + if (!fs) + pr_warn_once("request_module fs-%.*s succeeded, but still no fs?\n", + len, name); } if (dot && fs && !(fs->fs_flags & FS_HAS_SUBTYPE)) { -- 2.25.1