From: Eric Biggers <ebiggers@google.com> commit 26c5d78c976ca298e59a56f6101a97b618ba3539 upstream. 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") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jessica Yu <jeyu@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: NeilBrown <neilb@suse.com> Cc: <stable@vger.kernel.org> [4.13+] Link: http://lkml.kernel.org/r/20200312202552.241885-3-ebiggers@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/filesystems.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/filesystems.c b/fs/filesystems.c index b03f57b..181200d 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -267,7 +267,9 @@ 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)) { -- 1.8.3