The patch titled Subject: fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() has been added to the -mm tree. Its filename is fs-filesystemsc-downgrade-user-reachable-warn_once-to-pr_warn_once.patch

This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/fs-filesystemsc-downgrade-user-reac... and later at http://ozlabs.org/~akpm/mmotm/broken-out/fs-filesystemsc-downgrade-user-reac...

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------------------------------------------------------ From: Eric Biggers ebiggers@google.com Subject: fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once()

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().

Link: http://lkml.kernel.org/r/20200312202552.241885-3-ebiggers@kernel.org Signed-off-by: Eric Biggers ebiggers@google.com 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

Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/filesystems.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/filesystems.c~fs-filesystemsc-downgrade-user-reachable-warn_once-to-pr_warn_once +++ a/fs/filesystems.c @@ -272,7 +272,9 @@ struct file_system_type *get_fs_type(con 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)) { _

Patches currently in -mm which might be from ebiggers@google.com are

kmod-make-request_module-return-an-error-when-autoloading-is-disabled.patch fs-filesystemsc-downgrade-user-reachable-warn_once-to-pr_warn_once.patch docs-admin-guide-document-the-kernelmodprobe-sysctl.patch selftests-kmod-test-disabling-module-autoloading.patch