On Sat, May 27, 2017 at 07:01:45PM -0700, Jessica Yu wrote: > +++ Luis R. Rodriguez [25/05/17 17:44 -0700]: > > kmod <= v19 was broken -- it could return 0 to modprobe calls, > > incorrectly assuming that a kernel module was built-in, whereas in > > reality the module was just forming in the kernel. The reason for this > > is an incorrect userspace heuristics. A userspace kmod fix is available > > for it [0], however should userspace break again we could go on with > > an failed get_fs_type() which is hard to debug as the request_module() > > is detected as returning 0. The first suspect would be that there is > > something worth with the kernel's module loader and obviously in this > > case that is not the issue. > > > > Since these issues are painful to debug complain when we know userspace > > has outright lied to us. > > > > [0] http://git.kernel.org/cgit/utils/kernel/kmod/kmod.git/commit/libkmod/libkmod-module.c?id=fd44a98ae2eb5eb32161088954ab21e58e19dfc4 > > > > Suggested-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx> > > Cc: Jessica Yu <jeyu@xxxxxxxxxx> > > Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx> > > --- > > fs/filesystems.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/filesystems.c b/fs/filesystems.c > > index cac75547d35c..0f477a5de6ea 100644 > > --- a/fs/filesystems.c > > +++ b/fs/filesystems.c > > @@ -275,8 +275,10 @@ struct file_system_type *get_fs_type(const char *name) > > int len = dot ? dot - name : strlen(name); > > > > fs = __get_fs_type(name, len); > > - if (!fs && (request_module("fs-%.*s", len, name) == 0)) > > + if (!fs && (request_module("fs-%.*s", len, name) == 0)) { > > + WARN_ONCE(!fs, "request_module fs-%.*s succeeded, but still no fs?\n", len, name); > > The WARN needs to go below the second __get_fs_type() attempt, no? > Because we want to try __get_fs_type() again right after > request_module(), to see if the fs loaded, and _then_ WARN if it > doesn't appear to be loaded. Doh, yes, sorry will send v2. Luis
