| Message ID | 20170601180801.19827-1-mcgrof@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 01, 2017 at 11:08:01AM -0700, Luis R. Rodriguez wrote: > 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@rustcorp.com.au> > Cc: Jessica Yu <jeyu@redhat.com> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> *poke* Al? Luis
On Tue, Jun 20, 2017 at 10:57:46PM +0200, Luis R. Rodriguez wrote: > On Thu, Jun 01, 2017 at 11:08:01AM -0700, Luis R. Rodriguez wrote: > > 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@rustcorp.com.au> > > Cc: Jessica Yu <jeyu@redhat.com> > > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> > > *poke* Al? Will bounce to the default tree maintainer, Andrew :) Luis
diff --git a/fs/filesystems.c b/fs/filesystems.c index cac75547d35c..8b99955e3504 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)) { fs = __get_fs_type(name, len); + WARN_ONCE(!fs, "request_module fs-%.*s succeeded, but still no fs?\n", len, name); + } if (dot && fs && !(fs->fs_flags & FS_HAS_SUBTYPE)) { put_filesystem(fs);
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@rustcorp.com.au> Cc: Jessica Yu <jeyu@redhat.com> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> --- This v2 addresses the ordering issue Jessica pointed out. fs/filesystems.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)