On Sun, Apr 8, 2018 at 5:25 PM, Sasha Levin <alexander.le...@microsoft.com> wrote: > From: "Luis R. Rodriguez" <mcg...@kernel.org> > > [ Upstream commit 41124db869b7e00e12052555f8987867ac01d70c ] > > 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 <ru...@rustcorp.com.au> > Cc: Jessica Yu <j...@redhat.com> > Signed-off-by: Luis R. Rodriguez <mcg...@kernel.org> > Signed-off-by: Al Viro <v...@zeniv.linux.org.uk> > Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Acked-by: Luis R. Rodriguez <mcg...@kernel.org> The issue is real, and specially older kernels with older userspace can suffer with pain. It doesn't follow the typical stable candidate-fix, however, such simple check *can* help rule out tons of stupid debugging where the culprit really was userspace. Luis
