On Sun, May 24, 2020 at 02:57:27PM +0200, Greg Kroah-Hartman wrote: > On Sat, May 23, 2020 at 08:44:06AM -0700, Randy Dunlap wrote: > > On 5/23/20 8:36 AM, Greg Kroah-Hartman wrote: > > > On Wed, May 13, 2020 at 06:18:40PM +0300, Heikki Krogerus wrote: > > >> In the function kobject_cleanup(), kobject_del(kobj) is > > >> called before the kobj->release(). That makes it possible to > > >> release the parent of the kobject before the kobject itself. > > >> > > >> To fix that, adding function __kboject_del() that does > > >> everything that kobject_del() does except release the parent > > >> reference. kobject_cleanup() then calls __kobject_del() > > >> instead of kobject_del(), and separately decrements the > > >> reference count of the parent kobject after kobj->release() > > >> has been called. > > >> > > >> Reported-by: Naresh Kamboju <[email protected]> > > >> Reported-by: kernel test robot <[email protected]> > > >> Fixes: 7589238a8cf3 ("Revert "software node: Simplify > > >> software_node_release() function"") > > >> Suggested-by: "Rafael J. Wysocki" <[email protected]> > > >> Signed-off-by: Heikki Krogerus <[email protected]> > > >> Reviewed-by: Rafael J. Wysocki <[email protected]> > > >> Reviewed-by: Brendan Higgins <[email protected]> > > >> Tested-by: Brendan Higgins <[email protected]> > > >> Acked-by: Randy Dunlap <[email protected]> > > >> --- > > >> lib/kobject.c | 30 ++++++++++++++++++++---------- > > >> 1 file changed, 20 insertions(+), 10 deletions(-) > > > > > > Stepping back, now that it turns out this patch causes more problems > > > than it fixes, how is everyone reproducing the original crash here? > > > > Just load lib/test_printf.ko and boom! > > Thanks, that helps. > > Ok, in messing around with the kobject core more, originally we thought > this was an issue of the kobject uevent happening for the parent pointer > (when the parent was invalid). so, moving things around some more, and > now I'm crashing in software_node_release() when we are trying to access > swnode->parent->child_ids as parent is invalid there. > > So I feel like this is a swnode bug, or a use of swnode in a way it > shouldn't be that the testing framework is exposing somehow. > > Let me dig deeper...
Ah, ick, static software nodes trying to be cleaned up in the totally wrong order. You can't just try to randomly clean up a kobject anywhere in the middle of the hierarchy, that's flat out not going to work properly. let me unwind it... greg k-h
