From: Konstantin Khorenko khorenko@virtuozzo.com
[ Upstream commit 5d603311615f612320bb77bd2a82553ef1ced5b7 ]
Fix the race between load and unload a kernel module.
sys_delete_module() try_stop_module() mod->state = _GOING add_unformed_module() old = find_module_all() (old->state == _GOING => wait_event_interruptible())
During pre-condition finished_loading() rets 0 schedule() (never gets waken up later) free_module() mod->state = _UNFORMED list_del_rcu(&mod->list) (dels mod from "modules" list)
return
The race above leads to modprobe hanging forever on loading a module.
Error paths on loading module call wake_up_all(&module_wq) after freeing module, so let's do the same on straight module unload.
Fixes: 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading") Reviewed-by: Prarit Bhargava prarit@redhat.com Signed-off-by: Konstantin Khorenko khorenko@virtuozzo.com Signed-off-by: Jessica Yu jeyu@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/module.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/kernel/module.c +++ b/kernel/module.c @@ -1014,6 +1014,8 @@ SYSCALL_DEFINE2(delete_module, const cha strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
free_module(mod); + /* someone could wait for the module in add_unformed_module() */ + wake_up_all(&module_wq); return 0; out: mutex_unlock(&module_mutex);