On Fri, Jun 14, 2019 at 04:04:57PM +0200, Petr Mladek wrote: > On Thu 2019-06-13 20:07:23, Josh Poimboeuf wrote: > > External callers of the module page attribute change functions now need > > to have the text_mutex. Enforce that with lockdep assertions. > > > > diff --git a/kernel/module.c b/kernel/module.c > > index 6e6712b3aaf5..e43a90ee2d23 100644 > > --- a/kernel/module.c > > +++ b/kernel/module.c > > @@ -3519,7 +3534,7 @@ static noinline int do_init_module(struct module *mod) > > /* Switch to core kallsyms now init is done: kallsyms may be walking! */ > > rcu_assign_pointer(mod->kallsyms, &mod->core_kallsyms); > > #endif > > - module_enable_ro(mod, true); > > + __module_enable_ro(mod, true); > > This one must be called under text_mutex. Otherwise it might get > called when ftrace is in the middle of modifying the functions. > > It should be enough to take text_mutex right around this call. > It will prevent making the code ro when ftrace is doing > the modification. It safe also the other way. > set_all_modules_text_ro() does not call frob_ro_after_init(). > Therefore ftrace could not make the after_init section RO prematurely. > > > mod_tree_remove_init(mod); > > module_arch_freeing_init(mod); > > mod->init_layout.base = NULL; > > @@ -3626,8 +3641,8 @@ static int complete_formation(struct module *mod, > > struct load_info *info) > > /* This relies on module_mutex for list integrity. */ > > module_bug_finalize(info->hdr, info->sechdrs, mod); > > > > - module_enable_ro(mod, false); > > - module_enable_nx(mod); > > + __module_enable_ro(mod, false); > > + __module_enable_nx(mod); > > This one is OK. It is called when the module is in > MODULE_STATE_UNFORMED. Therefore it is ignored by ftrace. > The module state is manipulated and checked under module_mutex.
Yes, good catch. Thanks. -- Josh
