On Mon, 24 Mar 2014 20:26:05 +0900
Masami Hiramatsu <masami.hiramatsu...@hitachi.com> wrote:
> Thank you for reporting with this pretty backtrace :)
> Steven, I think this is not the kprobe bug but ftrace (and perhaps, module).
Looks to be more of a module issue than a ftrace issue.
>
> If the ftrace can set loading module text read only before the module
> subsystem
> expected, I think it should be protected by the module subsystem itself
> (e.g. set_all_modules_text_ro(rw) skips the modules which is
> MODULE_STATE_COMING)
>
Does this patch fix it?
In-review-off-by: Steven Rostedt <rost...@goodmis.org>
diff --git a/include/linux/module.h b/include/linux/module.h
index 5a50539..a1acabf 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -207,10 +207,11 @@ struct module_use {
};
enum module_state {
- MODULE_STATE_LIVE, /* Normal state. */
- MODULE_STATE_COMING, /* Full formed, running module_init. */
- MODULE_STATE_GOING, /* Going away. */
- MODULE_STATE_UNFORMED, /* Still setting it up. */
+ MODULE_STATE_LIVE, /* Normal state. */
+ MODULE_STATE_COMING, /* Full formed, running module_init. */
+ MODULE_STATE_COMING_FINAL, /* Ready to be changed to read only. */
+ MODULE_STATE_GOING, /* Going away. */
+ MODULE_STATE_UNFORMED, /* Still setting it up. */
};
/**
diff --git a/kernel/module.c b/kernel/module.c
index d24fcf2..0905bed 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1805,7 +1805,8 @@ void set_all_modules_text_ro(void)
mutex_lock(&module_mutex);
list_for_each_entry_rcu(mod, &modules, list) {
- if (mod->state == MODULE_STATE_UNFORMED)
+ if (mod->state == MODULE_STATE_UNFORMED ||
+ mod->state == MODULE_STATE_COMING)
continue;
if ((mod->module_core) && (mod->core_text_size)) {
set_page_attributes(mod->module_core,
@@ -3020,6 +3021,13 @@ static int do_init_module(struct module *mod)
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_COMING, mod);
+ /*
+ * This module must not be changed by set_all_modules_text_ro()
+ * until we get here. Otherwise notifiers that change text
+ * (like ftrace does) will break.
+ */
+ mod->state = MODULE_STATE_COMING_FINAL;
+
/* Set RO and NX regions for core */
set_section_ro_nx(mod->module_core,
mod->core_text_size,
--
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