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    SubjectRe: ftrace/kprobes: Warning when insmod two modules
    On Mon, 24 Mar 2014 20:26:05 +0900
    Masami Hiramatsu <masami.hiramatsu.pt@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 <rostedt@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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