Messages in this thread | | | Date | Wed, 26 Oct 2016 08:09:14 -0400 | From | Steven Rostedt <> | Subject | Re: [RFC PATCH 2/2] module: When modifying a module's text ignore modules which are going away too |
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On Wed, 26 Oct 2016 11:35:18 +1030 Rusty Russell <rusty@rustcorp.com.au> wrote:
> Aaron Tomlin <atomlin@redhat.com> writes: > > By default, during the access permission modification of a module's core > > and init pages, we only ignore modules that are malformed. There is no > > reason not to extend this to modules which are going away too. > > Well, it depends on all the callers (ie. ftrace): is that also ignoring > modules which are going away? > > Otherwise, we set MODULE_STATE_GOING, ftrace walks all the modules and > this one is still RO... >
Actually, looking into this more, you are correct. There's a possibility in enabling ftrace after the module is about to go but before ftrace_release_mod() is called (which will remove the module text from the ftrace function list).
I don't see any reason for not allowing set_all_modules_text_rw() from being called if a module is going. If a module is going, shouldn't its text be rw anyway?
Perhaps just preventing it from turning into ro will be sufficient. And remove the check from set_all_modules_text_rw().
-- Steve
> Thanks, > Rusty. > > > This patch makes both set_all_modules_text_rw() and > > set_all_modules_text_ro() skip modules which are going away too. > > > > Signed-off-by: Aaron Tomlin <atomlin@redhat.com> > > --- > > kernel/module.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/module.c b/kernel/module.c > > index ff93ab8..09c386b 100644 > > --- a/kernel/module.c > > +++ b/kernel/module.c > > @@ -1953,7 +1953,8 @@ void set_all_modules_text_rw(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_GOING) > > continue; > > > > frob_text(&mod->core_layout, set_memory_rw); > > @@ -1969,7 +1970,8 @@ 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_GOING) > > continue; > > > > frob_text(&mod->core_layout, set_memory_ro); > > -- > > 2.5.5
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