Re: [PATCH] block2mtd lockdep_init_map warning

Peter Zijlstra
2008-01-07T10:05:26Z

On Sun, 2008-01-06 at 14:11 -0500, Erez Zadok wrote:

> > Ingo, Peter, does either of you actually care about this problem? In
> > the last round when I debugged this problem there was a notable lack of
> > reaction from either of you.
>
> The problem appears to be an interaction of two components--module loading
> and lockdep--that's perhaps why it wasn't given enough attention.

Would something like this work for people?

Not-Yet-Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/include/linux/sched.h
@@ -1160,6 +1160,7 @@ struct task_struct {
int lockdep_depth;
struct held_lock held_locks[MAX_LOCK_DEPTH];
unsigned int lockdep_recursion;
+ struct module *loading_module;
#endif

/* journalling filesystem info */
Index: linux-2.6/kernel/module.c
===================================================================
--- linux-2.6.orig/kernel/module.c
+++ linux-2.6/kernel/module.c
@@ -2023,6 +2023,9 @@ static struct module *load_module(void _
printk(KERN_WARNING "%s: Ignoring obsolete parameters\n",
mod->name);

+#ifdef CONFIG_LOCKDEP
+ current->loading_module = mod;
+#endif
/* Size of section 0 is 0, so this works well if no params */
err = parse_args(mod->name, mod->args,
(struct kernel_param *)
@@ -2030,6 +2033,9 @@ static struct module *load_module(void _
sechdrs[setupindex].sh_size
/ sizeof(struct kernel_param),
NULL);
+#ifdef CONFIG_LOCKDEP
+ current->loading_module = NULL
+#endif
if (err < 0)
goto arch_cleanup;

@@ -2454,6 +2460,17 @@ int is_module_address(unsigned long addr
}
}

+#ifdef CONFIG_LOCKDEP
+ if (current->loading_module) {
+ mod = current->loading_module;
+ if (within(addr, mod->module_init, mod->init_text_size)
+ || within(addr, mod->module_core, mod->core_text_size)) {
+ preempt_enable();
+ return 1;
+ }
+ }
+#endif
+
preempt_enable();

return 0;