On 12.11.22 02:47, Luis Chamberlain wrote:

On Wed, Oct 19, 2022 at 02:00:55PM +0200, Petr Pavlu wrote:

quoted

On 10/18/22 20:33, Luis Chamberlain wrote:

quoted

On Sat, Oct 15, 2022 at 11:27:10AM +0200, Petr Pavlu wrote:

quoted

The patch does address a regression observed after commit 6e6de3dee51a
("kernel/module.c: Only return -EEXIST for modules that have finished
loading"). I guess it can have a Fixes tag added to the patch.

I think it is hard to split this patch into parts because the implemented
"optimization" is the fix.

git describe --contains 6e6de3dee51a
v5.3-rc1~38^2~6

I'm a bit torn about this situation. Reverting 6e6de3dee51a would be the
right thing to do, but without it, it still leaves the issue reported
by Prarit Bhargava. We need a way to resolve the issue on stable and
then your optimizations can be applied on top.

Simpler could be to do the following:

diff --git a/kernel/module/main.c b/kernel/module/main.c
index d02d39c7174e..0302ac387e93 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c

@@ -2386,7 +2386,8 @@ static bool finished_loading(const char *name)
  	sched_annotate_sleep();
  	mutex_lock(&module_mutex);
  	mod = find_module_all(name, strlen(name), true);
-	ret = !mod || mod->state == MODULE_STATE_LIVE;
+	ret = !mod || mod->state == MODULE_STATE_LIVE
+		|| mod->state == MODULE_STATE_GOING;
  	mutex_unlock(&module_mutex);
  
  	return ret;

@@ -2566,7 +2567,8 @@ static int add_unformed_module(struct module *mod)
  	mutex_lock(&module_mutex);
  	old = find_module_all(mod->name, strlen(mod->name), true);
  	if (old != NULL) {
-		if (old->state != MODULE_STATE_LIVE) {
+		if (old->state == MODULE_STATE_COMING
+		    || old->state == MODULE_STATE_UNFORMED) {
  			/* Wait in case it fails to load. */
  			mutex_unlock(&module_mutex);
  			err = wait_event_interruptible(module_wq,

@@ -2575,7 +2577,7 @@ static int add_unformed_module(struct module *mod)
  				goto out_unlocked;
  			goto again;
  		}
-		err = -EEXIST;
+		err = old->state != MODULE_STATE_LIVE ? -EBUSY : -EEXIST;
  		goto out;
  	}
  	mod_update_bounds(mod);

Prarit, can you verify this still does not break the issue you reported?
David, does this also fix your issue?

I didn't try, but from a quick glimpse I assume no. Allocating module 
space happens before handling eventual duplicates right now, before a 
module even is "alive" and in the MODULE_STATE_UNFORMED state.

But maybe I am missing something important.

-- 
Thanks,

David / dhildenb