On 14.11.22 16:38, Luis Chamberlain wrote:
On Mon, Nov 14, 2022 at 09:57:56AM +0100, David Hildenbrand wrote:
On 12.11.22 02:47, Luis Chamberlain wrote:
On Wed, Oct 19, 2022 at 02:00:55PM +0200, Petr Pavlu wrote:
On 10/18/22 20:33, Luis Chamberlain wrote:
On Sat, Oct 15, 2022 at 11:27:10AM +0200, Petr Pavlu wrote:
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.
The first two hunks are a revert of commit 6e6de3dee51a and I'm under
the impression that cauased your issues as *more* modules states are
allowed through.
The last hunk tries to fix what 6e6de3dee51a wanted to do.
Note that I don't think the issue I raised is due to 6e6de3dee51a.
But maybe I am missing something important.
Please do test if you can.
I don't have the machine at hand right now. But, again, I doubt this
will fix it.
The flow is in load_module():
mod = layout_and_allocate(info, flags);
if (IS_ERR(mod)) {
...
}
audit_log_kern_module(mod->name);
/* Reserve our place in the list. */
err = add_unformed_module(mod);
if (err)
goto free_module;
You can have 400 threads in layout_and_allocate() loading the same
module at the same time and running out of module space. Any changes to
add_unformed_module() and finished_loading() won't change that, because
they are not involved before the module space allocations happened.
--
Thanks,
David / dhildenb
