blob: 15b40ed984dd25dc6977985497f0c1d45574d7f0 [file] [log] [blame]
From de9c079add80774d5aed368d85827fd7553c978c Mon Sep 17 00:00:00 2001
From: Konstantin Khorenko <khorenko@virtuozzo.com>
Date: Wed, 13 Nov 2019 12:29:50 +0300
Subject: [PATCH] kernel/module.c: wakeup processes in module_wq on module
unload
commit 5d603311615f612320bb77bd2a82553ef1ced5b7 upstream.
Fix the race between load and unload a kernel module.
sys_delete_module()
try_stop_module()
mod->state = _GOING
add_unformed_module()
old = find_module_all()
(old->state == _GOING =>
wait_event_interruptible())
During pre-condition
finished_loading() rets 0
schedule()
(never gets waken up later)
free_module()
mod->state = _UNFORMED
list_del_rcu(&mod->list)
(dels mod from "modules" list)
return
The race above leads to modprobe hanging forever on loading
a module.
Error paths on loading module call wake_up_all(&module_wq) after
freeing module, so let's do the same on straight module unload.
Fixes: 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading")
Reviewed-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/kernel/module.c b/kernel/module.c
index dcf2cc656e7c..b11d200aebbd 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1019,6 +1019,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
free_module(mod);
+ /* someone could wait for the module in add_unformed_module() */
+ wake_up_all(&module_wq);
return 0;
out:
mutex_unlock(&module_mutex);
--
2.7.4