From: Konstantin Khorenko <khorenko@virtuozzo.com>
To: Jessica Yu <jeyu@kernel.org>, Prarit Bhargava <prarit@redhat.com>,
Barret Rhoden <brho@google.com>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
linux-kernel@vger.kernel.org, David Arcari <darcari@redhat.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: [PATCH 1/1] kernel/module.c: wakeup processes in module_wq on module unload
Date: Wed, 13 Nov 2019 12:29:50 +0300 [thread overview]
Message-ID: <20191113092950.15556-2-khorenko@virtuozzo.com> (raw)
In-Reply-To: <20191113092950.15556-1-khorenko@virtuozzo.com>
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")
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
kernel/module.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/module.c b/kernel/module.c
index ff2d7359a418..cb09a5f37a5f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1033,6 +1033,8 @@ 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);
--
2.15.1
next prev parent reply other threads:[~2019-11-13 9:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-13 9:29 [PATCH 0/1] kernel/module.c: don't allow modprobe to hang forever on a module load Konstantin Khorenko
2019-11-13 9:29 ` Konstantin Khorenko [this message]
2019-11-13 13:51 ` [PATCH 1/1] kernel/module.c: wakeup processes in module_wq on module unload Prarit Bhargava
2019-11-15 10:28 ` Jessica Yu
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