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From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, oleg@redhat.com, torvalds@linux-foundation.org
Cc: tglx@linutronix.de, ilya.dryomov@inktank.com,
	umgwanakikbuti@gmail.com, linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Fengguang Wu <fengguang.wu@intel.com>
Subject: [PATCH 08/11] module: Fix nested sleep
Date: Wed, 24 Sep 2014 10:18:53 +0200
Message-ID: <20140924082242.458562904@infradead.org> (raw)
In-Reply-To: <20140924081845.572814794@infradead.org>

[-- Attachment #0: peterz-sleep-module.patch --]
[-- Type: text/plain, Size: 1661 bytes --]

A genuine bug, we cannot use blocking primitives inside a wait loop.

So rewrite the wait_event_interruptible() usage to use the fresh
wait_woken() stuff.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/module.c |   30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3095,6 +3095,32 @@ static int may_init_module(void)
 }
 
 /*
+ * Can't use wait_event_interruptible() because our condition
+ * 'finished_loading()' contains a blocking primitive itself (mutex_lock).
+ */
+static int wait_finished_loading(struct module *mod)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	int ret = 0;
+
+	add_wait_queue(&module_wq, &wait);
+	for (;;) {
+		if (finished_loading(mod->name))
+			break;
+
+		if (signal_pending_state(TASK_INTERRUPTIBLE, current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+
+		wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+	}
+	remove_wait_queue(&module_wq, &wait);
+
+	return ret;
+}
+
+/*
  * We try to place it in the list now to make sure it's unique before
  * we dedicate too many resources.  In particular, temporary percpu
  * memory exhaustion.
@@ -3114,8 +3140,8 @@ static int add_unformed_module(struct mo
 		    || old->state == MODULE_STATE_UNFORMED) {
 			/* Wait in case it fails to load. */
 			mutex_unlock(&module_mutex);
-			err = wait_event_interruptible(module_wq,
-					       finished_loading(mod->name));
+
+			err = wait_finished_loading(mod);
 			if (err)
 				goto out_unlocked;
 			goto again;



  parent reply index

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-24  8:18 [PATCH 00/11] nested sleeps, fixes and debug infrastructure Peter Zijlstra
2014-09-24  8:18 ` [PATCH 01/11] locking/mutex: Dont assume TASK_RUNNING Peter Zijlstra
2014-10-28 11:09   ` [tip:sched/core] locking/mutex: Don't " tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 02/11] wait: Provide infrastructure to deal with nested blocking Peter Zijlstra
2014-09-29 21:02   ` Oleg Nesterov
2014-10-02  7:37     ` Peter Zijlstra
2014-10-02 21:21       ` Oleg Nesterov
2014-10-28 11:09   ` [tip:sched/core] sched/wait: " tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 03/11] wait: Add might_sleep() Peter Zijlstra
2014-10-28 11:09   ` [tip:sched/core] sched/wait: Add might_sleep() checks tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 04/11] exit: Deal with nested sleeps Peter Zijlstra
2014-10-28 11:10   ` [tip:sched/core] sched, " tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 05/11] inotify: " Peter Zijlstra
2014-10-28 11:10   ` [tip:sched/core] sched, " tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 06/11] tty: " Peter Zijlstra
2014-10-28 11:10   ` [tip:sched/core] sched, " tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 07/11] smp: Correctly deal " Peter Zijlstra
2014-10-28 11:11   ` [tip:sched/core] sched, " tip-bot for Peter Zijlstra
2014-09-24  8:18 ` Peter Zijlstra [this message]
2014-09-29 22:18   ` [PATCH 08/11] module: Fix nested sleep Oleg Nesterov
2014-09-30 13:43     ` Peter Zijlstra
2014-10-28 11:11   ` [tip:sched/core] sched, modules: Fix nested sleep in add_unformed_module() tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 09/11] net: Clean up sk_wait_event() vs might_sleep() Peter Zijlstra
2014-09-24  8:36   ` Peter Zijlstra
2014-10-28 11:11   ` [tip:sched/core] sched, net: Clean up sk_wait_event() vs. might_sleep() tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 10/11] sched: Debug nested sleeps Peter Zijlstra
2014-09-29 22:13   ` Oleg Nesterov
2014-09-30 13:49     ` Peter Zijlstra
2014-09-30 21:47       ` Oleg Nesterov
2014-10-01 16:10         ` Peter Zijlstra
2014-10-01 18:35           ` Oleg Nesterov
2014-10-02  9:07             ` Peter Zijlstra
2014-10-02 21:34               ` Oleg Nesterov
2014-10-28 11:11   ` [tip:sched/core] " tip-bot for Peter Zijlstra
2014-09-24  8:18 ` [PATCH 11/11] sched: Exclude cond_resched() from nested sleep test Peter Zijlstra
2014-10-28 11:12   ` [tip:sched/core] " tip-bot for Peter Zijlstra
2014-09-25  8:30 ` [PATCH 00/11] nested sleeps, fixes and debug infrastructure Mike Galbraith
2014-09-25  9:06   ` Peter Zijlstra
2014-09-25  9:10     ` Mike Galbraith
2014-09-25  9:15     ` Peter Zijlstra
2014-09-25  9:56       ` Mike Galbraith
2014-09-25 13:59         ` BUG: sleeping function called from invalid context at drivers/cpufreq/cpufreq.c:370 Mike Galbraith
2014-09-26  6:24           ` Mike Galbraith
2014-09-26  7:54             ` Mike Galbraith
2014-09-26 14:10               ` Rafael J. Wysocki
2014-09-26 22:44               ` Rafael J. Wysocki
2014-09-27  6:14                 ` Mike Galbraith
2014-09-27 19:57                   ` Rafael J. Wysocki
2014-10-02 10:22       ` [PATCH 00/11] nested sleeps, fixes and debug infrastructure Peter Zijlstra
2014-10-02 12:15         ` Peter Zijlstra
2014-10-27 13:41           ` Peter Zijlstra
2014-10-28  0:07             ` Oleg Nesterov
2014-10-28  8:23               ` Peter Zijlstra
2014-10-29  0:00                 ` Oleg Nesterov
2014-10-29  9:35                   ` Peter Zijlstra
2014-10-29 11:31                     ` Peter Zijlstra
2014-10-29 11:36                       ` Peter Zijlstra
2014-10-29 14:26                   ` Peter Zijlstra
2014-11-04 16:08         ` [tip:sched/core] audit, sched/wait: Fixup kauditd_thread() wait loop tip-bot for Peter Zijlstra

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