Commit 161b6ae0 authored May 28, 2011 by Marcin Slusarz Committed by Thomas Gleixner Jun 20, 2011

debugobjects: Fix boot crash when kmemleak and debugobjects enabled



Order of initialization look like this:
...
debugobjects
kmemleak
...(lots of other subsystems)...
workqueues (through early initcall)
...

debugobjects use schedule_work for batch freeing of its data and kmemleak
heavily use debugobjects, so when it comes to freeing and workqueues were
not initialized yet, kernel crashes:

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff810854d1>] __queue_work+0x29/0x41a
 [<ffffffff81085910>] queue_work_on+0x16/0x1d
 [<ffffffff81085abc>] queue_work+0x29/0x55
 [<ffffffff81085afb>] schedule_work+0x13/0x15
 [<ffffffff81242de1>] free_object+0x90/0x95
 [<ffffffff81242f6d>] debug_check_no_obj_freed+0x187/0x1d3
 [<ffffffff814b6504>] ? _raw_spin_unlock_irqrestore+0x30/0x4d
 [<ffffffff8110bd14>] ? free_object_rcu+0x68/0x6d
 [<ffffffff8110890c>] kmem_cache_free+0x64/0x12c
 [<ffffffff8110bd14>] free_object_rcu+0x68/0x6d
 [<ffffffff810b58bc>] __rcu_process_callbacks+0x1b6/0x2d9
...

because system_wq is NULL.

Fix it by checking if workqueues susbystem was initialized before using.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/20110528112342.GA3068@joi.lan


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent f8b7fc6b

lib/debugobjects.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -198,7 +198,7 @@ static void free_object(struct debug_obj *obj)
		* initialized:
		*/
		if (obj_pool_free > ODEBUG_POOL_SIZE && obj_cache)
		sched = !work_pending(&debug_obj_work);
		sched = keventd_up() && !work_pending(&debug_obj_work);
		hlist_add_head(&obj->node, &obj_pool);
		obj_pool_free++;
		obj_pool_used--;

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