linux-kernel - Re: WARNING: at lib/debugobjects.c:262 debug_print

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Message-ID: <4F20160F.4020808@panasas.com>
Date:	Wed, 25 Jan 2012 16:47:43 +0200
From:	Boaz Harrosh <bharrosh@...asas.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Jeff Layton <jlayton@...hat.com>,
	Stanislaw Gruszka <sgruszka@...hat.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	<linux-kernel@...r.kernel.org>, <bfields@...hat.com>,
	<linux-nfs@...r.kernel.org>, Tejun Heo <tj@...nel.org>
Subject: Re: WARNING: at lib/debugobjects.c:262 debug_print_object+0x8c/0xb0()

On 01/25/2012 04:05 PM, Thomas Gleixner wrote:
> On Tue, 24 Jan 2012, Jeff Layton wrote:
>>> Still, I wonder if there are other problems like this around. The slab
>>> allocators seem to call debug_check_no_obj_freed() on kmem_cache_free,
>>> but parts of the objects themselves (like the timer in the work object
>>> here) get initialized in other places and aren't necessarily
>>> reinitialized when they're recycled out of the slab...
>>>
>>
>> On second thought...getting rid of the ctor function here might be
>> problematic. We have to call inode_init_once, etc...
>>
>> Almost all of the inode slabs have one, so I've settled for just moving
>> the INIT_DELAYED_WORK call out of init_once and into rpc_alloc_inode. I
>> sent a patch to Trond and linux-nfs to do that. That will fix this
>> case, but I do wonder if there are other places in the kernel that have
>> similar problems with debugobject initialization.
> 
> The problem is that debugobject requires that a newly allocated object
> is reinitialized and made available to the debugobjects code again
> simply because we remove it from the debugobjects core on
> kmem_cache_free(). 
> 
> The real question is why the heck kmem_cache_alloc() does not call the
> ctor on each allocation and just expects the previously used and freed
> object to be in a consistent initialiazed state.
> 

Perhaps it's some flags that is to do with the RCU delete thing.
You know for the lockless walks and stuff

> Thanks,
> 
> 	tglx

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