linux-kernel - Re: BUG avc_node: Objects remaining on kmem_cache

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Date:	Thu, 17 Sep 2009 15:51:28 -0400
From:	Eric Paris <eparis@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	James Morris <jmorris@...ei.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Howells <dhowells@...hat.com>,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: BUG avc_node: Objects remaining on kmem_cache_close()

On Thu, 2009-09-17 at 18:21 +0200, Ingo Molnar wrote:
> * Eric Paris <eparis@...hat.com> wrote:
> 
> > On Thu, 2009-09-17 at 17:19 +0200, Ingo Molnar wrote:
> > > here's a new failure mode i havent seen before (possibly a variation of 
> > > the others):
> > > 
> > > [   20.036058] Freeing unused kernel memory: 1332k freed
> > > [   20.316099] SELinux:  Disabled at runtime.
> > > [   20.320059] =============================================================================
> > > [   20.324029] BUG avc_node: Objects remaining on kmem_cache_close()
> > > [   20.324029] -----------------------------------------------------------------------------
> > > [   20.324029] 
> > > [   20.324029] INFO: Slab 0xffffea0000de4230 objects=30 used=9 fp=0xffff88003f80a4c8 flags=0x4000000000000082
> > > [   20.324029] Pid: 1, comm: init Not tainted 2.6.31-tip-06326-g7ed9b83-dirty #14930
> > > [   20.324029] Call Trace:
> > > [   20.324029]  [<ffffffff810de4ba>] slab_err+0xb0/0xd2
> > > [   20.324029]  [<ffffffff810dfa58>] list_slab_objects+0xa8/0x14e
> > > [   20.324029]  [<ffffffff810e2d48>] kmem_cache_destroy+0x108/0x1d8
> > > [   20.324029]  [<ffffffff813c3e44>] avc_disable+0x37/0x4d
> > > [   20.324029]  [<ffffffff813ccf39>] selinux_disable+0x53/0xb5
> > > [   20.324029]  [<ffffffff813cd692>] sel_write_disable+0xa2/0x110
> > > [   20.324029]  [<ffffffff810e68c7>] vfs_write+0xc2/0x132
> > > [   20.324029]  [<ffffffff810e6a37>] sys_write+0x5b/0x98
> > > [   20.324029]  [<ffffffff810120af>] system_call_fastpath+0x16/0x1b
> > > [   20.324029] INFO: Object 0xffff88003f80a000 @offset=0
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=5072 cpu=0 pid=0
> > > [   20.324029] INFO: Object 0xffff88003f80a088 @offset=136
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=5055 cpu=0 pid=0
> > > [   20.324029] INFO: Object 0xffff88003f80a110 @offset=272
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=4981 cpu=0 pid=6
> > > [   20.324029] INFO: Object 0xffff88003f80a198 @offset=408
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=4229 cpu=0 pid=1
> > > [   20.324029] INFO: Object 0xffff88003f80a220 @offset=544
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=4215 cpu=0 pid=1
> > > [   20.324029] INFO: Object 0xffff88003f80a2a8 @offset=680
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=4215 cpu=0 pid=1
> > > [   20.324029] INFO: Object 0xffff88003f80a330 @offset=816
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=89 cpu=0 pid=1
> > > [   20.324029] INFO: Object 0xffff88003f80a3b8 @offset=952
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=57 cpu=0 pid=1
> > > [   20.324029] INFO: Object 0xffff88003f80a440 @offset=1088
> > > [   20.324029] INFO: Allocated in avc_alloc_node+0x36/0x195 age=48 cpu=0 pid=1
> > > [   20.324031] SLUB avc_node: kmem_cache_destroy called for cache that still has objects.
> > > [   20.328031] Pid: 1, comm: init Not tainted 2.6.31-tip-06326-g7ed9b83-dirty #14930
> > > [   20.332031] Call Trace:
> > > [   20.334489]  [<ffffffff810e2db7>] kmem_cache_destroy+0x177/0x1d8
> > > [   20.336032]  [<ffffffff813c3e44>] avc_disable+0x37/0x4d
> > > [   20.340033]  [<ffffffff813ccf39>] selinux_disable+0x53/0xb5
> > > [   20.344032]  [<ffffffff813cd692>] sel_write_disable+0xa2/0x110
> > > [   20.348032]  [<ffffffff810e68c7>] vfs_write+0xc2/0x132
> > > [   20.352032]  [<ffffffff810e6a37>] sys_write+0x5b/0x98
> > > [   20.356033]  [<ffffffff810120af>] system_call_fastpath+0x16/0x1b
> > > [   20.368209] SELinux:  Unregistering netfilter hooks
> > > [   20.372051] type=1404 audit(1253208317.372:2): selinux=0 auid=4294967295 ses=4294967295
> > 
> > Same thing as your last report.  I have a fix, but I can't seem to 
> > test it because of the bug report I sent you last night.  Chicken?  
> > Egg? (you can work around with selinux=0)
> 
> ah - got quite some backlog.
> 
> You said there:
> 
>  Bisect comes down to: 774a694f8cd08115d130a290d73c6d8563f26b1b
>  commit 774a694f8cd08115d130a290d73c6d8563f26b1b
>  Merge: 4f0ac85... e1f8450...
> 
> Could you please double check the bisection result again, i.e. that all 
> of these are true:

Sorry to be so slow to respond.

>  774a694: bad
Correct
>  4f0ac85: good
Correct.
>  e1f8450: good
Incorrect

Just a couple more cycles to get a better commit.  Not sure why the last
one stopped where it did.

-Eric

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