linux-kernel - Re: V3.10-rc1 memory leak

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Date:	Tue, 14 May 2013 20:57:03 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Larry Finger <Larry.Finger@...inger.net>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: V3.10-rc1 memory leak

On Tue, 2013-05-14 at 17:20 -0400, Steven Rostedt wrote:
> On Tue, 2013-05-14 at 16:10 -0500, Larry Finger wrote:
> > On 05/14/2013 03:30 PM, Catalin Marinas wrote:
> > >
> > > I just got a patch today:
> > >
> > > https://lkml.org/lkml/2013/5/10/607
> > >
> > > which could be related. If Rusty doesn't push it I'll do. But please let
> > > me know if it does not solve the problem.
> > 
> > This patch fixes my problem. Now I can see the next new problem reported by 
> > kmemleak. :)
> > 
> > Thanks to you and Jianpeng Ma,
> > 
> > Larry
> > 
> 
> It goes away on my testing too. So you can add:
> 
> Tested-by: Steven Rostedt <rostedt@...dmis.org>
> 

But we are not out of the woods yet. I'm also getting these:

unreferenced object 0xffff88007800efc0 (size 32):
  comm "modprobe", pid 1309, jiffies 4294697214 (age 188.356s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 a8 d0 3e a0 ff ff ff ff  ..........>.....
    30 d1 3e a0 ff ff ff ff 00 00 00 00 00 00 00 00  0.>.............
  backtrace:
    [<ffffffff814b535f>] kmemleak_alloc+0x73/0x98
    [<ffffffff8112003c>] kmemleak_alloc_recursive.constprop.42+0x16/0x18
    [<ffffffff81120dfe>] kmem_cache_alloc_trace+0xc0/0x10b
    [<ffffffff810e5478>] jump_label_module_notify+0xce/0x1d5
    [<ffffffff814d221d>] notifier_call_chain+0x37/0x63
    [<ffffffff8105c29c>] __blocking_notifier_call_chain+0x4b/0x60
    [<ffffffff8105c2c5>] blocking_notifier_call_chain+0x14/0x16
    [<ffffffff8108fe83>] load_module+0x1d7f/0x20d3
    [<ffffffff810902b0>] SyS_init_module+0xd9/0xdb
    [<ffffffff814d5754>] tracesys+0xdd/0xe2
    [<ffffffffffffffff>] 0xffffffffffffffff

Where it points to the allocation in jump_label_add_module() where it
allocates the jlm. And this does get freed in jump_label_del_module(). I
put in printks in add_module():

	printk("alloc %p (%s)\n", jlm, mod->name);

and in del_module:

	printk("free %p (%s)\n", jlm, mod->name);

And got this:

[   29.917577] alloc ffff88007800efc0 (kvm_intel)


And removing kvm_intel, I got:

[  364.965916] free ffff88007800efc0 (kvm_intel)


Thus it seems to be yet another false positive :-(

-- Steve


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