linux-kernel - Re: kmemleak: unreferenced object in copy

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Date:	Wed, 30 Nov 2011 11:54:59 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	"Wouter M. Koolen" <W.M.Koolen-Wijkstra@....nl>
Cc:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	x86@...nel.org
Subject: Re: kmemleak: unreferenced object in copy_thread

On 28 November 2011 18:09, Wouter M. Koolen <W.M.Koolen-Wijkstra@....nl> wrote:
> Dear kmemleak and/or x86 maintainers,
>
> I asked for too much memory. The machine started swapping. I killed the hog.
> Then I found this gem:
>
> unreferenced object 0xffff8800006ea000 (size 8192):
>  comm "Xorg", pid 1415, jiffies 4298164697 (age 2433.696s)
>  hex dump (first 32 bytes):
>    00 00 00 00 00 00 00 00 0f 00 00 00 0f 00 00 00  ................
>    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  backtrace:
>    [<ffffffff813feeb1>] kmemleak_alloc+0x21/0x50
>    [<ffffffff8111086b>] kmem_cache_alloc_trace+0xdb/0x1d0
>    [<ffffffff81001fbe>] copy_thread+0x1be/0x260
>    [<ffffffff81044953>] copy_process+0xee3/0x1520
>    [<ffffffff810450d6>] do_fork+0x116/0x350
>    [<ffffffff8100a7d3>] sys_clone+0x23/0x30
>    [<ffffffff8141c173>] stub_clone+0x13/0x20
>    [<ffffffffffffffff>] 0xffffffffffffffff

I can't yet tell whether it's a false positive or not. Did the X
server die? Is the process with pid 1415 still around? The leaked
object looks like the thread stack (8K) and it should have been
removed when the corresponding process was killed.

-- 
Catalin
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