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

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Message-ID: <20130515164743.GD9324@arm.com>
Date:	Wed, 15 May 2013 17:47:43 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Toshi Kani <toshi.kani@...com>
Cc:	"rjw@...k.pl" <rjw@...k.pl>,
	Larry Finger <Larry.Finger@...inger.net>,
	Steven Rostedt <rostedt@...dmis.org>,
	"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>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: Re: V3.10-rc1 memory leak

On Wed, May 15, 2013 at 04:49:50PM +0100, Toshi Kani wrote:
> On Wed, 2013-05-15 at 16:02 +0100, Catalin Marinas wrote:
> > On Wed, May 15, 2013 at 04:15:46AM +0100, Larry Finger wrote:
> > > I do not see that particular one; however, I see 4 instances of
> > > 
> > > unreferenced object 0xffff8800b7979750 (size 8):
> > >    comm "swapper/0", pid 1, jiffies 4294892402 (age 21888.316s)
> > >    hex dump (first 8 bytes):
> > >      31 38 00 b7 00 88 ff ff                          18......
> > >    backtrace:
> > >      [<ffffffff81432ea1>] kmemleak_alloc+0x21/0x50
> > >      [<ffffffff81145d50>] __kmalloc_track_caller+0x140/0x2b0
> > >      [<ffffffff81119fb5>] kstrdup+0x35/0x70
> > >      [<ffffffff8125febc>] acpi_set_pnp_ids+0xd0/0x304
> > >      [<ffffffff81260c47>] acpi_scan_init_hotplug+0x47/0xa1
> > >      [<ffffffff81261223>] acpi_bus_check_add+0x66/0xd7
> > >      [<ffffffff8127877a>] acpi_ns_walk_namespace+0xb9/0x173
> > >      [<ffffffff81278bf3>] acpi_walk_namespace+0x93/0xc6
> > >      [<ffffffff812612dc>] acpi_bus_scan+0x48/0x9a
> > >      [<ffffffff818c983d>] acpi_scan_init+0x57/0x14b
> > >      [<ffffffff818c966a>] acpi_init+0x244/0x286
> > >      [<ffffffff810002fa>] do_one_initcall+0x10a/0x160
> > >      [<ffffffff8189cef0>] kernel_init_freeable+0x103/0x192
> > >      [<ffffffff814313a9>] kernel_init+0x9/0xf0
> > >      [<ffffffff8144992c>] ret_from_fork+0x7c/0xb0
> > >      [<ffffffffffffffff>] 0xffffffffffffffff
> > > 
> > > All four were allocated early in the bootup, and are the only leaks reported in 
> > > my system. I have not yet tested to see if they are false.
> > 
> > This looks to me like a real leak, possibly introduced by commit
> > 6b772e8f9 (ACPI: Update PNPID match handling for notify). The
> > acpi_scan_init_hotplug() function calls acpi_set_pnp_ids() which
> > allocates pnp.unique_id (kstrdup()) but for some reason it fails and
> > does not set pnp.type.hardware_id. The return does not call
> > acpi_free_pnp_ids() which would be responsible for such freeing.
> 
> I agree with your analysis.  It appears that this ACPI device object has
> _UID but not _HID.  ACPI spec defines that _UID is a unique ID among a
> same _HID.  So, it is odd to have _UID without _HID.  But, nonetheless,
> this case needs to be handled as such systems exist.
> 
> > Something like below, but not tested and may fail some NULL pointer
> > checks:
> 
> The change looks good.  acpi_free_pnp_ids() handles this empty list
> pnp->ids properly.  Are you going to submit this patch with your
> signed-off?

Yes, I'll post it shortly. But I'd like an acked/tested-by as I don't
have a platform to test it.

Thanks.

-- 
Catalin
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