Re: memleaks, acpi + ext4 + tty

From: Luis R. Rodriguez
Date: Mon Aug 31 2009 - 14:38:37 EST

On Mon, Aug 31, 2009 at 10:50 AM, Luis R. Rodriguez<mcgrof@xxxxxxxxx> wrote:
> On Mon, Aug 31, 2009 at 1:23 AM, Luis R. Rodriguez<mcgrof@xxxxxxxxx> wrote:
>> On Fri, Aug 28, 2009 at 3:09 PM, Luis R. Rodriguez<mcgrof@xxxxxxxxx> wrote:
>>> On Fri, Aug 28, 2009 at 2:50 PM, Luis R. Rodriguez<mcgrof@xxxxxxxxx> wrote:
>>>> On Fri, Aug 28, 2009 at 9:52 AM, Luis R. Rodriguez<mcgrof@xxxxxxxxx> wrote:
>>>>> On Fri, Aug 28, 2009 at 9:32 AM, Catalin Marinas<catalin.marinas@xxxxxxx> wrote:
>>>>>> "Luis R. Rodriguez" <mcgrof@xxxxxxxxx> wrote:
>>>>>>> I have an assorted collection of kmemleak reports for acpi, ext4 and
>>>>>>> tty, not sure how to read these yet to fix so figure I'd at least post
>>>>>>> them. To reproduce I can just dd=/dev/zero to some big file and played
>>>>>>> some video.
>>>>>> If you do a few echo scan > /sys/kernel/debug/kmemleak, do they
>>>>>> disappear (i.e. transient false positives)?
>>>>> Sure, I will once on rc8.
>>>>>> Which kernel version is this?
>>>>> v2.6.31-rc7-33172-gf4a9f9a
>>>>> This is from wireless-testing, which has wireless patches on top of
>>>>> rc7. John just rebased to rc8 so will give that a shot at work.
>>>>>>> unreferenced object 0xffff88003e0015c0 (size 64):
>>>>>>> Â comm "swapper", pid 1, jiffies 4294892352
>>>>>>> Â backtrace:
>>>>>>> Â Â [<ffffffff81121fad>] create_object+0x13d/0x2d0
>>>>>>> Â Â [<ffffffff81122265>] kmemleak_alloc+0x25/0x60
>>>>>>> Â Â [<ffffffff81118a03>] kmem_cache_alloc_node+0x193/0x200
>>>>>>> Â Â [<ffffffff8152509e>] process_zones+0x70/0x1cd
>>>>>>> Â Â [<ffffffff81525230>] pageset_cpuup_callback+0x35/0x92
>>>>>>> Â Â [<ffffffff8152c9b7>] notifier_call_chain+0x47/0x90
>>>>>>> Â Â [<ffffffff81078549>] __raw_notifier_call_chain+0x9/0x10
>>>>>>> Â Â [<ffffffff81523f25>] _cpu_up+0x75/0x130
>>>>>>> Â Â [<ffffffff8152403a>] cpu_up+0x5a/0x6a
>>>>>>> Â Â [<ffffffff8181969e>] kernel_init+0xcc/0x1ba
>>>>>>> Â Â [<ffffffff810130ca>] child_rip+0xa/0x20
>>>>>>> Â Â [<ffffffffffffffff>] 0xffffffffffffffff
>>>>>> Can't really tell. Maybe a false positive caused by kmemleak not
>>>>>> scanning the pgdata node_zones. Can you post your .config file?
>>>>> Sure, attached.
>>>>>>> unreferenced object 0xffff88003cb5f700 (size 64):
>>>>>>> Â comm "swapper", pid 1, jiffies 4294892459
>>>>>>> Â backtrace:
>>>>>>> Â Â [<ffffffff81121fad>] create_object+0x13d/0x2d0
>>>>>>> Â Â [<ffffffff81122265>] kmemleak_alloc+0x25/0x60
>>>>>>> Â Â [<ffffffff81119f3b>] __kmalloc+0x16b/0x250
>>>>>>> Â Â [<ffffffff812bb549>] kzalloc+0xf/0x11
>>>>>>> Â Â [<ffffffff812bbb53>] acpi_add_single_object+0x58e/0xd3c
>>>>>>> Â Â [<ffffffff812bc51c>] acpi_bus_scan+0x125/0x1af
>>>>>>> Â Â [<ffffffff81842361>] acpi_scan_init+0xc8/0xe9
>>>>>>> Â Â [<ffffffff8184211c>] acpi_init+0x21f/0x265
>>>>>>> Â Â [<ffffffff8100a05b>] do_one_initcall+0x4b/0x1b0
>>>>>>> Â Â [<ffffffff81819736>] kernel_init+0x164/0x1ba
>>>>>>> Â Â [<ffffffff810130ca>] child_rip+0xa/0x20
>>>>>>> Â Â [<ffffffffffffffff>] 0xffffffffffffffff
>>>>>> I get ACPI reports as well and they may be real leaks. However, I
>>>>>> didn't have time to analyse the code (pretty complicated reference
>>>>>> counting).
>>>>> Heh OK thanks for reviewing them though.
>>>>>>> unreferenced object 0xffff880039571800 (size 1024):
>>>>>>> Â comm "exe", pid 1168, jiffies 4294893410
>>>>>>> Â backtrace:
>>>>>>> Â Â [<ffffffff81121fad>] create_object+0x13d/0x2d0
>>>>>>> Â Â [<ffffffff81122265>] kmemleak_alloc+0x25/0x60
>>>>>>> Â Â [<ffffffff81119f3b>] __kmalloc+0x16b/0x250
>>>>>>> Â Â [<ffffffff811e1d71>] ext4_mb_init+0x1a1/0x590
>>>>>>> Â Â [<ffffffff811d2da3>] ext4_fill_super+0x1df3/0x26c0
>>>>>>> Â Â [<ffffffff8112774f>] get_sb_bdev+0x16f/0x1b0
>>>>>>> Â Â [<ffffffff811c8fd3>] ext4_get_sb+0x13/0x20
>>>>>>> Â Â [<ffffffff81127216>] vfs_kern_mount+0x76/0x180
>>>>>>> Â Â [<ffffffff8112738d>] do_kern_mount+0x4d/0x130
>>>>>>> Â Â [<ffffffff8113fc57>] do_mount+0x307/0x8b0
>>>>>>> Â Â [<ffffffff8114028f>] sys_mount+0x8f/0xe0
>>>>>>> Â Â [<ffffffff81011f02>] system_call_fastpath+0x16/0x1b
>>>>>>> Â Â [<ffffffffffffffff>] 0xffffffffffffffff
>>>>>> The ext4 reports are real leaks and patch was posted here -
>>>>>> However, it hasn't been merged into
>>>>>> mainline yet (I cc'ed Aneesh).
>>>>>> The patch is merged in my "kmemleak-fixes" branch on
>>>>>> git://
>>>>> Will try to suck them out and try them.
>>>> OK -- tested rc8 + a pull of your tree into mine. The bootup was
>>>> really slow and something was just not going right. After a while
>>>> memleak complained it had 8 kmemleak logs but I was not able to get my
>>>> system usable enough to cat the file.
>>>> In cases like these I wish I would hookup my ctrl-alt-del to kexec() a
>>>> safe kernel.
>>>> After a long period of time it seems X wished it would start, it tried
>>>> and then flashed back to the tty. This kept repeating in a loop.
>>>> I am not sure if the culprit was rc8 or the kmemleak branch merge --
>>>> I'll find out after I boot into rc8 in a few.
>>> rc8 busted my bootup, the issues are present with just
>>> wireless-testing. I highly doubt the issues are wireless-testing
>>> related so I will not bisect there. Since I am unable to get anything
>>> useful from the kernel to determine what may have gone sour, any
>>> suggestions on a path to bisect, or should I just do the whole tree?
>> I tried 2.6.31-rc8 from hpa's linux-2.6-allstable.git tree instead of
>> Linus [1] as I already had that tree, git describe says:
>> v2.6.31-rc8-15-gadda766
>> Testing this would be the same as testing Linus' blessed rc8 --
>> correct me I'm wrong. Contrary to what I expected this tree with the
>> same config works well!
>> I have compiled a fresh checkout of wireless-testing origin/master to
>> double check the issue and it is indeed only present on
>> wireless-testing. A diff stat between John's merge of 2.6.31-rc8 and
>> current master branch on wireless-testing [2] doesn't reveal much
>> other than wireless specific stuff, as expected, so it seems this may
>> after all be introduced in a recent patches in wireless-testing. I
>> still find this a bit odd given I see no others reporting major
>> issues. My boot doesn't go very far, it stalls for a while after input
>> devices are being detected, then it spits out a kmemleak warning about
>> 13 kmemleaks. Here's a picture [3]. I didn't bother waiting as I did
>> last time for X to try to come up, something is really wrong. I'll
>> bisect wireless-testing in the morning, starting with a good marker at
>> merge-2009-08-28 as that is when John pulled 2.6.31-rc8 (and I confirm
>> a diff stat between that and v2.6.31-rc8 yields nothing as it should)
>> and current master as the bad marker. I have 9 steps to go, will leave
>> first step compiling overnight.
>> [1] git://
>> [2] git diff --stat merge-2009-08-28..HEAD
>> [3]
>> [4] git diff --stat merge-2009-08-28..v2.6.31-rc8
> Hah, well this makes no sense:
> mcgrof@tux ~/wireless-testing (git::(no branch))$ git bisect bad
> a4e774ca75e5f2d8347b4d9746a2e0a9a4fc521b is first bad commit
> commit a4e774ca75e5f2d8347b4d9746a2e0a9a4fc521b
> Author: John W. Linville <linville@xxxxxxxxxxxxx>
> Date: Â Wed Feb 27 16:04:18 2008 -0500
> Â ÂAdd localversion-wireless to identify builds from this tree.
> Â ÂSigned-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
> :000000 100644 0000000000000000000000000000000000000000
> 6a05d60db3b21d9c0a0b93b831c6ea453dc98785 A Â Â Âlocalversion-wireless
> I'll try a fresh branch on merge-2009-08-28 ..

OK I tried this, I even 'rm -rf * ; git checkout -f' and ..
merge-2009-08-28 tag yields the same issues, long lag upon bootup with
some kmemleaks I cannot even get to check. So somehow something is
different between merge-2009-08-28 and Linus' rc8. This is just
bizarre so to be even safer I'm just going to do a fresh git clone on

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