Re: memleaks, acpi + ext4 + tty

Luis R. Rodriguez
2009-08-28T21:50:29Z

On Fri, Aug 28, 2009 at 9:52 AM, Luis R. Rodriguez<mcgrof@gmail.com> wrote:
> On Fri, Aug 28, 2009 at 9:32 AM, Catalin Marinas<catalin.marinas@arm.com> wrote:
>> "Luis R. Rodriguez" <mcgrof@gmail.com> 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):
>>>   comm "swapper", pid 1, jiffies 4294892352
>>>   backtrace:
>>>     [<ffffffff81121fad>] create_object+0x13d/0x2d0
>>>     [<ffffffff81122265>] kmemleak_alloc+0x25/0x60
>>>     [<ffffffff81118a03>] kmem_cache_alloc_node+0x193/0x200
>>>     [<ffffffff8152509e>] process_zones+0x70/0x1cd
>>>     [<ffffffff81525230>] pageset_cpuup_callback+0x35/0x92
>>>     [<ffffffff8152c9b7>] notifier_call_chain+0x47/0x90
>>>     [<ffffffff81078549>] __raw_notifier_call_chain+0x9/0x10
>>>     [<ffffffff81523f25>] _cpu_up+0x75/0x130
>>>     [<ffffffff8152403a>] cpu_up+0x5a/0x6a
>>>     [<ffffffff8181969e>] kernel_init+0xcc/0x1ba
>>>     [<ffffffff810130ca>] child_rip+0xa/0x20
>>>     [<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):
>>>   comm "swapper", pid 1, jiffies 4294892459
>>>   backtrace:
>>>     [<ffffffff81121fad>] create_object+0x13d/0x2d0
>>>     [<ffffffff81122265>] kmemleak_alloc+0x25/0x60
>>>     [<ffffffff81119f3b>] __kmalloc+0x16b/0x250
>>>     [<ffffffff812bb549>] kzalloc+0xf/0x11
>>>     [<ffffffff812bbb53>] acpi_add_single_object+0x58e/0xd3c
>>>     [<ffffffff812bc51c>] acpi_bus_scan+0x125/0x1af
>>>     [<ffffffff81842361>] acpi_scan_init+0xc8/0xe9
>>>     [<ffffffff8184211c>] acpi_init+0x21f/0x265
>>>     [<ffffffff8100a05b>] do_one_initcall+0x4b/0x1b0
>>>     [<ffffffff81819736>] kernel_init+0x164/0x1ba
>>>     [<ffffffff810130ca>] child_rip+0xa/0x20
>>>     [<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):
>>>   comm "exe", pid 1168, jiffies 4294893410
>>>   backtrace:
>>>     [<ffffffff81121fad>] create_object+0x13d/0x2d0
>>>     [<ffffffff81122265>] kmemleak_alloc+0x25/0x60
>>>     [<ffffffff81119f3b>] __kmalloc+0x16b/0x250
>>>     [<ffffffff811e1d71>] ext4_mb_init+0x1a1/0x590
>>>     [<ffffffff811d2da3>] ext4_fill_super+0x1df3/0x26c0
>>>     [<ffffffff8112774f>] get_sb_bdev+0x16f/0x1b0
>>>     [<ffffffff811c8fd3>] ext4_get_sb+0x13/0x20
>>>     [<ffffffff81127216>] vfs_kern_mount+0x76/0x180
>>>     [<ffffffff8112738d>] do_kern_mount+0x4d/0x130
>>>     [<ffffffff8113fc57>] do_mount+0x307/0x8b0
>>>     [<ffffffff8114028f>] sys_mount+0x8f/0xe0
>>>     [<ffffffff81011f02>] system_call_fastpath+0x16/0x1b
>>>     [<ffffffffffffffff>] 0xffffffffffffffff
>>
>> The ext4 reports are real leaks and patch was posted here -
>> http://lkml.org/lkml/2009/7/15/62. However, it hasn't been merged into
>> mainline yet (I cc'ed Aneesh).
>>
>> The patch is merged in my "kmemleak-fixes" branch on
>> git://linux-arm.org/linux-2.6.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.

These issues seem to be serious blockers, I don't tend to use video
play but I suspect others do, after a decent amount of time playing
the system becomes completely unusable. If you have any other patch
suggestions let me know. I'll try to read the kmemleak docs too, maybe
I can try to figure some of these out.

Luis