Change eats memory on my server

[Thomas Zimmermann]

Hi

Am 18.01.21 um 08:43 schrieb Christian König:
> Hi Eli,
> 
> have you already tried using kmemleak?
> 
> This sounds like a leak of memory allocated using kmalloc(), so kmemleak 
> should be able to catch it.

I have an idea what happens here. When the refcount is 0 in kmap, a new 
page mapping for the BO is being established. But VRAM helpers unmap the 
previous pages only on BO moves or frees; not in kunmap. So the old 
mapping might still be around. I'll send out a test patch later today.

Best regards
Thomas

> 
> Regards,
> Christian.
> 
> Am 17.01.21 um 06:08 schrieb Eli Cohen:
>> On Fri, Jan 15, 2021 at 10:03:50AM +0100, Thomas Zimmermann wrote:
>>> Could you please double-check that 3fb91f56aea4 ("drm/udl: Retrieve USB
>>> device from struct drm_device.dev") works correctly
>> Checked again, it does not seem to leak.
>>
>>> and that 823efa922102
>>> ("drm/cma-helper: Remove empty drm_gem_cma_prime_vunmap()") is broken?
>>>
>> Yes, this one leaks, as does the one preceding it:
>>
>> 1086db71a1db ("drm/vram-helper: Remove invariant parameters from 
>> internal kmap function")
>>> For one of the broken commits, could you please send us the output of
>>>
>>>    dmesg | grep -i drm
>>>
>>> after most of the memory got leaked?
>>>
>> I ran the following script in the shell:
>>
>> while true; do cat /proc/meminfo | grep MemFree:; sleep 5; done
>>
>> and this is what I saw before I got disconnected from the shell:
>>
>> MemFree:          148208 kB
>> MemFree:          148304 kB
>> MemFree:          146660 kB
>> Connection to nps-server-24 closed by remote host.
>> Connection to nps-server-24 closed.
>>
>>
>> I also mointored the output of dmesg | grep -i drm
>> The last output I was able to save on disk is this:
>>
>> [   46.140720] ast 0000:03:00.0: [drm] Using P2A bridge for configuration
>> [   46.140737] ast 0000:03:00.0: [drm] AST 2500 detected
>> [   46.140754] ast 0000:03:00.0: [drm] Analog VGA only
>> [   46.140772] ast 0000:03:00.0: [drm] dram MCLK=800 Mhz type=7 
>> bus_width=16
>> [   46.153553] [drm] Initialized ast 0.1.0 20120228 for 0000:03:00.0 
>> on minor 0
>> [   46.165097] fbcon: astdrmfb (fb0) is primary device
>> [   46.391381] ast 0000:03:00.0: [drm] fb0: astdrmfb frame buffer device
>> [   56.097697] systemd[1]: Starting Load Kernel Module drm...
>> [   56.343556] systemd[1]: modprobe at drm.service: Succeeded.
>> [   56.350382] systemd[1]: Finished Load Kernel Module drm.
>> [13319.469462] [   2683] 70889  2683    55586        0    73728      
>> 138             0 tdrm
>> [13320.658386] [   2683] 70889  2683    55586        0    73728      
>> 138             0 tdrm
>> [13321.800970] [   2683] 70889  2683    55586        0    73728      
>> 138             0 tdrm
> 
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-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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