Re: possible IO map leak in drm/gem

[Thomas Zimmermann <tzimmermann@suse.de>]

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(cc'ing dri-devel)

Hi,

thanks for reporting the bug.

Am 21.01.21 um 15:35 schrieb Chuck Lever:
> Hi Thomas-
> 
> I was not able to find an appropriate mailing list entry in MAINTAINERS,

That would be dri-devel@lists.freedesktop.org

> so I'm mailing you directly as committer of record for:
> 
> 43676605f890 ("drm/ttm: Add vmap/vunmap to TTM and TTM GEM helpers")
> 
> I've noticed that since putting v5.11-rc on my test systems, overnight
> on an otherwise idle system the load average seems to grow as the result
> of a kernel worker thread.

Earlier this week I fixed a couple of leaks in that code. Could you 
please apply the patch at [1] and report back if it fixes the issue.

If it's a separate problem, I'll take a closer look.

Best regards
Thomas

[1] 
https://lore.kernel.org/dri-devel/20210118144639.27307-1-tzimmermann@suse.de/

> 
> I used "perf top" to see what it had gotten up to, and it appears that
> it was spending lots of time walking an interval tree on behalf of
> memtype_reserve().
> 
> The most frequently-observed stack trace seems to be:
> 
>       kworker/3:1-2355  [003] 60950.150928: function:             memtype_reserve
>       kworker/3:1-2355  [003] 60950.150942: kernel_stack:         <stack trace>
> => ffffffffc0c66083
> => memtype_reserve (ffffffffa005f9d5)
> => __ioremap_caller (ffffffffa005aac1)
> => ttm_bo_vmap (ffffffffc040f266)
> => drm_gem_vram_vmap (ffffffffc042c5cd)
> => drm_gem_vmap (ffffffffc0506a7f)
> => drm_client_buffer_vmap (ffffffffc0523741)
> => drm_fb_helper_damage_work (ffffffffc049a34a)
> => process_one_work (ffffffffa00dd92e)
> => worker_thread (ffffffffa00dde46)
> => kthread (ffffffffa00e22c4)
> => ret_from_fork (ffffffffa0004192)
> 
> I see a regular call to memtype_reserve(), but never a matching call to
> memtype_free(), thus I suspect a leak of I/O maps in this code.
> 
> --
> Chuck Lever
> 
> 
> 

-- 
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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