[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[Laurent Bonnaud]

https://bugs.kde.org/show_bug.cgi?id=361521

--- Comment #18 from Laurent Bonnaud  ---
The initial problem described in this bug was about:
1. icon cache
2. /drm mmaped object

Problem 1. is now fixed:

# grep icon-cache /proc/$(pidof plasmashell)/maps | wc -l
  2 

Problem 2. was reported here:
  https://bugs.freedesktop.org/show_bug.cgi?id=99807
and it turns out that this was not a bug.

Therefore I consider that this KDE bug is now fixed and can be closed.

Large virtual memory consumption by baloo is another bug and probably not a bug
either.

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[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[Laurent Bonnaud]

https://bugs.kde.org/show_bug.cgi?id=361521

Laurent Bonnaud  changed:

   What|Removed |Added

 Resolution|--- |FIXED
 Status|UNCONFIRMED |RESOLVED

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[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[Kai Krakow]

https://bugs.kde.org/show_bug.cgi?id=361521

Kai Krakow  changed:

   What|Removed |Added

 CC||k...@kaishome.de

--- Comment #17 from Kai Krakow  ---
(In reply to David Edmundson from comment #12)
> Large virtual memory isn't a problem. It can just mean we've mapped a file
> on disk, even a file that isn't actually that size. We're not using up /any/
> resources by doing it.
> 
> If your resident memory size is high, that's a problem (and the 450Mb is
> high, that we should identify and fix). Virtual memory being high is pretty
> much a non issue until proved otherwise.

You sound pretty sure about this but I'm seeing the same behavior regarding
baloo_index:

7f41b800-7f81b800   r--s268435456 KB20 KB   10 KB   20 KB  
0 KB0 KB0 KB20 KB   0 KB0 KB0 KB0 KB0 KB0 KB   
0 KB0 KB/home/kakra/.local/share/baloo/index

That's around 255GB already. Letting it run a few days more it will eventually
reach 2TB, and that is when my system starts to act strange: The kernel oom
killer kicks in, high memory pressure is reported, file system kernel threads
start to freeze, mouse pointer freezes, until I manage to kill plasmashell. I
guess that such huge virtual memory mappings (although they are sparse and use
almost no real memory) eat up all memory mapping tables and the kernel gets
into trouble finding space in the page tables.

I've once seen plasmashell showing a VMM size of 3.8 TB in top while my system
started to feel very sluggish as if memory pressure forces swapping - but it
wasn't swapping and I had a lot of free physical memory.

Having a RSS of half a gig is absolutely no problem for me. I don't see any
point in chasing that down before the huge VMM size problem was fixed.

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[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[Laurent Bonnaud]

https://bugs.kde.org/show_bug.cgi?id=361521

--- Comment #16 from Laurent Bonnaud  ---
A similar problem exists in the Xorg server and I reported it there:

https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1661934

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[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=361521

988a...@mail.ru changed:

   What|Removed |Added

 CC||988a...@mail.ru

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[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[Laurent Bonnaud]

https://bugs.kde.org/show_bug.cgi?id=361521

--- Comment #15 from Laurent Bonnaud  ---
This "deleted drm mm object" problem is not specific to plasma.  Several other
KDE software have it, the main offender being akregator (see below).

Therefore this is probably a more systemic problem, either in KF5 or Qt.

Process 13064 - akregator

Summary

The process akregator (with pid 13064) is using approximately 316.2 MB of
memory.
It is using 307.7 MB privately, and a further 57.1 MB that is, or could be,
shared with other programs.
Dividing up the shared memory between all the processes sharing that memory we
get a reduced shared memory usage of 8.5 MB. Adding that to the private usage,
we get the above mentioned total memory footprint of 316.2 MB.
14.6 MB is swapped out to disk, probably due to a low amount of available
memory left.
Library Usage

The memory usage of a process is found by adding up the memory usage of each of
its libraries, plus the process's own heap, stack and any other mappings, plus
the stack of its 23 threads. 

Private
276636 KB   [heap]
18296 KB/drm mm object (deleted)
7556 KB /SYSV (deleted)
3460 KB /usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5.7.0
816 KB  /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.7.0

Shared
13276 KB/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5.7.0
4396 KB /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
3268 KB /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.7.0
3212 KB /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.7.0
1492 KB /lib/x86_64-linux-gnu/libc-2.24.so

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[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[Chris Samuel]

https://bugs.kde.org/show_bug.cgi?id=361521

--- Comment #14 from Chris Samuel  ---
(In reply to David Edmundson from comment #12)

> Large virtual memory isn't a problem. It can just mean we've mapped a file
> on disk, even a file that isn't actually that size. We're not using up /any/
> resources by doing it.

OK thanks.

> If your resident memory size is high, that's a problem (and the 450Mb is
> high, that we should identify and fix). Virtual memory being high is pretty
> much a non issue until proved otherwise.

Here is what ksysguard tells me about the breakdown of actual memory usage.

Process 2344 - plasmashell

Summary

The process plasmashell (with pid 2344) is using approximately 452.1 MB of
memory.
It is using 447.7 MB privately, and a further 33.5 MB that is, or could be,
shared with other programs.
Dividing up the shared memory between all the processes sharing that memory we
get a reduced shared memory usage of 4.4 MB. Adding that to the private usage,
we get the above mentioned total memory footprint of 452.1 MB.

Library Usage

The memory usage of a process is found by adding up the memory usage of each of
its libraries, plus the process's own heap, stack and any other mappings, plus
the stack of its 24 threads. 

Private
435808 KB   [heap]
12212 KB/drm mm object (deleted)
1892 KB /home/chris/.cache/plasma_theme_default_v5.25.kcache
[etc]


So basically it's all heap usage, with the deleted DRM objects contributing
just 12MB.

All the best,
Chris

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[plasmashell] [Bug 361521] Numerous deleted DRM mmaped objects

[Laurent Bonnaud]

https://bugs.kde.org/show_bug.cgi?id=361521

Laurent Bonnaud  changed:

   What|Removed |Added

Summary|Large virtual memory|Numerous deleted DRM mmaped
   |consumption and many DRM|objects
   |mmaped objects  |

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