Bug 99807

Summary:	Numerous deleted DRM mmaped objects in Xorg server memory mappings
Product:	xorg	Reporter:	Laurent Bonnaud <L.Bonnaud>
Component:	Driver/intel	Assignee:	Chris Wilson <chris>
Status:	RESOLVED FIXED	QA Contact:	Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Laurent Bonnaud 2017-02-14 08:50:03 UTC

Hi,

here is the problem:

# grep /drm /proc/$(pidof Xorg)/maps
7f4afc942000-7f4afc94a000 rw-s 00000000 00:05 293242                     /drm mm object (deleted)
7f4afc9a4000-7f4afc9ac000 rw-s 00000000 00:05 292174                     /drm mm object (deleted)
7f4b009d8000-7f4b009e0000 rw-s 00000000 00:05 292169                     /drm mm object (deleted)
7f4b00b4c000-7f4b00b50000 rw-s 00000000 00:05 292165                     /drm mm object (deleted)
7f4b00b52000-7f4b00b53000 rw-s 00000000 00:05 292159                     /drm mm object (deleted)


This is just after the Xorg server has been started by lightdm.  At other times the number of deleted mappings can be much higher.

Those deleted mappings should probably not be there and waste memory.

Comment 1 Laurent Bonnaud 2017-02-14 08:54:16 UTC

Here are more specific bug reports with all the details:

 - Debian with Xorg 1.19.1:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=855105

 - Ubuntu with Xorg 1.18.4:
https://bugs.launchpad.net/xorg-server/+bug/1661934

Comment 2 Laurent Bonnaud 2018-02-23 12:09:31 UTC

The problem is still there in more recent version, but in a slightly different form:

# grep i915 /proc/$(pidof Xorg)/maps
7f37de9ce000-7f37dedce000 rw-s 00000000 00:18 64439                      /i915 (deleted)
7f37e2f2e000-7f37e2fae000 rw-s 00000000 00:18 1260390                    /i915 (deleted)
7f37e3396000-7f37e3b96000 rw-s 00000000 00:18 37015                      /i915 (deleted)
7f37ebeed000-7f37ebefd000 rw-s 00000000 00:18 104879                     /i915 (deleted)
7f37ebf0d000-7f37ebf15000 rw-s 00000000 00:18 1263772                    /i915 (deleted)
7f37f28d7000-7f37f28df000 rw-s 00000000 00:18 1262549                    /i915 (deleted)
7f37f28e2000-7f37f28e3000 rw-s 00000000 00:18 54294                      /i915 (deleted)
7f37f28e3000-7f37f28e4000 rw-s 00000000 00:18 38653                      /i915 (deleted)
7f37f28e4000-7f37f28e5000 rw-s 00000000 00:18 40964                      /i915 (deleted)
7f37f28e5000-7f37f28e6000 rw-s 00000000 00:18 40226                      /i915 (deleted)
7f37f28e6000-7f37f28e7000 rw-s 00000000 00:18 40225                      /i915 (deleted)
7f37f28e7000-7f37f28f7000 rw-s 00000000 00:18 38652                      /i915 (deleted)
7f37f28f7000-7f37f28f8000 rw-s 00000000 00:18 1250238                    /i915 (deleted)
7f37f28fb000-7f37f28fc000 rw-s 00000000 00:18 757881                     /i915 (deleted)
7f37f28fc000-7f37f28fd000 rw-s 00000000 00:18 757880                     /i915 (deleted)
7f37f28fd000-7f37f28fe000 rw-s 00000000 00:18 757879                     /i915 (deleted)
7f37f28fe000-7f37f28ff000 rw-s 00000000 00:18 757878                     /i915 (deleted)
7f37f28ff000-7f37f2907000 rw-s 00000000 00:18 1261547                    /i915 (deleted)
7f37f2907000-7f37f290f000 rw-s 00000000 00:18 1263683                    /i915 (deleted)
7f37f2910000-7f37f2911000 rw-s 00000000 00:18 757877                     /i915 (deleted)
7f37f2911000-7f37f2912000 rw-s 00000000 00:18 45058                      /i915 (deleted)
7f37f2a2f000-7f37f2a30000 rw-s 00000000 00:18 1254529                    /i915 (deleted)
7f37f2a34000-7f37f2a35000 rw-s 00000000 00:18 38657                      /i915 (deleted)
7f37f2a35000-7f37f2a36000 rw-s 00000000 00:18 38655                      /i915 (deleted)
7f37f2a36000-7f37f2a37000 rw-s 00000000 00:18 757876                     /i915 (deleted)
7f37f2a37000-7f37f2a38000 rw-s 00000000 00:18 757875                     /i915 (deleted)
7f37f2a38000-7f37f2a39000 rw-s 00000000 00:18 757874                     /i915 (deleted)
7f37f2a3e000-7f37f2a3f000 rw-s 00000000 00:18 866965                     /i915 (deleted)
7f37f2a79000-7f37f2a81000 rw-s 00000000 00:18 36441                      /i915 (deleted)

Comment 3 Laurent Bonnaud 2018-02-23 12:19:03 UTC

Since the problem seems specific to Intel GPUs, I'm changing the bug's component.

Comment 4 Chris Wilson 2018-02-23 12:27:21 UTC

The mappings are still in use, when their usage count drops to zero then they are reclaimed.

Comment 5 Laurent Bonnaud 2018-02-23 13:00:04 UTC

Thanks for the explanation!

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