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IDProjectCategoryView StatusLast Update
0014883CentOS-7xorg-x11-serverpublic2018-05-30 03:45
Status newResolutionopen 
PlatformDell Inspiron 5577 laptop x86_64OSCentOSOS Version7.5
Product Version7.5.1804 
Target VersionFixed in Version 
Summary0014883: Xorg crash immediately following synaptics 'if (priv->num_active_touches > priv->num_slots)' BUG
DescriptionAfter yum-updating to latest xorg (1.19.5-5.el7.x86_64) and kernel (3.10.0-862.3.2), two Xorg crashes in about four hours' use. Each immediately (1ms) followed a synaptics BUG 'if (priv->num_active_touches > priv->num_slots)'. Though this BUG doesn't necessarily trigger an immediate crash - there are others in the Xorg.0.log, and only the latest one is immediately followed by the crash.

I'd been using it for months previously without seeing any crashes like these. Before latest update, xorg was 1.19.3, kernel was 3.10.0-693.21.1.

The laptop has a multitouch touchpad.
Steps To ReproduceTry dragging some windows around using multitouch press-and-drag.

Additional InformationAlso, with current configuration, multitouch dragging feels much more erratic. Before, a smooth multitouch finger motion yielded a smoothly dragging window (or whatever). Now, a smooth 2-finger motion for dragging a window yields a window that hops erraticaly between the expected position and other positions, some with the window pressed against the top of the screen, others with the window moved far to the left, etc. Not a crippling problem, but I think this is more troublesome than it used to be, and may be related.
Tagssegfault, X server




2018-05-29 18:34


xorg-2018-05-29-00.48.18.tar.gz (32,689 bytes)
xorg-2018-05-29-11.42.22.tar.gz (32,929 bytes)


2018-05-29 19:25

reporter   ~0031946

Running the CentOS 7.4 kernel 3.10.0-693.21.1 may be a workaround. Simply booting that kernel rather than the current 3.10.0-862.3.2 one, but leaving the xorg server and all the other software unchanged, I see that multitouch dragging behaves in the way it used to - a smooth finger motion yields smooth drag behavior. I'll keep running with this older kernel and see whether it also prevents the xorg crash.

If so, then the difference would seem to be in the events coming from the kernel event driver, right? Would it be useful to run evemu-record using the 7.4 vs 7.5 kernels while doing roughly similar multitouch drag gestures?


2018-05-30 03:45

reporter   ~0031949

Seems stable so far running the 7.5 xorg with the 7.4 kernel. No further crashes yet, and multitouch behaves as expected.

Issue History

Date Modified Username Field Change
2018-05-29 18:34 stuartnlevy New Issue
2018-05-29 18:34 stuartnlevy File Added: xorg-2018-05-29-00.48.18.tar.gz
2018-05-29 18:34 stuartnlevy File Added: xorg-2018-05-29-11.42.22.tar.gz
2018-05-29 18:34 stuartnlevy Tag Attached: segfault
2018-05-29 18:34 stuartnlevy Tag Attached: X server
2018-05-29 19:25 stuartnlevy Note Added: 0031946
2018-05-30 03:45 stuartnlevy Note Added: 0031949