[grsec] random x freeze

[fellow]

hi!
i'm using an up-to-date debian sid, on an i386 system with 2.6.11 
vanilla kernel and grsecurity-2.1.3-2.6.11-200503091157.patch 
(high security level).
the xfree86 (4.3.0.dfsg.1-12.0.1) is randomly freezing, after every 
3th or 7th boot. only the x is affected, everything else (net, audio, 
...) seems the work (with the x hangup, the input devices are 
useless). the visual simptom: screen is freezing, only the cursor 
works (looks silly, only rnd b&w dots) or the x is halting and the 
xdm come up (and freezing).
i have done a lot of testing, and it seems the non-executable part of
 the pax is causing the freeze, both segmexec and pageexec (other 
parts of the pax looks no affected: restrict mprotect, kernexec, 
randomize kernel stack).
possibly there is a bug in the video driver (x's built-in nv; fx5600 
card), i'll run tests in vesa mode too.
any other grsec options (like deny writing in /dev/(k)mem) seems to 
be fine.
there is no problem with the 2.6.10-grsec patch or vanilla 2.6.11 
kernel.

fellow

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