a Linux swap storm

[<Andries.Brouwer@cwi.nl>]

Earlier this evening I showed someone some pictures under X:

% display -size 300x300 *.jpg

(395 pictures, 315 MB). When display (from ImageMagick)
started to repeat, I exited the program.
At this moment the machine became unusable for twenty minutes
of solid disk activity.
No keystroke seen, not even the Ctrl-Alt-Backspace to kill X,
or Ctrl-Alt-F1 to switch consoles, no mouse movement seen,
vmstat did not produce any output for twenty minutes.

The vmstat 5 output was

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa

 0  3 315728   3164   4424   3356  646  382   792   382 2425   182  0  5  0 95
 1  1 316356   3856   4428   3572  454  366   507   366 2242   150  0  5  0 95
 0  1 317540   3784   4456   3664  530  578   590   578 2403   179  0  7  0 93
 0  1 306740   4240   4524   5372 127013 49878 129427 50061 405016 32901  0  4  0 95
 1  1 306712   3992   4536   5372   30    0    30     3  450   122  2  1 94  2
 0  0 306692   4016   4548   5372   18    0    18     3  402   134  2  2 96  1
 0  0 306692   4016   4560   5372    0    0     0     3  257    35  1  1 98  0

The machine is vanilla 2.6.14, 256MB, 550MB swap.

% rpm -qf `which X`
xorg-x11-server-6.8.2-100

I wonder what precisely happened. Is this an X bug? Or a kernel bug?
The effect is reproducible.

Andries

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