hanging process: state `layerf'

[Jukka Salmi <j+nbsd%2009.salmi.ch@localhost>]

[While I see this problem on netbsd-5 (can't try with HEAD ATM), I think
this is the right place to ask since the problem seems to be a
regression caused by a recent pull-up.)

Hello,

since I updated the kernel of a NetBSD/i386 5.0_STABLE system yesterday I'm
seeing processes hanging forever (or just longer than my patience lasts...).
So far this seems to be reproducible by e.g. building parts of a NetBSD
release; the build process soon hangs and top(1) shows a make(1) process in
state `layerf' (and some others queueing):

load averages:  1.00,  0.75,  0.36;         up 0+00:10:06            10:12:14
49 processes: 2 runnable, 45 sleeping, 2 on CPU
CPU0 states:  0.0% user,  0.0% nice,  0.8% system,  1.6% interrupt, 97.7% idle
CPU1 states:  0.8% user,  0.0% nice, 18.6% system,  0.0% interrupt, 80.6% idle
Memory: 165M Act, 13M Inact, 6440K Wired, 21M Exec, 97M File, 1258M Free
Swap: 2048M Total, 2048M Free

  PID USERNAME PRI NICE   SIZE   RES STATE      TIME   WCPU    CPU COMMAND
 1159 build    125    0  3852K 2252K layerf/1   0:00  0.00%  0.00% nbmake
 1187 build     85    0  3852K 2212K wait/1     0:00  0.00%  0.00% nbmake
 5296 build     85    0  2828K 1576K wait/1     0:00  0.00%  0.00% nbmake
 2374 build     85    0  2948K  956K wait/1     0:00  0.00%  0.00% sh
 1189 build     85    0  2948K  924K wait/1     0:00  0.00%  0.00% sh
  660 build     85    0  2824K  916K pause/1    0:00  0.00%  0.00% ksh


With the old kernel I can't reproduce this problem; a diff(1) of ident(1)
outputs of both old (working) and new (buggy) kernels is available [1]here.
One of those changes must be the culprit...

Anybody else seing the same?  What does state `layerf' mean?  Any hints?


TIA, Jukka

[1] http://salmi.ch/~jukka/nbsd/ident_hangproc.diff

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