Re: [stable] 2.6.16.6 breaks java... sort of

[Hugh Dickins <hugh@veritas.com>]

On Wed, 19 Apr 2006, Greg KH wrote:
> On Wed, Apr 19, 2006 at 12:52:33PM -0600, David Wilk wrote:
> > 
> > I think an issue was introduced with mprotect (the first patch in
> > 2.6.16.6).  With 2.6.16.5, tomcat runs fine (in sun-1.5), but in
> > 2.6.16.7, the JVM bails out complaining that it couldn't allocate
> > enough heap space.
> > 
> > If I remove '-Xmx768m' from JAVA_OPTS, then the JVM is able to
> > startup.  The machine had 1GB of RAM and 2GB of swap, so it should
> > have had plenty to give the JVM the 1GB it expects to get with an Xmx
> > of 768MB, and this worked in 2.6.16.5 and below.
> > 
> > I don't know if this is expected and satisfactory behavior, but I
> > figured I should give ya'll the heads up.
> 
> Odds are it isn't "expected", but Hugh would be the best judge of that.
> Hugh?

Neither expected nor satisfactory.  Sorry about that.  We were hoping
the straightforward shm/mprotect fix would be good enough, but it
appears not.  JVM is probably doing something we can allow with a
more complicated patch, but it _might_ turn out to be doing something
we simply cannot allow: I'll hope for the first and work out a patch
for that; but won't be ready to post it until tomorrow.

If you can get an strace of what it's doing, David, please mail that
to me; but I'm guessing that it may be hard to get, and dispiritingly
large: so don't worry unless it's easy for you.

> thanks for letting us know about this,

Indeed, and sorry for the inconvenience.

Hugh