Re: sys_exit() and zap_page_range()

[Philipp Rumpf <prumpf@uzix.org>]

On Tue, Jul 11, 2000 at 01:36:40AM +1000, Andrew Morton wrote:
> Philipp Rumpf wrote:
> > 
> > On Sun, Jul 09, 2000 at 11:54:54PM +0000, Andrew Morton wrote:
> > > Philipp Rumpf wrote:
> > > Hi, Philipp.
> > >
> > > > Here's a simple way:
> > >
> > > Already done it :)  It's apparent that not _all_ callers of z_p_r need
> > > this treatment, so I've added an extra 'do_reschedule' flag.  I've also
> > > moved the TLB flushing into this function.
> > 
> > It is ?  I must be missing something, but it looks to me like all calls
> > to z_p_r can be done out of syscalls, with pretty much any size the user
> > wants.
> 
> Possibly - but I don't want to put reschedules into places unless
> they're demonstrated to cause scheduling stalls.

I disagree with that.  It's a complicated rule.  "Anything a malicious user
can cause to take a lot of time" is a simple rule, and certainly includes
all instances of z_p_r.

> Probably just haven't run the right tests :(

map = mmap(NULL, 0x80000000, PROT_READ|PROT_WRITE, MAP_PRIVATE,
	open("/dev/zero", O_RDONLY), 0);

switch(test) {
case 0:
	munmap(map);
	break;
case 1:
	exit(0);
	break;
case 2:
	read(open("/dev/zero", O_RDONLY), map, 0x8000000);
	break;
}

	Philipp Rumpf
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