Re: the new VMt

yodaiken
2000-09-25T16:52:47Z

On Mon, Sep 25, 2000 at 04:42:49PM +0100, Stephen C. Tweedie wrote:
> Hi,
>
> On Mon, Sep 25, 2000 at 04:16:56PM +0100, Alan Cox wrote:
> >
> > Unless Im missing something here think about this case
> >
> > 2 active processes, no swap
> >
> > #1 #2
> > kmalloc 32K kmalloc 16K
> > OK OK
> > kmalloc 16K kmalloc 32K
> > block block
> >
>
> ... and we get two wakeup_kswapd()s. kswapd has PF_MEMALLOC and so is
> able to eat memory which processes #1 and #2 are not allowed to touch.
> Progress is made, clean pages are discarded and dirty ones queued for
> write, memory becomes free again and the world is a better place.
>
> Or so goes the theory, at least.

from fs/select.c

walk = out;
while(nfds > 0) {
poll_table *tmp = (poll_table *) __get_free_page(GFP_KERNEL);
if (!tmp) {
while(out != NULL) {
tmp = out->next;
free_page((unsigned long)out);
out = tmp;
}
return NULL;
}
tmp->nr = 0;
tmp->entry = (struct poll_table_entry *)(tmp + 1);
tmp->next = NULL;
walk->next = tmp;
walk = tmp;
nfds -=__MAX_POLL_TABLE_ENTRIES;
}

>
> --Stephen
> -
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--
---------------------------------------------------------
Victor Yodaiken
Finite State Machine Labs: The RTLinux Company.
www.fsmlabs.com www.rtlinux.com