Re: [RFC] Arch option to touch newly allocated pages
H. Peter Anvin (hpa@zytor.com)
4 Mar 2002 09:46:55 -0800
Followup to: <200203040504.AAA05343@ccure.karaya.com>
By author: Jeff Dike <jdike@karaya.com>
In newsgroup: linux.dev.kernel
>
> Even with address overcommit management, I can fault if I touch pages when
> tmpfs is full but the system is not near overcommit.
>
> > Furthermore unless you are very careful you may
> > fault again on the stack push for the SIGBUS and if that faults -
> > SIGKILL->OOM time
>
> We are talking about UML kernel stacks. If they have been allocated the way
> I'm proposing with the UML __alloc_pages touching each page on the way out,
> they are allocated on the host, and therefore can't fault.
>
> This seems to me to be sufficiently careful.
>
> One of us is missing something, who is it?
>
I think it's you -- you seem to suffer from the "my application is the
only one that counts" syndrome. If you want to pages dirtied, then
dirty them using memset() or similar.
-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt <amsp@zytor.com>
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