On 08/28, Nick Piggin wrote:
>
> On Sun, Aug 27, 2006 at 10:25:38PM +0400, Oleg Nesterov wrote:
> >
> > - releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
> > - p->flags & PF_EXITING;
> > - if (releasing) {
> > - if (p->flags & PF_EXITING && p == current) {
> > - chosen = p;
> > - *ppoints = ULONG_MAX;
> > - break;
> > - }
> > - return ERR_PTR(-1UL);
> > - }
> > + if ((p->flags & PF_EXITING) && p == current) {
> > + chosen = p;
> > + *ppoints = ULONG_MAX;
> > + break;
> > + }
> > + if ((p->flags & PF_EXITING) ||
> > + test_tsk_thread_flag(p, TIF_MEMDIE))
> > + return ERR_PTR(-1UL);
> > +
>
> Hmm, actually I think I spot a bug in the original logic: we don't want
> to have more than 1 task with TIF_MEMDIE at once, becaues that gives it
> access to memory reserves (but I saw it first in the new formulation, so
> maybe that does suggest it is more readable ;)
>
> What I think should be done is the check for TIF_MEMDIE (and return -1)
> first, and then the PF_EXITING test. At which point, if current is found to
> be exiting, it should be chosen but not break... that way a subsequent MEMDIE
> or EXITING task has the chance to trigger the -1 return.
Aha! The logic looked somewhat strange to me, but ...
> Anyway, if you don't want to do all that, I will when my hand gets better.
I have little understanding of this magic, i'd better not to try to fix it.
> Otherwise the 3 patches you sent look good, they could all have an
>
> Acked-by: Nick Piggin <[email protected]>
Thanks!
Oleg.
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