Re: [PATCH 1/5] mm: Add __GFP_NO_OOM_KILL flag

Andrew Morton
2009-05-05T22:37:39Z

On Wed, 6 May 2009 00:19:35 +0200
"Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org> wrote:

> > > + && !processes_are_frozen()) {
> > > if (!try_set_zone_oom(zonelist, gfp_mask)) {
> > > schedule_timeout_uninterruptible(1);
> > > goto restart;
> >
> > Cool, that looks like the semantics of __GFP_NO_OOM_KILL without requiring
> > a new gfp flag. Thanks.
>
> Well, you're welcome.
>
> BTW, I think that Andrew was actually right when he asked if I checked whether
> the existing __GFP_NORETRY would work as-is for __GFP_FS set and
> __GFP_NORETRY unset. Namely, in that case we never reach the code before
> nopage: that checks __GFP_NORETRY, do we?
>
> So I think we shouldn't modify the 'else if' condition above and check for
> !processes_are_frozen() at the beginning of the block below.

Confused.

I'm suspecting that hibernation can allocate its pages with
__GFP_FS|__GFP_WAIT|__GFP_NORETRY|__GFP_NOWARN, and the page allocator
will dtrt: no oom-killings.

In which case, processes_are_frozen() is not needed at all?