Re: [PATCH v1] kernel/trace:check the val against the available mem

[Michal Hocko]

On Thu 05-04-18 07:22:58, Matthew Wilcox wrote:
> On Wed, Apr 04, 2018 at 09:12:52PM -0700, Joel Fernandes wrote:
> > On Wed, Apr 4, 2018 at 7:58 PM, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> > > On Wed, Apr 04, 2018 at 11:47:30AM -0400, Steven Rostedt wrote:
> > >> I originally was going to remove the RETRY_MAYFAIL, but adding this
> > >> check (at the end of the loop though) appears to have OOM consistently
> > >> kill this task.
> > >>
> > >> I still like to keep RETRY_MAYFAIL, because it wont trigger OOM if
> > >> nothing comes in and tries to do an allocation, but instead will fail
> > >> nicely with -ENOMEM.
> > >
> > > I still don't get why you want RETRY_MAYFAIL.  You know that tries
> > > *harder* to allocate memory than plain GFP_KERNEL does, right?  And
> > > that seems like the exact opposite of what you want.
> > 
> > No. We do want it to try harder but not if its already setup for failure.
> 
> I understand you don't want GFP_NORETRY.  But why is it more important for
> this allocation to succeed than other normal GFP_KERNEL allocations?

I guess they simply want a failure rather than OOM even when they can
shoot themselves into head by using oom_origin. It is still quite ugly
to see OOM report...

-- 
Michal Hocko
SUSE Labs