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

[Matthew Wilcox]

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?