Re: [PATCH RFC] mm: allow __GFP_NOFAIL allocation up to BLK_MAX_BLOCK_SIZE to support LBS

[Michal Hocko <mhocko@suse.com>]

On Tue 04-11-25 13:57:35, Vlastimil Babka wrote:
> On 11/4/25 1:50 PM, Michal Hocko wrote:
> > On Tue 04-11-25 13:32:52, Vlastimil Babka wrote:
> >>
> >> OK, it might not create an order-3 page immediately. But I'd expect it
> >> allows compaction to make progress thanks to making more free memory
> >> available? We do retry reclaim/compaction after OOM killing one process,
> >> and don't just kill until we succeed allocating, right?
> > 
> > Yes we do go through the reclaim/compaction cycle. Do you think this
> > warning is overzealous? Th idea is that a flood of OOMs could be easier
> 
> I think it's too odd to warn for a specific order and not that or higher
> orders. We would risk someone would make the allocation order-4 instead
> of order-3 just to avoid it.

higher orders simply avoid OOM killer so it is effectivelly retry loop
around the allocator. Order-3 is a bit odd and that is what the warning
is trying to tell. But fair enough let's just drop the existing warning
and see how it goes.

-- 
Michal Hocko
SUSE Labs