Re: [PATCH] mm: allow __GFP_RETRY_MAYFAIL in vmalloc

[Michal Hocko <mhocko@suse.com>]

On Tue 24-02-26 06:22:15, Shakeel Butt wrote:
> On Tue, Feb 24, 2026 at 06:03:13AM -0800, Christoph Hellwig wrote:
> > On Tue, Feb 24, 2026 at 01:22:36PM +0100, Michal Hocko wrote:
> > > One thing that we could do to improve __GFP_RETRY_MAYFAIL resp.
> > > __GFP_NORETRY is to use NOWAIT allocation semantic for page table
> > > allocations as those could be achieved by scoped allocation context.
> > > This could cause pre-mature failure after the whole bunch of memory has
> > > already been allocated for the backing pages but considering that page
> > > table allocations should be more and more rare over system runtime it
> > > might be just a reasonable workaround. WDYT?
> > 
> > Why bother?  __GFP_RETRY_MAYFAIL has pretty lose semantics.  Trying
> > too hard to allocate PTEs is not breaking the overall concept.
> > 
> 
> One thing __GFP_RETRY_MAYFAIL is very clear about is to not trigger the
> oom-killer which is not the case for GFP_KERNEL. There are users who explicitly
> use __GFP_RETRY_MAYFAIL to avoid oom-killer.
> 
> Mikulas, is that the reason you are using __GFP_RETRY_MAYFAIL in your use-case?

yes https://lore.kernel.org/all/32bd9bed-a939-69c4-696d-f7f9a5fe31d8@redhat.com/T/#u
-- 
Michal Hocko
SUSE Labs