Re: [PATCH v3 0/4] mm: clarify nofail memory allocation

[Michal Hocko <mhocko@suse.com>]

On Thu 22-08-24 17:18:29, Linus Torvalds wrote:
> On Thu, 22 Aug 2024 at 17:11, Michal Hocko <mhocko@suse.com> wrote:
> >
> > Let's put whishful thinking aside. Unless somebody manages to go over
> > all existing NOFAIL users and fix them then we should better focus on
> > providing a reasonable clearly documented and enforced semantic.
> 
> I do like changing the naming to make it clear that it's not some kind
> of general MM guarantee for any random allocation.
> 
> So that's why I liked the NOFAIL_SMALL_ALLOC just to make people who
> use it aware that no, they aren't getting a "get out of jail free"
> card.

Small means different things to different people. Also that small has a
completely different meaning for the page allocator and for kvmalloc. I
really do not like to carve any ambiguity like that into the flag that
is supposed to be used for both.

Quite honestly I am not even sure we have actual GFP_NOFAIL users of the
page allocator outside of the MM (e.g. to implement SLUB internal
allocations). git grep just takes too much time to process because the
underlying allocator is not always immediately visible.

Limiting NOFAIL semantic to SLUB and {kv}malloc allocators would make
some sense then as it could enforce reasonable use more easily I guess.
-- 
Michal Hocko
SUSE Labs