Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL

[Barry Song <21cnbao@gmail.com>]

On Tue, Jul 23, 2024 at 11:18 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Mon, Jul 22, 2024 at 11:01:23AM +0200, Michal Hocko wrote:
> > __GFP_$FOO are usually low level. GFP_$FOO are high level and they
> > combine several subflags to have a specific meaning. So this would need
> > to be GFP_NOFAIL. Btw. the same applies to __GFP_NORETRY and
> > __GFP_RETRY_MAYFAIL.
>
> True.  But I think adding GFP_NOFAIL and slowly upping the enforcement
> that no one is using __GFP_NOFAIL directly will get us a similar effect
> to my *_nofail proposal.  It will require manual or scripted checking
> instead of relying on the compiler, but it's much better than what we
> have right now.

I agree. My proposal was actually to enforce blocking in GFP_NOFAIL while the
post code was an ugly hack at the lower level with __GFP_NOFAIL.