Re: [PATCH] mm: page_alloc: document kmemleak's non-blockable __GFP_NOFAIL case

[Yang Shi]

On 7/15/19 8:18 AM, Qian Cai wrote:
> On Mon, 2019-07-15 at 10:01 -0500, Catalin Marinas wrote:
> > On 15 Jul 2019, at 08:17, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> > > On Sat 13-07-19 04:49:04, Yang Shi wrote:
> > > > When running ltp's oom test with kmemleak enabled, the below warning was
> > > > triggerred since kernel detects __GFP_NOFAIL & ~__GFP_DIRECT_RECLAIM is
> > > > passed in:
> > > kmemleak is broken and this is a long term issue. I thought that
> > > Catalin had something to address this.
> > What needs to be done in the short term is revert commit
> > d9570ee3bd1d4f20ce63485f5ef05663866fe6c0. Longer term the solution is to embed
> > kmemleak metadata into the slab so that we donât have the situation where the
> > primary slab allocation success but the kmemleak metadata fails.
> >
> > Iâm on holiday for one more week with just a phone to reply from but feel free
> > to revert the above commit. Iâll follow up with a better solution.
> Well, the reverting will only make the situation worst for the kmemleak under
> memory pressure. In the meantime, if someone wants to push for the mempool

I think this is expected by reverting that commit since kmemleak 
metadata could fail. But, it could fail too even though that commit is 
not reverted if the context is non-blockable.

> solution with tunable pool sizes along with the reverting, that could be an
> improvement.
>
> https://lore.kernel.org/linux-mm/20190328145917.GC10283@xxxxxxxxxxxxxxxxxxxx/