Re: [PATCH v3 3/3] mm/percpu: Avoid IO/FS reclaim in backing allocations

[Michal Hocko]

On Wed 17-06-26 16:56:56, Kaitao Cheng wrote:
[...]
> __GFP_NOFAIL is actually unnecessary here. The main reason is that,
> for now, I have not found any in-kernel callers that pass __GFP_NOFAIL
> to pcpu_alloc_noprof() or its wrapper functions. The reason I added
> __GFP_NOFAIL was to address the issue reported by sashiko, and I
> provided a detailed clarification in the link below.
> 
> https://lore.kernel.org/all/3de3a89b-92f0-4cd2-9f41-8e853eae4e78@xxxxxxxxx/
> 
> We should probably revert the current patch back to the v2 version,
> and then add some comments explaining why pcpu_alloc_noprof() must
> not be passed the __GFP_NOFAIL flag, as suggested by Andrew Morton.

Do not add support for nofail semantic until there is a clear demand for
it. Supporting this semantic is a big commitment and it shouldn't be
done without a very good usecase in mind.

-- 
Michal Hocko
SUSE Labs