Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some configurations?

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some configurations?
Date	2017-07-04 13:00 +0200
Message-ID	<tZtIJ-7a9-9@gated-at.bofh.it> (permalink)
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On Tue 04-07-17 11:39:57, Vlastimil Babka wrote:
> On 07/04/2017 07:23 AM, Joonsoo Kim wrote:
> > On Mon, Jul 03, 2017 at 04:18:01PM +0200, Vlastimil Babka wrote:
> >> allocated" looks much more sane there. But there's a warning nevertheless.
> > 
> > Warning would comes from the fact that drain_all_pages() is called
> > before mm_percpu_wq is initialised. We could remove WARN_ON_ONCE() and add
> > drain_local_page(zone) to fix the problem.
> 
> Wouldn't that still leave some period during boot where kernel already
> runs on multiple CPU's, but mm_percpu_wq is not yet initialized and
> somebody tries to use it? We want to catch such cases, right?

I haven't checked the boot sequence but if we know that we need
mm_percpu_wq initialized earlier than moving it should be not a big deal
I guess.
-- 
Michal Hocko
SUSE Labs

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Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some  configurations? Vlastimil Babka <vbabka@suse.cz> - 2017-07-03 16:20 +0200
  Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some  configurations? Joonsoo Kim <js1304@gmail.com> - 2017-07-04 07:30 +0200
    Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some  configurations? Vlastimil Babka <vbabka@suse.cz> - 2017-07-04 11:50 +0200
      Re: "mm: use early_pfn_to_nid in page_ext_init" broken on some  configurations? Michal Hocko <mhocko@kernel.org> - 2017-07-04 13:00 +0200

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