linux-kernel - Re: [PATCH v3] mm/page_owner: fix for deferred struct page init

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Message-ID: <20190108224026.GL31793@dhcp22.suse.cz>
Date:   Tue, 8 Jan 2019 23:40:26 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Qian Cai <cai@....pw>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Pavel.Tatashin@...rosoft.com, mingo@...nel.org,
        mgorman@...hsingularity.net, iamjoonsoo.kim@....com,
        tglx@...utronix.de, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] mm/page_owner: fix for deferred struct page init

On Tue 08-01-19 17:13:41, Qian Cai wrote:
> 
> 
> On 1/8/19 5:02 PM, Andrew Morton wrote:
> > 
> > It's unclear (to me) where we stand with this patch.  Shold we proceed
> > with v3 for now, or is something else planned?
> 
> I don't have anything else plan for this right now. Michal particular don't like
> that 4-line ifdef which supposes to avoid an immediately regression (arguably
> small) that existing page_owner users with DEFERRED_STRUCT_PAGE_INIT deselected
> that would start to miss tens of thousands early page allocation call sites. So,
> feel free to choose v2 of this which has no ifdef if you agree with Michal too.
> I am fine either way.

Yes I would prefer to revert the faulty commit (fe53ca54270) and work on
a more robust page_owner initialization to cover earlier allocations on
top of that.

Not that I would insist but this would be a more straightforward
approach and I hope it will result in a better long term maintainable
code in the end.

-- 
Michal Hocko
SUSE Labs