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Date: Mon, 29 Jan 2024 17:28:47 +0100
From: Michal Hocko <mhocko@suse.com>
To: Lance Yang <ioworker0@gmail.com>
Cc: akpm@linux-foundation.org, zokeefe@google.com, david@redhat.com,
	songmuchun@bytedance.com, shy828301@gmail.com, peterx@redhat.com,
	minchan@kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] mm/khugepaged: bypassing unnecessary scans with
 MMF_DISABLE_THP check
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On Mon 29-01-24 13:45:51, Lance Yang wrote:
> khugepaged scans the entire address space in the
> background for each given mm, looking for
> opportunities to merge sequences of basic pages
> into huge pages. However, when an mm is inserted
> to the mm_slots list, and the MMF_DISABLE_THP flag
> is set later, this scanning process becomes
> unnecessary for that mm and can be skipped to avoid
> redundant operations, especially in scenarios with
> a large address space.

Is this a real problem? I thought that the prctl is called
on the parent before fork/exec. Or are you aware of any
applications which do call prctl late enough that the race
would be actually observable?
-- 
Michal Hocko
SUSE Labs