linux-kernel - Re: [PATCH] mm/compaction: do not break pages whose order is larger than target order

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Message-ID: <20250425153232.GA108388@cmpxchg.org>
Date: Fri, 25 Apr 2025 11:32:32 -0400
From: Johannes Weiner <hannes@...xchg.org>
To: Wenchao Hao <haowenchao22@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/compaction: do not break pages whose order is larger
 than target order

On Fri, Apr 25, 2025 at 10:28:42PM +0800, Wenchao Hao wrote:
> On Fri, Apr 25, 2025 at 3:42 AM Johannes Weiner <hannes@...xchg.org> wrote:
> >
> > On Thu, Apr 24, 2025 at 11:38:15PM +0800, Wenchao Hao wrote:
> > > When scanning free pages for memory compaction, if the compaction target
> > > order is explicitly specified, do not split pages in buddy whose order
> > > are larger than compaction target order.
> >
> > Have you observed this to be an issue in practice?
> >
> > compact_finished() would have bailed if such a page had existed.
> >
> 
> Yes, when proactive memory compaction is enabled, there may be situations
> where the order of isolated free pages is greater than the compaction
> requested order, and compact_finished() will return continue.

proactive compaction has an order of -1?