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From: SeongJae Park <sj@kernel.org>
Cc: SeongJae Park <sj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	damon@lists.linux.dev, kernel-team@meta.com,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: [RFC PATCH 9/9] Docs/mm/damon/design: update for changed filter-default behavior
Date: Thu, 20 Feb 2025 11:35:09 -0800	[thread overview]
Message-ID: <20250220193509.36379-10-sj@kernel.org> (raw)
In-Reply-To: <20250220193509.36379-1-sj@kernel.org>

DAMOS filters evaluation stages' default behaviors were always allowing
before.  But the previous commits have changed the behavior to be
decided by installed filters.  Update the documentation to clearly
describe it.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/mm/damon/design.rst | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 5af991551a86..ffea744e4889 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -581,9 +581,10 @@ When multiple filters are installed, the group of filters that handled by the
 core layer are evaluated first.  After that, the group of filters that handled
 by the operations layer are evaluated.  Filters in each of the groups are
 evaluated in the installed order.  If a part of memory is matched to one of the
-filter, next filters are ignored.  If the memory passes through the filters
+filter, next filters are ignored.  If the part passes through the filters
 evaluation stage because it is not matched to any of the filters, applying the
-scheme's action to it is allowed, same to the behavior when no filter exists.
+scheme's action to it depends on the last filter's allowance type.  If the last
+filter was for allowing, the part of memory will be rejected, and vice versa.
 
 For example, let's assume 1) a filter for allowing anonymous pages and 2)
 another filter for rejecting young pages are installed in the order.  If a page
@@ -595,11 +596,6 @@ second reject-filter blocks it.  If the page is neither anonymous nor young,
 the page will pass through the filters evaluation stage since there is no
 matching filter, and the action will be applied to the page.
 
-Note that the action can equally be applied to memory that either explicitly
-filter-allowed or filters evaluation stage passed.  It means that installing
-allow-filters at the end of the list makes no practical change but only
-filters-checking overhead.
-
 Below ``type`` of filters are currently supported.
 
 - Core layer handled
-- 
2.39.5


      parent reply	other threads:[~2025-02-20 19:35 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-20 19:35 [RFC PATCH 0/9] mm/damon: make allow filters after reject filters useful and intuitive SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 1/9] mm/damon/core: introduce damos->ops_filters SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 2/9] mm/damon/paddr: support ops_filters SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 3/9] mm/damon/core: support committing ops_filters SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 4/9] mm/damon/core: put ops-handled filters to damos->ops_filters SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 5/9] mm/damon/paddr: support only ops_filters SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 6/9] mm/damon: add default allow/reject behavior fields to struct damos SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 7/9] mm/damon/core: set damos_filter default allowance behavior based on installed filters SeongJae Park
2025-02-27  0:29   ` SeongJae Park
2025-02-20 19:35 ` [RFC PATCH 8/9] mm/damon/paddr: respect ops_filters_default_reject SeongJae Park
2025-02-20 19:35 ` SeongJae Park [this message]

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