From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9401D27AC28 for ; Sun, 29 Mar 2026 00:42:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774744951; cv=none; b=WZvvyw6uHcwT3gGiB+ObqM8CKoEbM1H0ro61aJq0+aD3gM48I158TkraW5dfRzrQd6If9fzcRcLu2vx/cS6eD6CSf6EgFH9oaUff4pis2RzfceJqOi9nZsycwdvWOmC79ThbJc9YIy/Uv769egRwgdiK0od7lHW5JxEDCRJTNVk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774744951; c=relaxed/simple; bh=K773nc7Px1O/sOHae3Bcfixfa7coXxGRUsv5eMFU0uY=; h=Date:To:From:Subject:Message-Id; b=WETb3G39XZSbjA4o+uhmLKVKHBCgF5IkUCsGy2jR/qU/3BdR6Gn+yyKdb9Orz0wfKcomSKA8tRkfEALrr9qScLFIfxkxS/Um+HLyrw5d9fB8fWjU9DgOgoNhmPVJZastEk8eSefvPNaroRChhaAhp5szisJwC+05Vy6aKNuYINY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=09rFRH7X; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="09rFRH7X" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BEC7C4CEF7; Sun, 29 Mar 2026 00:42:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1774744951; bh=K773nc7Px1O/sOHae3Bcfixfa7coXxGRUsv5eMFU0uY=; h=Date:To:From:Subject:From; b=09rFRH7XB9NQHkFypOXMi4/1GM38ej/u+xSyQ/37ltlBr4451JA5B4FbabGc4uZpS uJAmoUqSb5FI2TQ2FNm/rx1h0WX4C+AY2Zc6cV7jtz4wGrfzgiyoNItMXqg/jdyerG 7kdSBAbB+JDtUwBsoP13ylXw/bdkAZqFhVUiIqVE= Date: Sat, 28 Mar 2026 17:42:30 -0700 To: mm-commits@vger.kernel.org,sj@kernel.org,aethernet65535@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] docs-mm-damon-document-min_nr_regions-constraint-and-rationale.patch removed from -mm tree Message-Id: <20260329004231.6BEC7C4CEF7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: Docs/mm/damon: document min_nr_regions constraint and rationale has been removed from the -mm tree. Its filename was docs-mm-damon-document-min_nr_regions-constraint-and-rationale.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Liew Rui Yan Subject: Docs/mm/damon: document min_nr_regions constraint and rationale Date: Fri, 20 Mar 2026 13:24:28 +0800 The current DAMON implementation requires 'min_nr_regions' to be at least 3. However, this constraint is not explicitly documented in the admin-guide documents, nor is its design rationale explained in the design document. Add a section in design.rst to explain the rationale: the virtual address space monitoring design needs to handle at least three regions to accommodate two large unmapped areas. While this is specific to 'vaddr', DAMON currently enforces it across all operation sets for consistency. Also update reclaim.rst and lru_sort.rst by adding cross-references to this constraint within their respective 'min_nr_regions' parameter description sections, ensuring users are aware of the lower bound. This change is motivated from a recent discussion [1]. Link: https://lkml.kernel.org/r/20260320052428.213230-1-aethernet65535@gmail.com Link: https://lore.kernel.org/damon/20260319151528.86490-1-sj@kernel.org/T/#t [1] Signed-off-by: Liew Rui Yan Reviewed-by: SeongJae Park Signed-off-by: Andrew Morton --- Documentation/admin-guide/mm/damon/lru_sort.rst | 4 ++++ Documentation/admin-guide/mm/damon/reclaim.rst | 4 ++++ Documentation/mm/damon/design.rst | 7 +++++++ 3 files changed, 15 insertions(+) --- a/Documentation/admin-guide/mm/damon/lru_sort.rst~docs-mm-damon-document-min_nr_regions-constraint-and-rationale +++ a/Documentation/admin-guide/mm/damon/lru_sort.rst @@ -221,6 +221,10 @@ But, setting this too high could result Please refer to the DAMON documentation (:doc:`usage`) for more detail. 10 by default. +Note that this must be 3 or higher. Please refer to the :ref:`Monitoring +` section of the design document for the rationale +behind this lower bound. + max_nr_regions -------------- --- a/Documentation/admin-guide/mm/damon/reclaim.rst~docs-mm-damon-document-min_nr_regions-constraint-and-rationale +++ a/Documentation/admin-guide/mm/damon/reclaim.rst @@ -204,6 +204,10 @@ monitoring. This can be used to set low But, setting this too high could result in increased monitoring overhead. Please refer to the DAMON documentation (:doc:`usage`) for more detail. +Note that this must be 3 or higher. Please refer to the :ref:`Monitoring +` section of the design document for the rationale +behind this lower bound. + max_nr_regions -------------- --- a/Documentation/mm/damon/design.rst~docs-mm-damon-document-min_nr_regions-constraint-and-rationale +++ a/Documentation/mm/damon/design.rst @@ -167,6 +167,13 @@ monitoring attributes, ``sampling interv ``update interval``, ``minimum number of regions``, and ``maximum number of regions``. +Note that ``minimum number of regions`` must be 3 or higher. This is because the +virtual address space monitoring is designed to handle at least three regions to +accommodate two large unmapped areas commonly found in normal virtual address +spaces. While this restriction might not be strictly necessary for other +operation sets like ``paddr``, it is currently enforced across all DAMON +operations for consistency. + To know how user-space can set the attributes via :ref:`DAMON sysfs interface `, refer to :ref:`monitoring_attrs ` part of the documentation. _ Patches currently in -mm which might be from aethernet65535@gmail.com are