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imf08.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=easystack.cn; spf=pass (imf08.hostedemail.com: domain of zhen.ni@easystack.cn designates 156.224.82.135 as permitted sender) smtp.mailfrom=zhen.ni@easystack.cn ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1781755096; b=BvoXDh7up1rlm/noGF5PtCuCcTW7h5+D0Cb0asu8NT01hXWrrzLWdcjEP7Iac46KSaf9Zx qJdjfdOzc2NWtwjDzOALTFo6BvAxGcu4DWwOiqFP7b7h6kNcb4ij7RYQsY14lAPKQaxFRW 639fdq00Y+fHA6Pyjxm/jDvBAcRikY8= Received: from localhost.localdomain (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 1b989993a; Thu, 18 Jun 2026 11:58:12 +0800 (GMT+08:00) From: Zhen Ni To: akpm@linux-foundation.org, vbabka@kernel.org Cc: surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zhen Ni Subject: [PATCH v10 4/4] mm/page_owner: document page_owner filter Date: Thu, 18 Jun 2026 11:57:50 +0800 Message-Id: <20260618035750.3724613-5-zhen.ni@easystack.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260618035750.3724613-1-zhen.ni@easystack.cn> References: <20260618035750.3724613-1-zhen.ni@easystack.cn> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9ed8e11d0c0229kunm88c9600fddaba X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlDGh5JVk4YH0wYQkhOTkMdTVYVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: djf8p9w4w9uo7w7z4j415a4zudwmg6g1 X-Rspamd-Queue-Id: 367A2160003 X-HE-Tag: 1781755095-553081 X-HE-Meta: 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 u+Ifd/MA nrUPQepQHziSWNrVXM/Hgfi0CLZQcT3LfhTH7tBAEHzCYOQXd0C7kJjY7Jf5f0zBUGIRUZc2FAtwpBUTeD7jCebROrifsmlB+X2aD/AMfV20C1uhURpyFP/84pqB1M2LDmYcCmyVZJiwlNj7AyaFxL1AX2nqpLHUmMJq9Qtkj2l5StVQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add documentation for the page_owner_filter userspace tool and kernel-level filtering features. Signed-off-by: Zhen Ni --- Changes in v10: - No changes Changes in v9: - No changes Changes in v8: - Fix Sphinx double colon warning Changes in v7: - document for per-file-descriptor implementation Changes in v6: - No code changes Changes in v5: - No code changes Changes in v4: - Update print_mode documentation to reflect string-based interface * Change from "0/1" to "full_stack"/"stack_handle" * Add bracket notation example: "[full_stack] stack_handle" - Update NUMA filter documentation * Remove "-1" example * Add empty string as clear method - Fix indentation: use tabs instead of spaces in code examples Changes in v3: - New patch to document filter features as requested by Andrew Morton v9: https://lore.kernel.org/linux-mm/20260525081652.2210206-5-zhen.ni@easystack.cn/ v8: https://lore.kernel.org/linux-mm/20260520075641.1931080-5-zhen.ni@easystack.cn/ v7: https://lore.kernel.org/linux-mm/20260515091942.1535677-5-zhen.ni@easystack.cn/ v6: https://lore.kernel.org/linux-mm/20260511033017.747781-4-zhen.ni@easystack.cn/ v5: https://lore.kernel.org/linux-mm/20260507064643.179187-4-zhen.ni@easystack.cn/ v4: https://lore.kernel.org/linux-mm/20260430163247.13628-4-zhen.ni@easystack.cn/ v3: https://lore.kernel.org/linux-mm/20260428071112.1420380-5-zhen.ni@easystack.cn/ --- Documentation/mm/page_owner.rst | 77 ++++++++++++++++++++++++++++++++- 1 file changed, 75 insertions(+), 2 deletions(-) diff --git a/Documentation/mm/page_owner.rst b/Documentation/mm/page_owner.rst index 6b12f3b007ec..383e59c42743 100644 --- a/Documentation/mm/page_owner.rst +++ b/Documentation/mm/page_owner.rst @@ -65,7 +65,14 @@ un-tracking state. Usage ===== -1) Build user-space helper:: +1) Build user-space helpers:: + +To filter page_owner output: + + cd tools/mm + make page_owner_filter + +To sort and analyze page_owner output: cd tools/mm make page_owner_sort @@ -74,7 +81,11 @@ Usage 3) Do the job that you want to debug. -4) Analyze information from page owner:: +4) (Optional) Filter page_owner output:: + + ./page_owner_filter -m handle -n 0,1,2 > filtered_page_owner.txt + +5) Analyze information from page owner:: cat /sys/kernel/debug/page_owner_stacks/show_stacks > stacks.txt cat stacks.txt @@ -263,3 +274,65 @@ STANDARD FORMAT SPECIFIERS f free whether the page has been released or not st stacktrace stack trace of the page allocation ator allocator memory allocator for pages + +Filtering page_owner output +============================ + +page_owner supports filtering output at the kernel level before reading, +which reduces the amount of data that needs to be processed in userspace. + +The page_owner_filter tool provides a convenient interface for this filtering +capability. It supports two types of filters: + +1. **print_mode filter**: Control what information is printed for each page + - ``stack``: Print full stack traces (default, compatible with existing usage) + - ``handle``: Print only stack handle numbers (much faster, smaller output) + - ``stack_handle``: Print both stack traces and handle numbers + + The ``handle`` mode uses numeric identifiers instead of full stack traces. + The mapping from handles to actual stack traces can be obtained via the + show_stacks_handles interface. + +2. **NUMA node filter**: Filter pages by NUMA node ID + - Supports single node: ``-n 0`` + - Multiple nodes: ``-n 0,1,2`` + - Ranges: ``-n 0-3`` + - Mixed format: ``-n 0,2-3,5`` + +Usage examples:: + + # Filter by print mode + ./page_owner_filter -m handle + ./page_owner_filter -m stack_handle + + # Filter by NUMA node + ./page_owner_filter -n 0 + ./page_owner_filter -n 0-3 + + # Combined filters + ./page_owner_filter -m stack -n 0,1,2 + ./page_owner_filter -m handle -n 0,2-3 + + # Save to file + ./page_owner_filter -m handle -o filtered_output.txt + +The handle mode is particularly useful for monitoring and performance-critical +scenarios as it dramatically reduces output size. Testing shows handle mode can +reduce output size by ~66% (84MB vs 244MB) and improve read performance by ~4.4x +compared to full stack output. + +The NUMA node filter is useful for NUMA-aware memory allocation analysis and debugging. + +Behind the scenes, page_owner_filter opens /sys/kernel/debug/page_owner and +writes filter commands before reading the filtered output. The filtering uses +per-file-descriptor state, allowing each open() to have independent filter settings. + +Each file descriptor maintains its own filter state, so you can have multiple +independent filtering operations running concurrently. For example, in different +terminals you can run different filters simultaneously:: + + # Terminal 1: Filter node 0 + ./page_owner_filter -n 0 > node0_output.txt + + # Terminal 2: Filter node 1 (runs concurrently) + ./page_owner_filter -n 1 > node1_output.txt -- 2.20.1