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imf05.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=easystack.cn; spf=pass (imf05.hostedemail.com: domain of zhen.ni@easystack.cn designates 156.224.82.4 as permitted sender) smtp.mailfrom=zhen.ni@easystack.cn ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779697035; a=rsa-sha256; cv=none; b=a6rJ2MF8ZmtPG3OxjqJbboGH0Ewg8wwIbI8NM/ECoD0e0DNBi4ZVBty7S/yzKISFOwS9sb T9iXI7nBNQM72puq2zHSiBo+dKAe68hZNFn3jbP+37W+PE++4JxWLABKnVk8ZQFOOU58qy btnqN4X/GLYmLgHlbYxPrBcbuPxe1r0= Received: from localhost.localdomain (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 1a8ce5e0f; Mon, 25 May 2026 16:17:10 +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 v9 4/4] mm/page_owner: document page_owner filter Date: Mon, 25 May 2026 16:16:52 +0800 Message-Id: <20260525081652.2210206-5-zhen.ni@easystack.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260525081652.2210206-1-zhen.ni@easystack.cn> References: <20260525081652.2210206-1-zhen.ni@easystack.cn> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9e5e3596f80229kunm9b83604117f150 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlDT09DVh1DTUNCQxpDHh1ITFYVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3C19310000A X-Rspam-User: X-Stat-Signature: sk9a7cw73nf53rk5t8i8tmfugfczadbd X-HE-Tag: 1779697034-203833 X-HE-Meta: U2FsdGVkX1/7o/qYVKdkilAktLScUmEtyxkWBN8KrLqaaygUiOmT+sakExWs2paqxtnvoCjT4ZKv+c7MKEMesToye6VUG2JqUaigkeF6wbeWQbyEiYyW9gMGTVMSXRA9CLGHyWlwZn+oHiv6F3GXQwrp7k7QeGdJZQurZnRD3tYFEHRiC6EUSr0u4sDjet2EAt4TtgczSc0vDQ5XMEAf6ySAwG7z0R7ZWGSucnivjQQRonGrL+RFfpoOWG5uqAm4DHlQAdvKMgK0nhvSPJcGjvsCcwlaDiU3p3XSXNNLc7/G3h664jYNkjOFW2mKHqlmW2KFHHL4E7GLnEDuoiLcknyUHblJ7b5WLdH2fhf8DcBFtF0cYOW7iR6f8zX09yibeZRUKuChm5RDe3/+ZiII+nak2Jpl4k1CbA1mXQJwIXmmJIE/OukqL2sH4cw6J+xa6A1G7+h4/Jd06KwmVr8A+njeTLQjFiW7rOTxEpAv4nM44XZip8v2OktIbGQELGTy/5PU6Z+jmWP2cSxJEH5TKknVegomZbhjqvhy0Lrn0iBk1vrSnRzt8jztFcPtFupprQk1QVDty3UIuAVbgBHitX1OyqKVeLtP9kKSd7lDp9SOsrdMiKZchNcso139Q62u/u6+ixUWKFDpgdITn67Hsqqwfnvhxg2k8SaZZn9ZS7hmY2WfQOz7zsPwaETX7cwd7hFTuGCBE0JDBXZmONI3aP1WrDdPvUAdO23ubdA/T7nRaiSJbTFBXFtJ4Mu/GhTCGNiak2kpsApAMjjFARpjw54RGVSxDyXt7Gk01bk6bzv8YcO6OHygvWwymarjcyxZPO0dtoOzUaZdEjyNCukeNJs+tZm4Cw6NieyPDrHKmrUosJ+dLwm3E4IEQ4uDF26xq8erT4GqzXwXaZojEDkJaHYL1w17DuR7SMy0qE4TybZtWpoC8nyI09gyZk4Qhr6FTxgLNovekbe2IBlpPem Zmpnu65r oT9JmERbQtiXS04pzrFDMyixjMVq7emIxVtshjq3LoB2GYAoqiWBalHYFzzttl32vq2h4uDjHHGAbSVWdIV0bQtOrQk1Wzb8Idy4hyNFgdKox1keGXlo4ysD75/FcFFiveMViv5GmKQH7lRACwJlS+bm/WnFHvDQV9Nthaa4QT7iBFeM= 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 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 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