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s=arc-20220608; d=hostedemail.com; t=1778836806; a=rsa-sha256; cv=none; b=5xkoyGkNYdJrbwm6jpMaccVo/9TPsuykDDxpqT3zw6eSiHIZEHmCbUS1AkBH7iyyl9694U mFrgSEL36LHwWxwD+C6uj3P6SzD3y64Ogs1m8T2lv1k3CrY1yt3ldbRjUtL7tUzVMkjTsY QTNu9Ty2BnMYvG4RamPixwiGTgAmLWI= ARC-Authentication-Results: i=1; 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 156.224.82.152 as permitted sender) smtp.mailfrom=zhen.ni@easystack.cn Received: from localhost.localdomain (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 1a2c1b5b6; Fri, 15 May 2026 17:20:00 +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 v7 4/4] mm/page_owner: document page_owner filter Date: Fri, 15 May 2026 17:19:42 +0800 Message-Id: <20260515091942.1535677-5-zhen.ni@easystack.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260515091942.1535677-1-zhen.ni@easystack.cn> References: <20260515091942.1535677-1-zhen.ni@easystack.cn> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9e2aef84350229kunm2e28cf4e13723d X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlDQkNJVhlMTB5CQh4aHR1JSlYVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 9F56E160009 X-Stat-Signature: ouoaakxdgzazquwt9cbtuusibk9ua8zy X-Rspam-User: X-HE-Tag: 1778836805-314952 X-HE-Meta: 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 koad8JYP cNDXTcwlRWDnd3MiuFAoiyLa2qSWwcZKQxCOIC1XmaJqjUYPOG7UKKx9Gopk4HyQDE9T0Q99KEbe1g0tN32wH4LOeRpbszTSk1espZAzTNlrTclX0U7Qt/6RptYBhU2KCl9GZSh2ugX6YWEUKIv1CFz3mAsm3avPChhn3/dbJ8MfOSlo= 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 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 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..aef1fe561ade 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