From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-m3286.qiye.163.com (mail-m3286.qiye.163.com [220.197.32.86]) (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 97A41314A65 for ; Thu, 30 Apr 2026 16:38:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.32.86 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777567113; cv=none; b=jU8SEqnqV3qODxgbPfqwiYbqxIDuuEGIsPreFZKhGvkWIV2adKwY0MV5JZ+S3gp+ZR2gHQRSX1T0xlbqFSJMZs+0Vlw9i6sDrvxsMrapK1yKSO+2oc5blH1kXEBLU0BYkpLC4p4VmA/iapabFLZDp83ZfWmIswRfmQXrB0vy5Qs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777567113; c=relaxed/simple; bh=Y4jwIQaWvnDQEOi3hJa9jFXWz4A6koSmlB26vm8MvMY=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=AbRXj9a4FOVgxduN7adi5mfOJ98w63L1yAwH0E04hacVhOIiMMnKaKwDdXDHZyDtn+6apo18Tt+9EBRkuqnzvAiN2KFgrApLCF0VXCtQTMLCiVxDgTuXrJ330j6QAEs2grd0NeAoTVeISeoPp9rYxHmxPfTTDj2wrSDkf8yApzE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=easystack.cn; spf=pass smtp.mailfrom=easystack.cn; arc=none smtp.client-ip=220.197.32.86 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=easystack.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=easystack.cn Received: from localhost.localdomain (unknown [IPV6:2409:8a20:e24:8c24:8810:8f74:8c26:2]) by smtp.qiye.163.com (Hmail) with ESMTP id 199a96d4e; Fri, 1 May 2026 00:32:56 +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 v4 0/3] mm/page_owner: add filter infrastructure for print_mode and NUMA filtering Date: Fri, 1 May 2026 00:32:44 +0800 Message-Id: <20260430163247.13628-1-zhen.ni@easystack.cn> X-Mailer: git-send-email 2.20.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9ddf3c7c1f0229kunm7d32d45d8a80 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVkaSB8ZVh1DHk9CHh4dHRlLTFYVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJT0tCQUMaSUtBHklPQUMYSU9BQ0NKS0FDHUxPQUMYSU 1BSVlXWRYaDxIVHRRZQVlPS0hVSktJT09PSFVKS0tVSkJLS1kG This patch series introduces filtering capabilities to the page_owner feature to address storage and performance challenges in production environments. Changes from v3: - Change print_mode from numeric (0/1) to string-based interface * Use "full_stack"/"stack_handle" strings instead of numbers * Display current mode with bracket notation: "[full_stack] stack_handle" - Remove "-1" support from NUMA filter * Use empty string to clear filter (echo > nid) - Use strncpy_from_user() instead of copy_from_user() - Rename nid_filter_fops to page_owner_nid_filter_fops for consistency - Merge patch 1 (infrastructure) and patch 2 (print_mode) from v3 - Update documentation to match new interface * String-based examples * Tab indentation in code blocks Changes from v2: - Remove READ_ONCE/WRITE_ONCE for nodemask_t (fixes compilation errors) * nodemask_t is a large structure (128 bytes) that triggers compile-time asserts * Direct assignment is safe for this use case - Add comment explaining input length calculation formula * 6 bytes = ",NNNNN" (comma + 5-digit node number) - Simplify "-1" check using kstrtoint() instead of dual strcmp() - Move nodemask_t mask read outside PFN iteration loop for performance * Avoids 128-byte structure copy on each iteration - Add documentation for filter features (patch 3/3) Changes from v1: - Renamed 'compact' to 'print_mode' with enum type for better clarity * PAGE_OWNER_PRINT_FULL_STACK (0): print full stack traces * PAGE_OWNER_PRINT_STACK_HANDLE (1): print only stack handles - Changed NUMA filter from single node to nodelist with bitmask support * Uses nodelist_parse() to support "0", "0,2", "0-3", "0,2-4,7" formats * Uses nodemask_t internally for efficient multi-node filtering * Output uses %*pbl format (e.g., "0-2", "0,2-4,7") - Improved memory handling in nid_filter_write using dynamic allocation * Limit: (100 + 6 * MAX_NUMNODES) to handle worst-case input Problem Statement ================= In production environments with large memory configurations (e.g., 250GB+), collecting page_owner information often results in files ranging from several gigabytes to over 10GB. This creates significant challenges: 1. Storage pressure on production systems 2. Difficulty transferring large files from production environments 3. Post-processing overhead with tools/mm/page_owner_sort.c The primary contributor to file size is redundant stack trace information. While the kernel already deduplicates stacks via stackdepot, page_owner retrieves and stores full stack traces for each page, only to deduplicate them again during post-processing. Additionally, in NUMA-aware environments (e.g., DPDK-based cloud deployments where QEMU processes are bound to specific NUMA nodes), OOM events are often node-specific rather than system-wide. Currently, page_owner cannot filter by NUMA node, forcing users to collect and analyze data for all nodes. Solution ======== This patch series introduces a flexible filter infrastructure with two initial filters: 1. **Print Mode Filter**: Outputs only stack handles instead of full stack traces. The handle-to-stack mapping can be retrieved from the existing show_stacks_handles interface. This dramatically reduces output size while preserving all allocation metadata. 2. **NUMA Node Filter**: Allows filtering pages by specific NUMA node(s) using flexible nodelist format, enabling targeted analysis of memory issues in NUMA-aware deployments. Implementation ============== The series is structured as follows: - Patch 1: Implement print_mode filter with string-based interface (merges infrastructure + print_mode from v3) - Patch 2: Implement NUMA node filter with nodelist support - Patch 3: Document filter features Usage Example ============= Enable print_mode and filter for NUMA nodes 0,2-3: # cd /sys/kernel/debug/page_owner_filter/ # echo stack_handle > print_mode # echo "0,2-3" > nid # cat /sys/kernel/debug/page_owner > page_owner.txt Sample print_mode output (showing handles only): Page allocated via order 0, mask 0x0(), pid 0, tgid 0 (swapper), ts 0 ns PFN 0x40000 type Unmovable Block 512 type Unmovable Flags 0x3fffe0000000000(node=0|zone=0|lastcpupid=0x1ffff) handle: 1048577 Page allocated via order 0, mask 0x252000(__GFP_NOWARN| __GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 0, tgid 0 (swapper), ts 0 ns PFN 0x40002 type Unmovable Block 512 type Unmovable Flags 0x23fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff) handle: 1048577 Testing ======= Tested on a system with multiple NUMA nodes. Verified that: - Filters work independently and in combination - Print_mode output correlates correctly with show_stacks_handles - Default behavior (filters disabled) remains unchanged - NUMA filter works with single node, multiple nodes, and ranges - String-based interface works correctly ("full_stack"/"stack_handle") - Empty string clears NUMA filter - Code compiles without warnings or errors (allmodconfig tested) Example test session: # cat print_mode [full_stack] stack_handle # echo stack_handle > print_mode # cat print_mode full_stack [stack_handle] # echo "0,1-2" > nid # cat nid 0-2 # echo "0,2-3" > nid # cat nid 0,2-3 # echo > nid # cat nid (empty - filter cleared) Future Enhancements =================== The filter infrastructure is designed to be extensible. Potential future filters could include: - PID/TGID filtering - Time range filtering (allocation timestamp windows) - GFP flag filtering - Migration type filtering Signed-off-by: Zhen Ni --- Zhen Ni (3): mm/page_owner: add print_mode filter mm/page_owner: add NUMA node filter with nodelist support mm/page_owner: document page_owner filter features Documentation/mm/page_owner.rst | 61 ++++++++++- mm/page_owner.c | 180 +++++++++++++++++++++++++++++++- 2 files changed, 238 insertions(+), 3 deletions(-) -- 2.20.1