From nobody Tue Feb 10 04:23:21 2026 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) (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 071E6263F27; Wed, 23 Apr 2025 01:49:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745372979; cv=none; b=AbkEHGuHGfPMBdE7xpZPzii9GtJX/81yLuYrvqX2gwHvHKHuY2yIJqgIMioAMP2SUIobsEm4mYWF6+QCKwg9k5LcAfZZQATaMDlpnPAPV0Q9qncoN02oNIkdWNmqS9edTpstMpAqD+sriL/Zg72v/yrGs6U0de+fQIo42vQCAiM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745372979; c=relaxed/simple; bh=jMSJ0gf0b0aPu4uBEGao57zRb4usICWr8tS/e0fHtJw=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=VdYk4hEP69Sm3OEdiTjflh5GzFUcyMaj2bRkSkZTpLcZ7Cn1fevaMo1kv2k0VvzVdKJd3tzFJrZWzC8iBB2PzpdFAIWjbmDWWRm4W1t6XVsa8iP4xro6OZjJGPI7XkZ0jNcCv6rKtOcohkNwKYaAyTiakTaOB+oufwPDWnUkT+E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=hDIfCpjq; arc=none smtp.client-ip=91.218.175.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="hDIfCpjq" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1745372973; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=D7+Eeawz4Y8be/9ifCJRuEJtqE9u4PyZ//yEy9tp5gM=; b=hDIfCpjquE1JLYG/4MpX+xVTGu9k+j4qthA+S/jS9mLcZMNR6fspBEDZeuI/O4zCMlPkyP Z5qhwNtkHDuUCJWpPusNB6X5SoGfoJUSXafQalpX/21JzuyG/OqZiVm9yU14C8anogzOJ1 wJ9xXiQb+ouXbvv5z7MY0YlzBQwDU9Y= From: Ye Liu To: akpm@linux-foundation.org Cc: linux-debuggers@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-toolchains@vger.kernel.org, osandov@osandov.com, paulmck@kernel.org, sweettea-kernel@dorminy.me, liuye@kylinos.cn, ye.liu@linux.dev Subject: [PATCH v3] tools/mm: Add script to display page state for a given PID and VADDR Date: Wed, 23 Apr 2025 09:48:50 +0800 Message-Id: <20250423014850.344501-1-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Ye Liu Introduces a new drgn script, `show_page_info.py`, which allows users to analyze the state of a page given a process ID (PID) and a virtual address (VADDR). This can help kernel developers or debuggers easily inspect page-related information in a live kernel or vmcore. The script extracts information such as the page flags, mapping, and other metadata relevant to diagnosing memory issues. Output example: sudo ./show_page_info.py 1 0x7f43df5acf00 PID: 1 Comm: systemd mm: 0xffff8881273bbc40 Raw: 0017ffffc000416c ffffea00043a4508 ffffea0004381e08 ffff88810f086a70 Raw: 0000000000000000 ffff888120c9b0c0 0000002500000007 ffff88812642c000 User Virtual Address: 0x7f43df5acf00 Page Address: 0xffffea00049a0b00 Page Flags: PG_referenced|PG_uptodate|PG_lru|PG_head|PG_active| PG_private|PG_reported Page Size: 16384 Page PFN: 0x12682c Page Physical: 0x12682c000 Page Virtual: 0xffff88812682c000 Page Refcount: 37 Page Mapcount: 7 Page Index: 0x0 Page Memcg Data: 0xffff88812642c000 Memcg Name: init.scope Memcg Path: /sys/fs/cgroup/memory/init.scope Page Mapping: 0xffff88810f086a70 Page Anon/File: File Page VMA: 0xffff88810e4af3b8 VMA Start: 0x7f43df5ac000 VMA End: 0x7f43df5b0000 This page is part of a compound page. This page is the head page of a compound page. Head Page: 0xffffea00049a0b00 Compound Order: 2 Number of Pages: 4 Signed-off-by: Ye Liu Changes in v3: - Adjust display style. - Link to v2:https://lore.kernel.org/all/20250421080748.114750-1-ye.liu@lin= ux.dev/ Changes in v2: - Move the show_page_info.py file to tools/mm. - Link to v1: https://lore.kernel.org/all/20250415075024.248232-1-ye.liu@li= nux.dev/ --- MAINTAINERS | 5 ++ tools/mm/show_page_info.py | 120 +++++++++++++++++++++++++++++++++++++ 2 files changed, 125 insertions(+) create mode 100755 tools/mm/show_page_info.py diff --git a/MAINTAINERS b/MAINTAINERS index 17ed0b5ffdd2..85686a30dc72 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -18351,6 +18351,11 @@ F: Documentation/mm/page_table_check.rst F: include/linux/page_table_check.h F: mm/page_table_check.c =20 +PAGE STATE DEBUG SCRIPT +M: Ye Liu +S: Maintained +F: tools/mm/show_page_info.py + PANASONIC LAPTOP ACPI EXTRAS DRIVER M: Kenneth Chan L: platform-driver-x86@vger.kernel.org diff --git a/tools/mm/show_page_info.py b/tools/mm/show_page_info.py new file mode 100755 index 000000000000..8622c5499dfe --- /dev/null +++ b/tools/mm/show_page_info.py @@ -0,0 +1,120 @@ +#!/usr/bin/env drgn +# SPDX-License-Identifier: GPL-2.0-only +# Copyright (C) 2025 Ye Liu + +import argparse +from drgn import Object +from drgn.helpers.linux import find_task, follow_page, page_size +from drgn.helpers.linux.mm import ( + decode_page_flags, page_to_pfn, page_to_phys, page_to_virt, vma_find, + PageSlab, PageCompound, PageHead, PageTail, compound_head, compound_or= der, compound_nr +) +from drgn.helpers.linux.cgroup import cgroup_name, cgroup_path + +DESC =3D """ +This is a drgn script to show the page state. +For more info on drgn, visit https://github.com/osandov/drgn. +""" + +MEMCG_DATA_OBJEXTS =3D 1 << 0 +MEMCG_DATA_KMEM =3D 1 << 1 +__NR_MEMCG_DATA_FLAGS =3D 1 << 2 + +def format_page_data(data): + """Format raw page data into a readable hex dump.""" + chunks =3D [data[i:i+8] for i in range(0, len(data), 8)] + hex_chunks =3D ["".join(f"{b:02x}" for b in chunk[::-1]) for chunk in = chunks] + lines =3D [" ".join(hex_chunks[i:i+4]) for i in range(0, len(hex_chunk= s), 4)] + return "\n".join(f"Raw: {line}" for line in lines) + +def get_memcg_info(page): + """Retrieve memory cgroup information for a page.""" + memcg_data =3D page.memcg_data.value_() + if memcg_data & MEMCG_DATA_OBJEXTS: + memcg_value =3D 0 + elif memcg_data & MEMCG_DATA_KMEM: + objcg =3D Object(prog, "struct obj_cgroup *", address=3Dmemcg_data= & ~__NR_MEMCG_DATA_FLAGS) + memcg_value =3D objcg.memcg.value_() + else: + memcg_value =3D memcg_data & ~__NR_MEMCG_DATA_FLAGS + + memcg =3D Object(prog, "struct mem_cgroup *", address=3Dmemcg_value) + cgrp =3D memcg.css.cgroup + return cgroup_name(cgrp).decode(), f"/sys/fs/cgroup/memory{cgroup_path= (cgrp).decode()}" + +def show_page_state(page, addr, mm, pid, task): + """Display detailed information about a page.""" + print(f'PID: {pid} Comm: {task.comm.string_().decode()} mm: {hex(mm)}') + print(format_page_data(prog.read(page.value_(), 64))) + fields =3D { + "User Virtual Address": hex(addr), + "Page Address": hex(page.value_()), + "Page Flags": decode_page_flags(page), + "Page Size": page_size(page).value_(), + "Page PFN": hex(page_to_pfn(page).value_()), + "Page Physical": hex(page_to_phys(page).value_()), + "Page Virtual": hex(page_to_virt(page).value_()), + "Page Refcount": page._refcount.counter.value_(), + "Page Mapcount": page._mapcount.counter.value_(), + "Page Index": hex(page.index.value_()), + "Page Memcg Data": hex(page.memcg_data.value_()), + } + + memcg_name, memcg_path =3D get_memcg_info(page) + fields["Memcg Name"] =3D memcg_name + fields["Memcg Path"] =3D memcg_path + fields["Page Mapping"] =3D hex(page.mapping.value_()) + fields["Page Anon/File"] =3D "Anon" if page.mapping.value_() & 0x1 els= e "File" + + vma =3D vma_find(mm, addr) + fields["Page VMA"] =3D hex(vma.value_()) + fields["VMA Start"] =3D hex(vma.vm_start.value_()) + fields["VMA End"] =3D hex(vma.vm_end.value_()) + + # Calculate the maximum field name length for alignment + max_field_len =3D max(len(field) for field in fields) + + # Print aligned fields + for field, value in fields.items(): + print(f"{field}:".ljust(max_field_len + 2) + f"{value}") + + # Additional information about the page + if PageSlab(page): + print("This page belongs to the slab allocator.") + + if PageCompound(page): + print("This page is part of a compound page.") + if PageHead(page): + print("This page is the head page of a compound page.") + if PageTail(page): + print("This page is the tail page of a compound page.") + print(f"{'Head Page:'.ljust(max_field_len + 2)}{hex(compound_head(= page).value_())}") + print(f"{'Compound Order:'.ljust(max_field_len + 2)}{compound_orde= r(page).value_()}") + print(f"{'Number of Pages:'.ljust(max_field_len + 2)}{compound_nr(= page).value_()}") + else: + print("This page is not part of a compound page.") + +def main(): + """Main function to parse arguments and display page state.""" + parser =3D argparse.ArgumentParser(description=3DDESC, formatter_class= =3Dargparse.RawTextHelpFormatter) + parser.add_argument('pid', metavar=3D'PID', type=3Dint, help=3D'Target= process ID (PID)') + parser.add_argument('vaddr', metavar=3D'VADDR', type=3Dstr, help=3D'Ta= rget virtual address in hexadecimal format (e.g., 0x7fff1234abcd)') + args =3D parser.parse_args() + + try: + vaddr =3D int(args.vaddr, 16) + except ValueError: + print(f"Error: Invalid virtual address format: {args.vaddr}") + return + + task =3D find_task(args.pid) + mm =3D task.mm + page =3D follow_page(mm, vaddr) + + if page: + show_page_state(page, vaddr, mm, args.pid, task) + else: + print(f"Address {hex(vaddr)} is not mapped.") + +if __name__ =3D=3D "__main__": + main() \ No newline at end of file --=20 2.25.1