From nobody Sun Dec 14 19:20:31 2025 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (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 3F6901C6FE5 for ; Mon, 21 Apr 2025 08:08:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745222890; cv=none; b=laAEZIhzNLL3WJbj3LvrDKpk13PjhT5uYLY9NYm7gjJXD9v6DXFTLFYEj0woBKNDgT+SIeoRcZMjVej84lpSKOysXJEq3RtKnkCLPDjtWtW7NBse/9ymwpMN0E6n8yYnXU+1rIxsfDKQWmohB2XPvd6rqKgdoh/rsUQnLDJfPoM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745222890; c=relaxed/simple; bh=JZ0kZKdRbiNdQAa6vM8J60QC56VS/GfpnaoTS0JJFw0=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=PVw6xzQRPUY8lFHN89VekU+ejJXjONX1jFJWZuzf3xqnuVwgwLacjztYeb3GHcHMYjMArE9lpwSx6we/wF1pu+eesMMk/7ztm6cbwjceCyHXxaRNaP+T2JfPmYoU8HRDB+XOlHwWznswNiIpfaDuW/xAqFFQfdJ8OGD10srQZF8= 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=QGhc5Vqk; arc=none smtp.client-ip=95.215.58.181 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="QGhc5Vqk" 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=1745222873; 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=p8NQ7PVzqMu7KcaRhcBhYFD/nldZYFbhOuQH3QcQRJg=; b=QGhc5VqklCLmb1cUQMjBZgPNFZeno8cV8ZTBkVaFlbmAy4D9CSuuOmKs/FxDO4HUSiL3Ni 1M7sv0T414DZuGBBTY0hTj8MW8DaY0jHnBpCBYbpgxUV/5j8x4g9H4BsPxkGa/tUz1YqNS 4ZRRhCNB4B4oTsrPWJchDd8JYPZ2K3Q= 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 v2] tools/mm: Add script to display page state for a given PID and VADDR Date: Mon, 21 Apr 2025 16:07:48 +0800 Message-Id: <20250421080748.114750-1-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 0x7f2c7de4c000 PID : 1 Comm : systemd mm : 0xffff888116b6d440 User Virtual Address : 0x7f2c7de4c000 Page Address : 0xffffea000b3a4000 raw: 0017ffffc000416c ffffea00045d1b08 ffffea000456d408 ffff888104521970 raw: 0000000000000000 ffff8881083fdb60 0000006900000018 ffff888107a41000 Page Flags : PG_referenced|PG_uptodate|PG_lru|PG_head|PG_active| PG_private|PG_reported Page Size : 16384 Page PFN : 0x2ce900 Page Physical : 0x2ce900000 Page Virtual : 0xffff8882ce900000 Page Refcount : 105 Page Mapcount : 24 Page Index : 0x0 Page Memcg Data : 0xffff888107a41000 Memcg Name : init.scope Memcg Path : /sys/fs/cgroup/memory/init.scope Page Mapping : 0xffff888104521970 Page Anon/File : File Page VMA : 0xffff888109e135e8 VMA Start : 0x7f2c7de4c000 VMA End : 0x7f2c7de58000 This page is part of a compound page. This page is the head page of a compound page. Head Page : 0xffffea000b3a4000 Compound Order : 2 Number of Pages : 4 Signed-off-by: Ye Liu 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 | 114 +++++++++++++++++++++++++++++++++++++ 2 files changed, 119 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..e3cccc4743be --- /dev/null +++ b/tools/mm/show_page_info.py @@ -0,0 +1,114 @@ +#!/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(f'User Virtual Address : {hex(addr)}') + print(f'Page Address : {hex(page.value_())}') + + print(format_page_data(prog.read(page.value_(), 64))) + + print(f'Page Flags : {decode_page_flags(page)}') + print(f'Page Size : {page_size(page).value_()}') + print(f'Page PFN : {hex(page_to_pfn(page).value_())}') + print(f'Page Physical : {hex(page_to_phys(page).value_())}') + print(f'Page Virtual : {hex(page_to_virt(page).value_())}') + print(f'Page Refcount : {page._refcount.counter.value_()}') + print(f'Page Mapcount : {page._mapcount.counter.value_()}') + print(f'Page Index : {hex(page.index.value_())}') + print(f'Page Memcg Data : {hex(page.memcg_data.value_())}') + + memcg_name, memcg_path =3D get_memcg_info(page) + print(f'Memcg Name : {memcg_name}') + print(f'Memcg Path : {memcg_path}') + + print(f'Page Mapping : {hex(page.mapping.value_())}') + print(f'Page Anon/File : {"Anon" if page.mapping.value_() & 0x1 else = "File"}') + + vma =3D vma_find(mm, addr) + print(f'Page VMA : {hex(vma.value_())}') + print(f'VMA Start : {hex(vma.vm_start.value_())}') + print(f'VMA End : {hex(vma.vm_end.value_())}') + + 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 : {hex(compound_head(page).value_())}') + print(f'Compound Order : {compound_order(page).value_()}') + print(f'Number of Pages : {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() + --=20 2.25.1