From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-186.mta1.migadu.com (out-186.mta1.migadu.com [95.215.58.186]) (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 CF24F2741D2; Tue, 15 Apr 2025 07:51:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.186 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744703470; cv=none; b=PsoI1x7zmAefvLrnImTqtWN7JWShehpaICSeBBBuMqZkbvdLhwLYH3nUERABwvYSf7hf8UzPpjW+B1V9Q/QBDCM14XT7S6/6P0s8vnqqqGow9IW/RFq4JKK4zYR+Pk2OlSdq8oXPROdH5cWAPDIkKRlVeyrFbkQUk7V1twUZ504= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744703470; c=relaxed/simple; bh=r9ufPwUAMeRhf6lPmmzB6FeQNWgHbJaijd5wxqyPBhc=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=oS71kZxmYi4kbFfULMvCKEjkV9eJby0v+sLwJl5ZTpOj4cW0CBJ+tE8Le5aFAgChxPExS7kuHbcHk2z7qv4lkLBQH13BcnByk4KSXZF+zJQuiiMQkmndtVRJgbDomFMzQ3/mP8BwdPUEjcYZ4d378oU7RD2j/1Db9ey/hT0qbnw= 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=VVW72aPb; arc=none smtp.client-ip=95.215.58.186 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="VVW72aPb" 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=1744703465; 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=w7xWxJYFP6M/TEqfUiLVEiOQ7IdW+X8eIqI/gwRpLkM=; b=VVW72aPbTA5CfCPTg6YTyuwMbCkhi0MPTaIJpFSfD/e5VFBXH8gixxFCKrqH7KikTn/Nbi ziz5Dbj5TKBjMJhReTN66se8zEtDRf27BtfbIfM3gjLxnw3Vllh6EBXzDIsbZYjsQYoTfA 3eFlHnTcnES5z1l2eJPJmHy/6VB8O4A= From: Ye Liu To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: linux-toolchains@vger.kernel.org, linux-mm@kvack.org, Ye Liu Subject: [PATCH] tools/drgn: Add script to display page state for a given PID and VADDR Date: Tue, 15 Apr 2025 15:50:24 +0800 Message-Id: <20250415075024.248232-1-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-toolchains@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 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. Currently, there is no specific maintainer entry for `tools/drgn/` in the MAINTAINERS file. Therefore, this patch is sent to the general kernel and tools mailing lists for review. 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 --- tools/drgn/show_page_info.py | 120 +++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 tools/drgn/show_page_info.py diff --git a/tools/drgn/show_page_info.py b/tools/drgn/show_page_info.py new file mode 100644 index 000000000000..70d0cd97c7f0 --- /dev/null +++ b/tools/drgn/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_order, compound_nr +) +from drgn.helpers.linux.cgroup import cgroup_name, cgroup_path + +DESC = """ +This is a drgn script to show the page state. +For more info on drgn, visit https://github.com/osandov/drgn. +""" + +MEMCG_DATA_OBJEXTS = 1 << 0 +MEMCG_DATA_KMEM = 1 << 1 +__NR_MEMCG_DATA_FLAGS = 1 << 2 + +def format_page_data(data): + """Format raw page data into a readable hex dump.""" + chunks = [data[i:i+8] for i in range(0, len(data), 8)] + hex_chunks = ["".join(f"{b:02x}" for b in chunk[::-1]) for chunk in chunks] + lines = [" ".join(hex_chunks[i:i+4]) for i in range(0, len(hex_chunks), 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 = page.memcg_data.value_() + if memcg_data & MEMCG_DATA_OBJEXTS: + memcg_value = 0 + elif memcg_data & MEMCG_DATA_KMEM: + objcg = Object(prog, "struct obj_cgroup *", address=memcg_data & ~__NR_MEMCG_DATA_FLAGS) + memcg_value = objcg.memcg.value_() + else: + memcg_value = memcg_data & ~__NR_MEMCG_DATA_FLAGS + + memcg = Object(prog, "struct mem_cgroup *", address=memcg_value) + cgrp = 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'==============================================================') + 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(f'--------------------------------------------------------------') + + print(format_page_data(prog.read(page.value_(), 64))) + print(f'--------------------------------------------------------------') + + 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 = get_memcg_info(page) + print(f'Memcg Name : {memcg_name}') + print(f'Memcg Path : {memcg_path}') + print(f'--------------------------------------------------------------') + + print(f'Page Mapping : {hex(page.mapping.value_())}') + print(f'Page Anon/File : {"Anon" if page.mapping.value_() & 0x1 else "File"}') + + vma = 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_())}') + print(f'--------------------------------------------------------------') + + 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.") + print(f'==============================================================') + +def main(): + """Main function to parse arguments and display page state.""" + parser = argparse.ArgumentParser(description=DESC, formatter_class=argparse.RawTextHelpFormatter) + parser.add_argument('pid', metavar='PID', type=int, help='Target process ID (PID)') + parser.add_argument('vaddr', metavar='VADDR', type=str, help='Target virtual address in hexadecimal format (e.g., 0x7fff1234abcd)') + args = parser.parse_args() + + try: + vaddr = int(args.vaddr, 16) + except ValueError: + print(f"Error: Invalid virtual address format: {args.vaddr}") + return + + task = find_task(args.pid) + mm = task.mm + page = 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__ == "__main__": + main() + -- 2.25.1