linux-kernel - Re: [PATCH v3] tools/mm: Add script to display page state for a given PID and VADDR

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Message-ID: <ba37651b-95fd-4db2-8806-58cd2a08a979@linux.dev>
Date: Thu, 24 Apr 2025 10:17:59 +0800
From: Ye Liu <ye.liu@...ux.dev>
To: Florian Weimer <fweimer@...hat.com>
Cc: akpm@...ux-foundation.org, linux-debuggers@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-toolchains@...r.kernel.org, osandov@...ndov.com, paulmck@...nel.org,
 sweettea-kernel@...miny.me, liuye@...inos.cn
Subject: Re: [PATCH v3] tools/mm: Add script to display page state for a given
 PID and VADDR


在 2025/4/23 17:45, Florian Weimer 写道:
> * Ye Liu:
>
>> From: Ye Liu <liuye@...inos.cn>
>>
>> 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
> Does this show the page access flags anywhere in the output?  If not,
> would it be possible to include this information?


This script is currently a basic version, and we plan to gradually add
more detailed information about pages, including the page access flags
you mentioned, as well as PGD, PUD, PMD, PTE, file/anon rmap folios,
and more. This will be refined over time.                             

Thanks,
Ye Liu

> Thanks,
> Florian
>