| Message ID | 20250415075024.248232-1-ye.liu@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tools/drgn: Add script to display page state for a given PID and VADDR | expand |
On Tue, 15 Apr 2025 15:50:24 +0800 Ye Liu <ye.liu@linux.dev> wrote: > From: Ye Liu <liuye@kylinos.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. > > 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. Help. My copy of linux has no tools/drgn/
在 2025/4/16 10:14, Andrew Morton 写道: > On Tue, 15 Apr 2025 15:50:24 +0800 Ye Liu <ye.liu@linux.dev> wrote: > >> From: Ye Liu <liuye@kylinos.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. >> >> 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. > Help. My copy of linux has no tools/drgn/ I noticed that the current upstream Linux tree doesn't contain a `tools/drgn/` directory. I'm interested in contributing a drgn script tool as well. Given that this directory does not yet exist in mainline, where would be the appropriate place to add new drgn scripts? Would it make sense to create a new `tools/drgn/` directory, or is there a preferred location for such debugging scripts? Thanks, Ye
On 4/15/25 10:46 PM, Ye Liu wrote: > > 在 2025/4/16 10:14, Andrew Morton 写道: >> On Tue, 15 Apr 2025 15:50:24 +0800 Ye Liu <ye.liu@linux.dev> wrote: >> >>> From: Ye Liu <liuye@kylinos.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. >>> >>> 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. >> Help. My copy of linux has no tools/drgn/ > I noticed that the current upstream Linux tree doesn't contain a > `tools/drgn/` directory. > > I'm interested in contributing a drgn script tool as well. > Given that this directory does not yet exist in mainline, where would > be the appropriate place to add new drgn scripts? Would it make sense > to create a new `tools/drgn/` directory, or is there a preferred > location for such debugging scripts? > > Thanks, > Ye I believe the traditional thing to do with new drgn scripts is to add them to the contrib directory in drgn via pull request: https://github.com/osandov/drgn/blob/main/contrib/README.rst
On Tue, Apr 15, 2025 at 11:28:41PM -0400, Sweet Tea Dorminy wrote: > > > On 4/15/25 10:46 PM, Ye Liu wrote: > > > > 在 2025/4/16 10:14, Andrew Morton 写道: > > > On Tue, 15 Apr 2025 15:50:24 +0800 Ye Liu <ye.liu@linux.dev> wrote: > > > > > > > From: Ye Liu <liuye@kylinos.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. > > > > > > > > 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. > > > Help. My copy of linux has no tools/drgn/ > > I noticed that the current upstream Linux tree doesn't contain a > > `tools/drgn/` directory. > > > > I'm interested in contributing a drgn script tool as well. > > Given that this directory does not yet exist in mainline, where would > > be the appropriate place to add new drgn scripts? Would it make sense > > to create a new `tools/drgn/` directory, or is there a preferred > > location for such debugging scripts? > > > > Thanks, > > Ye > > I believe the traditional thing to do with new drgn scripts is to add them > to the contrib directory in drgn via pull request: > https://github.com/osandov/drgn/blob/main/contrib/README.rst I have an RCU-related drgn script in tools/rcu, so maybe this one should go in tools/mm. Thanx, Paul
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 <liuye@kylinos.cn> + +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() +