[PATCH v2 0/3] tools/mm/page_owner_sort: fix --sort, add module filter, improve usage

[Ye Liu <ye.liu@linux.dev>]

From: Ye Liu <liuye@kylinos.cn>

This series improves the page_owner_sort tool with a bug fix, a new
module-name feature, and better usage text.

Patch 1 fixes a long-standing bug where --sort was silently ignored
when used without a short option (-a, -m, -p, etc.).  The COMP_NO_FLAG
case fell through to COMP_NUM and overwrote the sort conditions
configured by parse_sort_args().

Patch 2 adds kernel module name support for sort, cull, and filter
operations.  Page owner stack traces already contain module names in
the "function+0xNN/0xNN [module]" format produced by %pS, but
page_owner_sort had no way to use them.  Records without module frames
are assigned "vmlinux".

  # Aggregate page usage per module
  ./page_owner_sort input.txt output.txt --cull=mod

  # Filter to records from xfs module only
  ./page_owner_sort input.txt output.txt --module xfs

  # Sort by module name, then by pid descending
  ./page_owner_sort input.txt output.txt --sort=mod,-pid

Patch 3 lists all available sort keys with abbreviations and examples
directly in the --sort help section so users no longer need to read
the source to discover valid keys.

Ye Liu (3):
  tools/mm/page_owner_sort: fix --sort option being silently ignored
  tools/mm/page_owner_sort: add module name sort/cull/filter support
  tools/mm/page_owner_sort: show available sort keys in usage text

 Documentation/mm/page_owner.rst |   8 +-
 tools/mm/page_owner_sort.c      | 135 +++++++++++++++++++++++++++-----
 2 files changed, 123 insertions(+), 20 deletions(-)
---
v2:
 - Patch 2: use regexec() directly in get_module() instead of search_pattern()
   to avoid excessive debug spam for the common vmlinux case when debug_on is true
 - Patch 2: anchor module regex to stack trace format "+0xNN/0xNN [module]" to
   prevent false matches on kernel thread comm names like [khugepaged]
 - Patch 2: add '-' to regex character class to support modules with hyphens
   (e.g. aa-bb-cc)
 - Link:https://lore.kernel.org/all/20260722023726.600200-1-ye.liu@linux.dev/

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2.25.1