[0/3] debug_pagealloc improvements

Message

Vlastimil Babka June 3, 2019, 2:34 p.m. UTC

I have been recently debugging some pcplist corruptions, where it would be
useful to perform struct page checks immediately as pages are allocated from
and freed to pcplists, which is now only possible by rebuilding the kernel with
CONFIG_DEBUG_VM (details in Patch 2 changelog).

To make this kind of debugging simpler in future on a distro kernel, I have
improved CONFIG_DEBUG_PAGEALLOC so that it has even smaller overhead when not
enabled at boot time (Patch 1) and also when enabled (Patch 3), and extended it
to perform the struct page checks more often when enabled (Patch 2). Now it can
be configured in when building a distro kernel without extra overhead, and
debugging page use after free or double free can be enabled simply by rebooting
with debug_pagealloc=on.

Vlastimil Babka (3):
  mm, debug_pagelloc: use static keys to enable debugging
  mm, page_alloc: more extensive free page checking with debug_pagealloc
  mm, debug_pagealloc: use a page type instead of page_ext flag

 .../admin-guide/kernel-parameters.txt         |  10 +-
 include/linux/mm.h                            |  25 ++--
 include/linux/page-flags.h                    |   6 +
 include/linux/page_ext.h                      |   1 -
 mm/Kconfig.debug                              |  14 ++-
 mm/page_alloc.c                               | 114 ++++++++++--------
 mm/page_ext.c                                 |   3 -
 7 files changed, 96 insertions(+), 77 deletions(-)