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(-) -- 2.21.0
