When we debug something, we'd like to insert some information to every page. For this purpose, we sometimes modify struct page itself. But, this has drawbacks. First, it requires re-compile. This makes us hesitate to use the powerful debug feature so development process is slowed down. And, second, sometimes it is impossible to rebuild the kernel due to third party module dependency. At third, system behaviour would be largely different after re-compile, because it changes size of struct page greatly and this structure is accessed by every part of kernel. Keeping this as it is would be better to reproduce errornous situation. To overcome these drawbacks, we can extend struct page on another place rather than struct page itself. Until now, memcg uses this technique. But, now, memcg decides to embed their variable to struct page itself and it's code to extend struct page has been removed. I'd like to use this code to develop debug feature, so this series resurrect it. With resurrecting it, this patchset makes two debugging features boottime configurable. As mentioned above, rebuild has serious problems. Making it boottime configurable mitigate these problems with marginal computational overhead. One of the features, page_owner isn't in mainline now. But, it is really useful so it is in mm tree for a long time. I think that it's time to upstream this feature. Any comments are more than welcome. This patchset is based on next-20141106 + my two patches related to debug-pagealloc [1]. [1]: https://lkml.org/lkml/2014/11/7/78 Joonsoo Kim (5): mm/page_ext: resurrect struct page extending code for debugging mm/debug-pagealloc: prepare boottime configurable on/off mm/debug-pagealloc: make debug-pagealloc boottime configurable stacktrace: support snprint mm/page_owner: keep track of page owners arch/powerpc/mm/hash_utils_64.c | 2 +- arch/powerpc/mm/pgtable_32.c | 2 +- arch/s390/mm/pageattr.c | 2 +- arch/sparc/mm/init_64.c | 2 +- arch/x86/mm/pageattr.c | 2 +- include/linux/mm.h | 35 +++- include/linux/mm_types.h | 4 - include/linux/mmzone.h | 12 ++ include/linux/page-debug-flags.h | 32 ---- include/linux/page_ext.h | 84 +++++++++ include/linux/page_owner.h | 19 +++ include/linux/stacktrace.h | 3 + init/main.c | 7 + kernel/stacktrace.c | 24 +++ lib/Kconfig.debug | 13 ++ mm/Kconfig.debug | 10 ++ mm/Makefile | 2 + mm/debug-pagealloc.c | 31 +++- mm/page_alloc.c | 61 ++++++- mm/page_ext.c | 346 ++++++++++++++++++++++++++++++++++++++ mm/page_owner.c | 206 +++++++++++++++++++++++ mm/vmstat.c | 93 ++++++++++ tools/vm/Makefile | 4 +- tools/vm/page_owner_sort.c | 144 ++++++++++++++++ 24 files changed, 1087 insertions(+), 53 deletions(-) delete mode 100644 include/linux/page-debug-flags.h create mode 100644 include/linux/page_ext.h create mode 100644 include/linux/page_owner.h create mode 100644 mm/page_ext.c create mode 100644 mm/page_owner.c create mode 100644 tools/vm/page_owner_sort.c -- 1.7.9.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>