Major Changes from v2 * patch 5: fix potential buffer overflow in snprint_stack_trace() return generated string length in snprint_stack_trace() * patch 6: disable in default, add enabling boot option * patch 8(new): documentation for page owner Major Changes from v1 * patch 1: add overall design description in code comment * patch 6: make page owner more accurate for alloc_pages_exact() and compaction/CMA * patch 7: handles early allocated pages for page owner 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 (8): 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 mm/nommu: use alloc_pages_exact() rather than it's own implementation stacktrace: introduce snprint_stack_trace for buffer output mm/page_owner: keep track of page owners mm/page_owner: correct owner information for early allocated pages Documentation: add new page_owner document Documentation/kernel-parameters.txt | 14 ++ Documentation/vm/page_owner.txt | 81 +++++++ 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 | 36 +++- 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 | 38 ++++ include/linux/stacktrace.h | 5 + init/main.c | 7 + kernel/stacktrace.c | 32 +++ lib/Kconfig.debug | 16 ++ mm/Kconfig.debug | 10 + mm/Makefile | 2 + mm/debug-pagealloc.c | 45 +++- mm/nommu.c | 33 +-- mm/page_alloc.c | 67 +++++- mm/page_ext.c | 394 +++++++++++++++++++++++++++++++++++ mm/page_owner.c | 311 +++++++++++++++++++++++++++ mm/vmstat.c | 101 +++++++++ tools/vm/Makefile | 4 +- tools/vm/page_owner_sort.c | 144 +++++++++++++ 27 files changed, 1406 insertions(+), 76 deletions(-) create mode 100644 Documentation/vm/page_owner.txt 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>