Currently we take naive approach to page flags on compound -- we set the flag on the page without consideration if the flag makes sense for tail page or for compound page in general. This patchset try to sort this out by defining per-flag policy on what need to be done if page-flag helper operate on compound page. The last patch in patchset also sanitize usege of page->mapping for tail pages. We don't define meaning of page->mapping for tail pages. Currently it's always NULL, which can be inconsistent with head page and potentially lead to problems. For now I catched one case of illigal usage of page flags or ->mapping: sound subsystem allocates pages with __GFP_COMP and maps them with PTEs. It leads to setting dirty bit on tail pages and access to tail_page's ->mapping. I don't see any bad behaviour caused by this, but worth fixing anyway. This patchset makes more sense if you take my THP refcounting into account: we will see more compound pages mapped with PTEs and we need to define behaviour of flags on compound pages to avoid bugs. Kirill A. Shutemov (16): mm: consolidate all page-flags helpers in <linux/page-flags.h> page-flags: trivial cleanup for PageTrans* helpers page-flags: introduce page flags policies wrt compound pages page-flags: define PG_locked behavior on compound pages page-flags: define behavior of FS/IO-related flags on compound pages page-flags: define behavior of LRU-related flags on compound pages page-flags: define behavior SL*B-related flags on compound pages page-flags: define behavior of Xen-related flags on compound pages page-flags: define PG_reserved behavior on compound pages page-flags: define PG_swapbacked behavior on compound pages page-flags: define PG_swapcache behavior on compound pages page-flags: define PG_mlocked behavior on compound pages page-flags: define PG_uncached behavior on compound pages page-flags: define PG_uptodate behavior on compound pages page-flags: look on head page if the flag is encoded in page->mapping mm: sanitize page->mapping for tail pages fs/cifs/file.c | 8 +- include/linux/hugetlb.h | 7 - include/linux/ksm.h | 17 --- include/linux/mm.h | 122 +---------------- include/linux/page-flags.h | 317 ++++++++++++++++++++++++++++++++++----------- include/linux/pagemap.h | 25 ++-- include/linux/poison.h | 4 + mm/filemap.c | 15 ++- mm/huge_memory.c | 2 +- mm/ksm.c | 2 +- mm/memory-failure.c | 2 +- mm/memory.c | 2 +- mm/migrate.c | 2 +- mm/page_alloc.c | 7 + mm/shmem.c | 4 +- mm/slub.c | 2 + mm/swap_state.c | 4 +- mm/util.c | 5 +- mm/vmscan.c | 4 +- mm/zswap.c | 4 +- 20 files changed, 294 insertions(+), 261 deletions(-) -- 2.1.4 -- 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>