From: Song Liu <songliubraving@xxxxxx> Subject: mm: move memcmp_pages() and pages_identical() Patch series "THP aware uprobe", v13. This patchset makes uprobe aware of THPs. Currently, when uprobe is attached to text on THP, the page is split by FOLL_SPLIT. As a result, uprobe eliminates the performance benefit of THP. This set makes uprobe THP-aware. Instead of FOLL_SPLIT, we introduces FOLL_SPLIT_PMD, which only split PMD for uprobe. After all uprobes within the THP are removed, the PTE-mapped pages are regrouped as huge PMD. This set (plus a few THP patches) is also available at https://github.com/liu-song-6/linux/tree/uprobe-thp This patch (of 6): Move memcmp_pages() to mm/util.c and pages_identical() to mm.h, so that we can use them in other files. Link: http://lkml.kernel.org/r/20190815164525.1848545-2-songliubraving@xxxxxx Signed-off-by: Song Liu <songliubraving@xxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Matthew Wilcox <matthew.wilcox@xxxxxxxxxx> Cc: William Kucharski <william.kucharski@xxxxxxxxxx> Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm.h | 7 +++++++ mm/ksm.c | 18 ------------------ mm/util.c | 13 +++++++++++++ 3 files changed, 20 insertions(+), 18 deletions(-) --- a/include/linux/mm.h~mm-move-memcmp_pages-and-pages_identical +++ a/include/linux/mm.h @@ -2868,5 +2868,12 @@ void __init setup_nr_node_ids(void); static inline void setup_nr_node_ids(void) {} #endif +extern int memcmp_pages(struct page *page1, struct page *page2); + +static inline int pages_identical(struct page *page1, struct page *page2) +{ + return !memcmp_pages(page1, page2); +} + #endif /* __KERNEL__ */ #endif /* _LINUX_MM_H */ --- a/mm/ksm.c~mm-move-memcmp_pages-and-pages_identical +++ a/mm/ksm.c @@ -1029,24 +1029,6 @@ static u32 calc_checksum(struct page *pa return checksum; } -static int memcmp_pages(struct page *page1, struct page *page2) -{ - char *addr1, *addr2; - int ret; - - addr1 = kmap_atomic(page1); - addr2 = kmap_atomic(page2); - ret = memcmp(addr1, addr2, PAGE_SIZE); - kunmap_atomic(addr2); - kunmap_atomic(addr1); - return ret; -} - -static inline int pages_identical(struct page *page1, struct page *page2) -{ - return !memcmp_pages(page1, page2); -} - static int write_protect_page(struct vm_area_struct *vma, struct page *page, pte_t *orig_pte) { --- a/mm/util.c~mm-move-memcmp_pages-and-pages_identical +++ a/mm/util.c @@ -783,3 +783,16 @@ out_mm: out: return res; } + +int memcmp_pages(struct page *page1, struct page *page2) +{ + char *addr1, *addr2; + int ret; + + addr1 = kmap_atomic(page1); + addr2 = kmap_atomic(page2); + ret = memcmp(addr1, addr2, PAGE_SIZE); + kunmap_atomic(addr2); + kunmap_atomic(addr1); + return ret; +} _
