[PATCHv6 01/22] mm: implement zero_huge_user_segment and friends
From: Kirill A. Shutemov <hidden>
Date: 2013-09-23 12:06:24
Also in:
linux-fsdevel, lkml
Subsystem:
memory management, memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Let's add helpers to clear huge page segment(s). They provide the same functionallity as zero_user_segment and zero_user, but for huge pages. Signed-off-by: Kirill A. Shutemov <redacted> --- include/linux/mm.h | 18 ++++++++++++++++++ mm/memory.c | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 54 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8b6e55ee88..a7b7e62930 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -1809,9 +1809,27 @@ extern void dump_page(struct page *page); extern void clear_huge_page(struct page *page, unsigned long addr, unsigned int pages_per_huge_page); +extern void zero_huge_user_segment(struct page *page, + unsigned start, unsigned end); +static inline void zero_huge_user(struct page *page, + unsigned start, unsigned len) +{ + zero_huge_user_segment(page, start, start + len); +} extern void copy_user_huge_page(struct page *dst, struct page *src, unsigned long addr, struct vm_area_struct *vma, unsigned int pages_per_huge_page); +#else +static inline void zero_huge_user_segment(struct page *page, + unsigned start, unsigned end) +{ + BUILD_BUG(); +} +static inline void zero_huge_user(struct page *page, + unsigned start, unsigned len) +{ + BUILD_BUG(); +} #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ #ifdef CONFIG_DEBUG_PAGEALLOC
diff --git a/mm/memory.c b/mm/memory.c
index ca00039471..e5f74cd634 100644
--- a/mm/memory.c
+++ b/mm/memory.c@@ -4291,6 +4291,42 @@ void clear_huge_page(struct page *page, } } +void zero_huge_user_segment(struct page *page, unsigned start, unsigned end) +{ + int i; + unsigned start_idx, end_idx; + unsigned start_off, end_off; + + BUG_ON(end < start); + + might_sleep(); + + if (start == end) + return; + + start_idx = start >> PAGE_SHIFT; + start_off = start & ~PAGE_MASK; + end_idx = (end - 1) >> PAGE_SHIFT; + end_off = ((end - 1) & ~PAGE_MASK) + 1; + + /* + * if start and end are on the same small page we can call + * zero_user_segment() once and save one kmap_atomic(). + */ + if (start_idx == end_idx) + return zero_user_segment(page + start_idx, start_off, end_off); + + /* zero the first (possibly partial) page */ + zero_user_segment(page + start_idx, start_off, PAGE_SIZE); + for (i = start_idx + 1; i < end_idx; i++) { + cond_resched(); + clear_highpage(page + i); + flush_dcache_page(page + i); + } + /* zero the last (possibly partial) page */ + zero_user_segment(page + end_idx, 0, end_off); +} + static void copy_user_gigantic_page(struct page *dst, struct page *src, unsigned long addr, struct vm_area_struct *vma,
--
1.8.4.rc3
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