When creating a hugetlb mapping, attempt PUD_SIZE alignment if the following conditions are met: - Address passed to mmap or shmat is NULL - The mapping is flaged as shared - The mapping is at least PUD_SIZE in length If a PUD_SIZE aligned mapping can not be created, then fall back to a huge page size mapping.
Signed-off-by: Mike Kravetz <[email protected]> --- fs/hugetlbfs/inode.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 540ddc9..22b2e38 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -175,6 +175,17 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, struct vm_area_struct *vma; struct hstate *h = hstate_file(file); struct vm_unmapped_area_info info; + bool pud_size_align = false; + unsigned long ret_addr; + + /* + * If PMD sharing is enabled, align to PUD_SIZE to facilitate + * sharing. Only attempt alignment if no address was passed in, + * flags indicate sharing and size is big enough. + */ + if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) && + !addr && flags & MAP_SHARED && len >= PUD_SIZE) + pud_size_align = true; if (len & ~huge_page_mask(h)) return -EINVAL; @@ -199,9 +210,23 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, info.length = len; info.low_limit = TASK_UNMAPPED_BASE; info.high_limit = TASK_SIZE; - info.align_mask = PAGE_MASK & ~huge_page_mask(h); + if (pud_size_align) + info.align_mask = PAGE_MASK & (PUD_SIZE - 1); + else + info.align_mask = PAGE_MASK & ~huge_page_mask(h); info.align_offset = 0; - return vm_unmapped_area(&info); + ret_addr = vm_unmapped_area(&info); + + /* + * If failed with PUD_SIZE alignment, try again with huge page + * size alignment. + */ + if ((ret_addr & ~PAGE_MASK) && pud_size_align) { + info.align_mask = PAGE_MASK & ~huge_page_mask(h); + ret_addr = vm_unmapped_area(&info); + } + + return ret_addr; } #endif -- 2.4.3
