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]> --- arch/x86/mm/hugetlbpage.c | 64 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 61 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c index 42982b2..4f53af5 100644 --- a/arch/x86/mm/hugetlbpage.c +++ b/arch/x86/mm/hugetlbpage.c @@ -78,14 +78,39 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file, { 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; info.flags = 0; info.length = len; info.low_limit = current->mm->mmap_legacy_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; } static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file, @@ -95,16 +120,38 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file, struct hstate *h = hstate_file(file); struct vm_unmapped_area_info info; unsigned long addr; + bool pud_size_align = false; + + /* + * 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) && + !addr0 && flags & MAP_SHARED && len >= PUD_SIZE) + pud_size_align = true; info.flags = VM_UNMAPPED_AREA_TOPDOWN; info.length = len; info.low_limit = PAGE_SIZE; info.high_limit = current->mm->mmap_base; - 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; addr = vm_unmapped_area(&info); /* + * If failed with PUD_SIZE alignment, try again with huge page + * size alignment. + */ + if ((addr & ~PAGE_MASK) && pud_size_align) { + info.align_mask = PAGE_MASK & ~huge_page_mask(h); + addr = vm_unmapped_area(&info); + } + + /* * A failed mmap() very likely causes application failure, * so fall back to the bottom-up function here. This scenario * can happen with large stack limits and large mmap() @@ -115,7 +162,18 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file, info.flags = 0; info.low_limit = TASK_UNMAPPED_BASE; info.high_limit = TASK_SIZE; + if (pud_size_align) + info.align_mask = PAGE_MASK & (PUD_SIZE - 1); addr = vm_unmapped_area(&info); + + /* + * If failed again with PUD_SIZE alignment, finally try with + * huge page size alignment. + */ + if (addr & ~PAGE_MASK) { + info.align_mask = PAGE_MASK & ~huge_page_mask(h); + addr = vm_unmapped_area(&info); + } } return addr; -- 2.4.3
