From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from digeo-nav01.digeo.com (digeo-nav01.digeo.com [192.168.1.233]) by packet.digeo.com (8.9.3+Sun/8.9.3) with SMTP id PAA05810 for ; Fri, 31 Jan 2003 15:14:48 -0800 (PST) Date: Fri, 31 Jan 2003 15:17:11 -0800 From: Andrew Morton Subject: Re: hugepage patches Message-Id: <20030131151711.7c8aaee7.akpm@digeo.com> In-Reply-To: <20030131151501.7273a9bf.akpm@digeo.com> References: <20030131151501.7273a9bf.akpm@digeo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: davem@redhat.com, rohit.seth@intel.com, davidm@napali.hpl.hp.com, anton@samba.org, wli@holomorphy.com, linux-mm@kvack.org List-ID: 2/4 ia32 and others can determine a page's hugeness by inspecting the pmd's value directly. No need to perform a VMA lookup against the user's virtual address. This patch ifdef's away the VMA-based implementation of hugepage-aware-follow_page for ia32 and replaces it with a pmd-based implementation. The intent is that architectures will implement one or the other. So the architecture either: 1: Implements hugepage_vma()/follow_huge_addr(), and stubs out pmd_huge()/follow_huge_pmd() or 2: Implements pmd_huge()/follow_huge_pmd(), and stubs out hugepage_vma()/follow_huge_addr() arch/i386/mm/hugetlbpage.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ include/asm-i386/pgtable.h | 5 +++++ include/linux/hugetlb.h | 3 +++ mm/memory.c | 6 +++++- 4 files changed, 58 insertions(+), 1 deletion(-) diff -puN mm/memory.c~pin_page-pmd mm/memory.c --- 25/mm/memory.c~pin_page-pmd Fri Jan 31 14:30:01 2003 +++ 25-akpm/mm/memory.c Fri Jan 31 14:30:01 2003 @@ -618,7 +618,11 @@ follow_page(struct mm_struct *mm, unsign goto out; pmd = pmd_offset(pgd, address); - if (pmd_none(*pmd) || pmd_bad(*pmd)) + if (pmd_none(*pmd)) + goto out; + if (pmd_huge(*pmd)) + return follow_huge_pmd(mm, address, pmd, write); + if (pmd_bad(*pmd)) goto out; ptep = pte_offset_map(pmd, address); diff -puN include/linux/hugetlb.h~pin_page-pmd include/linux/hugetlb.h --- 25/include/linux/hugetlb.h~pin_page-pmd Fri Jan 31 14:30:01 2003 +++ 25-akpm/include/linux/hugetlb.h Fri Jan 31 14:30:01 2003 @@ -24,6 +24,8 @@ struct page *follow_huge_addr(struct mm_ unsigned long address, int write); struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long address); +struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, + pmd_t *pmd, int write); extern int htlbpage_max; static inline void @@ -51,6 +53,7 @@ static inline int is_vm_hugetlb_page(str #define hugetlb_report_meminfo(buf) 0 #define hugepage_vma(mm, addr) 0 #define mark_mm_hugetlb(mm, vma) do { } while (0) +#define follow_huge_pmd(mm, addr, pmd, write) 0 #endif /* !CONFIG_HUGETLB_PAGE */ diff -puN include/asm-i386/pgtable.h~pin_page-pmd include/asm-i386/pgtable.h --- 25/include/asm-i386/pgtable.h~pin_page-pmd Fri Jan 31 14:30:01 2003 +++ 25-akpm/include/asm-i386/pgtable.h Fri Jan 31 14:30:01 2003 @@ -177,6 +177,11 @@ extern unsigned long pg0[1024]; #define pmd_clear(xp) do { set_pmd(xp, __pmd(0)); } while (0) #define pmd_bad(x) ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE) +#ifdef CONFIG_HUGETLB_PAGE +int pmd_huge(pmd_t pmd); +#else +#define pmd_huge(x) 0 +#endif #define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT)) diff -puN arch/i386/mm/hugetlbpage.c~pin_page-pmd arch/i386/mm/hugetlbpage.c --- 25/arch/i386/mm/hugetlbpage.c~pin_page-pmd Fri Jan 31 14:30:01 2003 +++ 25-akpm/arch/i386/mm/hugetlbpage.c Fri Jan 31 14:30:01 2003 @@ -150,6 +150,7 @@ back1: return i; } +#if 0 /* This is just for testing */ struct page * follow_huge_addr(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, int write) @@ -179,6 +180,50 @@ struct vm_area_struct *hugepage_vma(stru return NULL; } +int pmd_huge(pmd_t pmd) +{ + return 0; +} + +struct page * +follow_huge_pmd(struct mm_struct *mm, unsigned long address, + pmd_t *pmd, int write) +{ + return NULL; +} + +#else + +struct page * +follow_huge_addr(struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long address, int write) +{ + return NULL; +} + +struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr) +{ + return NULL; +} + +int pmd_huge(pmd_t pmd) +{ + return !!(pmd_val(pmd) & _PAGE_PSE); +} + +struct page * +follow_huge_pmd(struct mm_struct *mm, unsigned long address, + pmd_t *pmd, int write) +{ + struct page *page; + + page = pte_page(*(pte_t *)pmd); + if (page) + page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT); + return page; +} +#endif + void free_huge_page(struct page *page) { BUG_ON(page_count(page)); _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/