Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756726AbXKGTv4 (ORCPT ); Wed, 7 Nov 2007 14:51:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754041AbXKGTvt (ORCPT ); Wed, 7 Nov 2007 14:51:49 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.146]:55136 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753969AbXKGTvs (ORCPT ); Wed, 7 Nov 2007 14:51:48 -0500 From: Adam Litke Subject: [PATCH] hugetlb: follow_hugetlb_page for write access Date: Wed, 07 Nov 2007 11:51:43 -0800 To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Hoang-Nam Nguyen , Ken Chen , Adam Litke Message-Id: <20071107195142.13505.49398.stgit@kernel> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit User-Agent: StGIT/0.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3254 Lines: 73 When calling get_user_pages(), a write flag is passed in by the caller to indicate if write access is required on the faulted-in pages. Currently, follow_hugetlb_page() ignores this flag and always faults pages for read-only access. This can cause data corruption because a device driver that calls get_user_pages() with write set will not expect COW faults to occur on the returned pages. This patch passes the write flag down to follow_hugetlb_page() and makes sure hugetlb_fault() is called with the right write_access parameter. Signed-off-by: Adam Litke --- include/linux/hugetlb.h | 2 +- mm/hugetlb.c | 5 +++-- mm/memory.c | 2 +- 3 files changed, 5 insertions(+), 4 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 3a19b03..31fa0a0 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -19,7 +19,7 @@ static inline int is_vm_hugetlb_page(struct vm_area_struct *vma) int hugetlb_sysctl_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *); int hugetlb_treat_movable_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *); int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *); -int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int); +int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int, int); void unmap_hugepage_range(struct vm_area_struct *, unsigned long, unsigned long); void __unmap_hugepage_range(struct vm_area_struct *, unsigned long, unsigned long); int hugetlb_prefault(struct address_space *, struct vm_area_struct *); diff --git a/mm/hugetlb.c b/mm/hugetlb.c index eab8c42..b645985 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -621,7 +621,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, struct page **pages, struct vm_area_struct **vmas, - unsigned long *position, int *length, int i) + unsigned long *position, int *length, int i, + int write) { unsigned long pfn_offset; unsigned long vaddr = *position; @@ -643,7 +644,7 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, int ret; spin_unlock(&mm->page_table_lock); - ret = hugetlb_fault(mm, vma, vaddr, 0); + ret = hugetlb_fault(mm, vma, vaddr, write); spin_lock(&mm->page_table_lock); if (!(ret & VM_FAULT_ERROR)) continue; diff --git a/mm/memory.c b/mm/memory.c index f82b359..1bcd444 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1039,7 +1039,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, if (is_vm_hugetlb_page(vma)) { i = follow_hugetlb_page(mm, vma, pages, vmas, - &start, &len, i); + &start, &len, i, write); continue; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/