From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e6.ny.us.ibm.com (e6.ny.us.ibm.com [32.97.182.146]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e6.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id C84E3DDE08 for ; Thu, 8 Nov 2007 06:51:47 +1100 (EST) Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e6.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id lA7JrLZY028479 for ; Wed, 7 Nov 2007 14:53:21 -0500 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id lA7JpiHe110634 for ; Wed, 7 Nov 2007 14:51:44 -0500 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id lA7JpipV000380 for ; Wed, 7 Nov 2007 14:51:44 -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 Message-Id: <20071107195142.13505.49398.stgit@kernel> Content-Type: text/plain; charset=utf-8; format=fixed Cc: linuxppc-dev@ozlabs.org, Hoang-Nam Nguyen , Ken Chen , linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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; }