On Fri, Jul 04, 2008 at 03:39:26AM -0400, Christoph Hellwig wrote:
I agree that zap_pages_range() is more general than what is needed.
How about the following. This should prevent abuse of the API &
provide what (I think) drivers need.
Verified with GRU & XPMEM.
--- jack
--------------------------------------------------------------------------------------------
Add function to unmap driver ptes.
zap_vma_ptes() is intended to be used by drivers to unmap
ptes assigned to the driver private vmas. This interface is
similar to zap_page_range() but is less general & less likely to
be abused.
Signed-off-by: Jack Steiner <steiner@sgi.com>
---
include/linux/mm.h | 2 ++
mm/memory.c | 23 +++++++++++++++++++++++
2 files changed, 25 insertions(+)
Index: linux/include/linux/mm.h
===================================================================
--- linux.orig/include/linux/mm.h 2008-07-07 12:22:17.809892803 -0500
+++ linux/include/linux/mm.h 2008-07-07 12:22:56.126695482 -0500
@@ -742,6 +742,8 @@ struct zap_details {
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
pte_t pte);
+int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
+ unsigned long size);
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *);
unsigned long unmap_vmas(struct mmu_gather **tlb,
Index: linux/mm/memory.c
===================================================================
--- linux.orig/mm/memory.c 2008-07-07 12:22:18.357961503 -0500
+++ linux/mm/memory.c 2008-07-07 12:31:51.097688882 -0500
@@ -978,6 +978,29 @@ unsigned long zap_page_range(struct vm_a
}
EXPORT_SYMBOL_GPL(zap_page_range);
+/**
+ * zap_vma_ptes - remove ptes mapping the vma
+ * @vma: vm_area_struct holding ptes to be zapped
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ *
+ * This function only unmaps ptes assigned to VM_PFNMAP vmas.
+ *
+ * The entire address range must be fully contained within the vma.
+ *
+ * Returns 0 if successful.
+ */
+int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
+ unsigned long size)
+{
+ if (address < vma->vm_start || address + size > vma->vm_end ||
+ !(vma->vm_flags & VM_PFNMAP))
+ return -1;
+ zap_page_range(vma, address, size, NULL);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(zap_vma_ptes);
+
/*
* Do a quick page-table lookup for a single page.
*/
--
