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Commit afa684f6 authored by Cliff Wickman's avatar Cliff Wickman Committed by Linus Torvalds
Browse files

fix "mspec: handle shrinking virtual memory areas" 



The vma_data structure may be shared by vma's from multiple tasks, with no
way of knowing which areas are shared or not shared, so release/clear pages
only when the refcount (of vma's) goes to zero.

Signed-off-by: default avatarCliff Wickman <cpw@sgi.com>
Cc: Jes Sorensen <jes@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f9b7cba1

drivers/char/mspec.c

+8 −18
Original line number Diff line number Diff line
@@ -155,23 +155,22 @@ mspec_open(struct vm_area_struct *vma) 
 * mspec_close

 *

 * Called when unmapping a device mapping. Frees all mspec pages

 * belonging to the vma.

 * belonging to all the vma's sharing this vma_data structure.

 */

static void

mspec_close(struct vm_area_struct *vma)

{

	struct vma_data *vdata;

	int index, last_index, result;

	int index, last_index;

	unsigned long my_page;



	vdata = vma->vm_private_data;



	BUG_ON(vma->vm_start < vdata->vm_start || vma->vm_end > vdata->vm_end);

	if (!atomic_dec_and_test(&vdata->refcnt))

		return;



	spin_lock(&vdata->lock);

	index = (vma->vm_start - vdata->vm_start) >> PAGE_SHIFT;

	last_index = (vma->vm_end - vdata->vm_start) >> PAGE_SHIFT;

	for (; index < last_index; index++) {

	last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;

	for (index = 0; index < last_index; index++) {

		if (vdata->maddr[index] == 0)

			continue;

		/*
@@ -180,20 +179,12 @@ mspec_close(struct vm_area_struct *vma) 
		 */

		my_page = vdata->maddr[index];

		vdata->maddr[index] = 0;

		spin_unlock(&vdata->lock);

		result = mspec_zero_block(my_page, PAGE_SIZE);

		if (!result)

		if (!mspec_zero_block(my_page, PAGE_SIZE))

			uncached_free_page(my_page);

		else

			printk(KERN_WARNING "mspec_close(): "

			       "failed to zero page %i\n",

			       result);

		spin_lock(&vdata->lock);

			       "failed to zero page %ld\n", my_page);

	}

	spin_unlock(&vdata->lock);



	if (!atomic_dec_and_test(&vdata->refcnt))

		return;



	if (vdata->flags & VMD_VMALLOCED)

		vfree(vdata);
@@ -201,7 +192,6 @@ mspec_close(struct vm_area_struct *vma) 
		kfree(vdata);

}





/*

 * mspec_nopfn

 *