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authorCliff Wickman <cpw@sgi.com>2007-09-24 21:24:41 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-25 08:51:04 -0700
commitafa684f6fda6086b229348f0ea21df7c8ad17964 (patch)
tree2a7c1fb54b6383af854a19f2545ad49abb3dc64a /drivers/char
parentf9b7cba1b8a74c10b0771ca28d4c554aeb9803fc (diff)
downloadop-kernel-dev-afa684f6fda6086b229348f0ea21df7c8ad17964.zip
op-kernel-dev-afa684f6fda6086b229348f0ea21df7c8ad17964.tar.gz
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: Cliff Wickman <cpw@sgi.com> Cc: Jes Sorensen <jes@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/mspec.c26
1 files changed, 8 insertions, 18 deletions
diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c
index 049a46cc9..04ac155 100644
--- a/drivers/char/mspec.c
+++ b/drivers/char/mspec.c
@@ -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
*
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