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| author | Cliff Wickman <cpw@sgi.com> | 2007-09-24 21:24:41 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-09-25 08:51:04 -0700 |
| commit | afa684f6fda6086b229348f0ea21df7c8ad17964 (patch) | |
| tree | 2a7c1fb54b6383af854a19f2545ad49abb3dc64a /drivers/char/mspec.c | |
| parent | f9b7cba1b8a74c10b0771ca28d4c554aeb9803fc (diff) | |
| download | linux-stable-afa684f6fda6086b229348f0ea21df7c8ad17964.tar.gz linux-stable-afa684f6fda6086b229348f0ea21df7c8ad17964.tar.bz2 linux-stable-afa684f6fda6086b229348f0ea21df7c8ad17964.zip | |
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/mspec.c')
| -rw-r--r-- | drivers/char/mspec.c | 26 |
1 files changed, 8 insertions, 18 deletions
diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c index 049a46cc9f87..04ac155d3a07 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 * |