From: David Mosberger <davidm@napali.hpl.hp.com>,
"Sharma, Arun" <arun.sharma@intel.com>
The truncate race fix assumed that a non-zero vma->vm_ops->nopage implies a
non-zero vma->vm_file.
The ia64 x86 emulation code breaks this assumption, so teach do_no_page() to
handle it.
mm/memory.c | 13 ++++++++-----
1 files changed, 8 insertions(+), 5 deletions(-)
diff -puN mm/memory.c~nopage-fix mm/memory.c
--- 25/mm/memory.c~nopage-fix 2003-08-26 02:24:53.000000000 -0700
+++ 25-akpm/mm/memory.c 2003-08-26 02:25:00.000000000 -0700
@@ -1385,10 +1385,10 @@ do_no_page(struct mm_struct *mm, struct
unsigned long address, int write_access, pte_t *page_table, pmd_t *pmd)
{
struct page * new_page;
- struct address_space *mapping;
+ struct address_space *mapping = NULL;
pte_t entry;
struct pte_chain *pte_chain;
- int sequence;
+ int sequence = 0;
int ret;
if (!vma->vm_ops || !vma->vm_ops->nopage)
@@ -1397,8 +1397,10 @@ do_no_page(struct mm_struct *mm, struct
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
- mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
- sequence = atomic_read(&mapping->truncate_count);
+ if (vma->vm_file) {
+ mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
+ sequence = atomic_read(&mapping->truncate_count);
+ }
smp_rmb(); /* Prevent CPU from reordering lock-free ->nopage() */
retry:
new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, 0);
@@ -1434,7 +1436,8 @@ retry:
* invalidated this page. If invalidate_mmap_range got called,
* retry getting the page.
*/
- if (unlikely(sequence != atomic_read(&mapping->truncate_count))) {
+ if (mapping &&
+ (unlikely(sequence != atomic_read(&mapping->truncate_count)))) {
sequence = atomic_read(&mapping->truncate_count);
spin_unlock(&mm->page_table_lock);
page_cache_release(new_page);
_