diff options
| author | Matthew Wilcox | 2015-09-08 14:59:37 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2015-09-08 15:35:28 -0700 |
| commit | 73a6ec47f68787df1b41869def52915da2f4a6b7 (patch) | |
| tree | cbc6d973dbe88c0d397a62167bd5d3d66337ba40 /fs | |
| parent | d295e3415a88ae63a37a22652808b20c7fcb970e (diff) | |
dax: ensure that zero pages are removed from other processes
If the first access to a huge page was a store, there would be no existing
zero pmd in this process's page tables. There could be a zero pmd in
another process's page tables, if it had done a load. We can detect this
case by noticing that the buffer_head returned from the filesystem is New,
and ensure that other processes mapping this huge page have their page
tables flushed.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/dax.c | 6 |
1 files changed, 5 insertions, 1 deletions
@@ -568,7 +568,11 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if ((pgoff | PG_PMD_COLOUR) >= size) goto fallback; - if (is_huge_zero_pmd(*pmd)) + /* + * If we allocated new storage, make sure no process has any + * zero pages covering this hole + */ + if (buffer_new(&bh)) unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0); if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) { |