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authorMatthew Wilcox <willy@linux.intel.com>2015-09-08 14:59:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-08 15:35:28 -0700
commit73a6ec47f68787df1b41869def52915da2f4a6b7 (patch)
treecbc6d973dbe88c0d397a62167bd5d3d66337ba40 /fs
parentd295e3415a88ae63a37a22652808b20c7fcb970e (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.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/dax.c b/fs/dax.c
index d778e5f1a01c..74838c43be91 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -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)) {

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