The patch titled
hugetlb: acquire the i_mmap_lock before walking the prio_tree to unmap a page
has been removed from the -mm tree. Its filename was
hugetlb-acquire-the-i_mmap_lock-before-walking-the-prio_tree-to-unmap-a-page-v2.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: hugetlb: acquire the i_mmap_lock before walking the prio_tree to unmap a page
From: Mel Gorman <mel@xxxxxxxxx>
When the owner of a mapping fails COW because a child process is holding a
reference, the children VMAs are walked and the page is unmapped. The
i_mmap_lock is taken for the unmapping of the page but not the walking of
the prio_tree. In theory, that tree could be changing if the lock is not
held. This patch takes the i_mmap_lock properly for the duration of the
prio_tree walk.
[hugh.dickins@xxxxxxxxxxxxx: Spotted the problem in the first place]
Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
Acked-by: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff -puN mm/hugetlb.c~hugetlb-acquire-the-i_mmap_lock-before-walking-the-prio_tree-to-unmap-a-page-v2 mm/hugetlb.c
--- a/mm/hugetlb.c~hugetlb-acquire-the-i_mmap_lock-before-walking-the-prio_tree-to-unmap-a-page-v2
+++ a/mm/hugetlb.c
@@ -2237,6 +2237,12 @@ static int unmap_ref_private(struct mm_s
+ (vma->vm_pgoff >> PAGE_SHIFT);
mapping = (struct address_space *)page_private(page);
+ /*
+ * Take the mapping lock for the duration of the table walk. As
+ * this mapping should be shared between all the VMAs,
+ * __unmap_hugepage_range() is called as the lock is already held
+ */
+ spin_lock(&mapping->i_mmap_lock);
vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
/* Do not unmap the current VMA */
if (iter_vma == vma)
@@ -2250,10 +2256,11 @@ static int unmap_ref_private(struct mm_s
* from the time of fork. This would look like data corruption
*/
if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
- unmap_hugepage_range(iter_vma,
+ __unmap_hugepage_range(iter_vma,
address, address + huge_page_size(h),
page);
}
+ spin_unlock(&mapping->i_mmap_lock);
return 1;
}
_
Patches currently in -mm which might be from mel@xxxxxxxxx are
origin.patch
mm-add-notifier-in-pageblock-isolation-for-balloon-drivers.patch
powerpc-make-the-cmm-memory-hotplug-aware.patch
powerpc-make-the-cmm-memory-hotplug-aware-update.patch
mm-warn-once-when-a-page-is-freed-with-pg_mlocked-set.patch
add-debugging-aid-for-memory-initialisation-problems.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
