Patch "mm, thp: really limit transparent hugepage allocation to local node" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

mm, thp: really limit transparent hugepage allocation to local node

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mm-thp-really-limit-transparent-hugepage-allocation-to-local-node.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: David Rientjes <[email protected]>
Date: Tue, 14 Apr 2015 15:46:58 -0700
Subject: mm, thp: really limit transparent hugepage allocation to local node

From: David Rientjes <[email protected]>

commit 5265047ac30191ea24b16503165000c225f54feb upstream.

Commit 077fcf116c8c ("mm/thp: allocate transparent hugepages on local node") restructured alloc_hugepage_vma() with the intent of only allocating transparent hugepages locally when there was not an effective interleave mempolicy.

alloc_pages_exact_node() does not limit the allocation to the single node, however, but rather prefers it. This is because __GFP_THISNODE is not set which would cause the node-local nodemask to be passed. Without it, only a nodemask that prefers the local node is passed.

Fix this by passing __GFP_THISNODE and falling back to small pages when the allocation fails.

Commit 9f1b868a13ac ("mm: thp: khugepaged: add policy for finding target node") suffers from a similar problem for khugepaged, which is also fixed.

---
 mm/huge_memory.c |    9 +++++++--
 mm/mempolicy.c   |    3 ++-
 2 files changed, 9 insertions(+), 3 deletions(-)

@@ -2316,8 +2316,14 @@ static struct page
 		       struct vm_area_struct *vma, unsigned long address,
 		       int node)
 {
+	gfp_t flags;
+
 	VM_BUG_ON_PAGE(*hpage, *hpage);
 
+	/* Only allocate from the target node */
+	flags = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
+	        __GFP_THISNODE;
+
 	/*
 	 * Before allocating the hugepage, release the mmap_sem read lock.
 	 * The allocation can take potentially a long time if it involves

@@ -2326,8 +2332,7 @@ static struct page
 	 */
 	up_read(&mm->mmap_sem);
 
-	*hpage = alloc_pages_exact_node(node, alloc_hugepage_gfpmask(
-		khugepaged_defrag(), __GFP_OTHER_NODE), HPAGE_PMD_ORDER);
+	*hpage = alloc_pages_exact_node(node, flags, HPAGE_PMD_ORDER);
 	if (unlikely(!*hpage)) {
 		count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
 		*hpage = ERR_PTR(-ENOMEM);

@@ -1985,7 +1985,8 @@ retry_cpuset:
 		nmask = policy_nodemask(gfp, pol);
 		if (!nmask || node_isset(node, *nmask)) {
 			mpol_cond_put(pol);
-			page = alloc_pages_exact_node(node, gfp, order);
+			page = alloc_pages_exact_node(node,
+						gfp | __GFP_THISNODE, order);
 			goto out;
 		}
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/mm-hugetlb-use-pmd_page-in-follow_huge_pmd.patch queue-4.0/mm-thp-really-limit-transparent-hugepage-allocation-to-local-node.patch