Reported-by: Alex Williamson <redacted>
Signed-off-by: Andrea Arcangeli <redacted>
---
 include/linux/gfp.h | 18 ++++++++++++++++++
 mm/mempolicy.c      | 12 +++++++++++-
 mm/page_alloc.c     |  4 ++++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index a6afcec53795..3c04d5d90e6d 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h

@@ -44,6 +44,7 @@ struct vm_area_struct;
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
+#define ___GFP_ONLY_COMPACT	0x1000000u
 /* If the above are modified, __GFP_BITS_SHIFT may need updating */

 /*

@@ -178,6 +179,21 @@ struct vm_area_struct;
  *   definitely preferable to use the flag rather than opencode endless
  *   loop around allocator.
  *   Using this flag for costly allocations is _highly_ discouraged.
+ *
+ * __GFP_ONLY_COMPACT: Only invoke compaction. Do not try to succeed
+ * the allocation by freeing memory. Never risk to free any
+ * "PAGE_SIZE" memory unit even if compaction failed specifically
+ * because of not enough free pages in the zone. This only makes sense
+ * only in combination with __GFP_THISNODE (enforced with a
+ * VM_WARN_ON), to restrict the THP allocation in the local node that
+ * triggered the page fault and fallback into PAGE_SIZE allocations in
+ * the same node. We don't want to invoke reclaim because there may be
+ * plenty of free memory already in the local node. More importantly
+ * there may be even plenty of free THP available in remote nodes so
+ * we should allocate those if something instead of reclaiming any
+ * memory in the local node. Implementation detail: set ___GFP_NORETRY
+ * too so that ___GFP_ONLY_COMPACT only needs to be checked in a slow
+ * path.
  */
 #define __GFP_IO	((__force gfp_t)___GFP_IO)
 #define __GFP_FS	((__force gfp_t)___GFP_FS)

@@ -187,6 +203,8 @@ struct vm_area_struct;
 #define __GFP_RETRY_MAYFAIL	((__force gfp_t)___GFP_RETRY_MAYFAIL)
 #define __GFP_NOFAIL	((__force gfp_t)___GFP_NOFAIL)
 #define __GFP_NORETRY	((__force gfp_t)___GFP_NORETRY)
+#define __GFP_ONLY_COMPACT	((__force gfp_t)(___GFP_NORETRY | \
+						 ___GFP_ONLY_COMPACT))

 /*
  * Action modifiers

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d6512ef28cde..6bf839f20dcc 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c

@@ -2047,8 +2047,18 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,

 		if (!nmask || node_isset(hpage_node, *nmask)) {
 			mpol_cond_put(pol);
+			/*
+			 * We restricted the allocation to the
+			 * hpage_node so we must use
+			 * __GFP_ONLY_COMPACT to allow at most a
+			 * compaction attempt and not ever get into
+			 * reclaim or it'll swap heavily with
+			 * transparent_hugepage/defrag = always (or
+			 * madvise under MADV_HUGEPAGE).
+			 */
 			page = __alloc_pages_node(hpage_node,
-						gfp | __GFP_THISNODE, order);
+						  gfp | __GFP_THISNODE |
+						  __GFP_ONLY_COMPACT, order);
 			goto out;
 		}
 	}

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a790ef4be74e..01a5c2bd0860 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c

@@ -4144,6 +4144,10 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 			 */
 			if (compact_result == COMPACT_DEFERRED)
 				goto nopage;
+			if (gfp_mask & __GFP_ONLY_COMPACT) {
+				VM_WARN_ON(!(gfp_mask & __GFP_THISNODE));
+				goto nopage;
+			}

 			/*
 			 * Looks like reclaim/compaction is worth trying, but