[merged] mm-mempolicy-ignore-a-bind-policy-whose-nodes-have-no-memory.patch removed from -mm tree

[merged] mm-mempolicy-ignore-a-bind-policy-whose-nodes-have-no-memory.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/mempolicy: ignore a bind policy whose nodes have no memory
has been removed from the -mm tree.  Its filename was
     mm-mempolicy-ignore-a-bind-policy-whose-nodes-have-no-memory.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: "Gregory Price (Meta)" <gourry@gourry.net>
Subject: mm/mempolicy: ignore a bind policy whose nodes have no memory
Date: Fri, 13 Nov 2026 14:26:42 -0500

apply_policy_zone() assumes that policy->nodes intersects N_MEMORY, so
it reads a bind policy with no N_HIGH_MEMORY node as movable-only.

On systems with CONFIG_CPUSETS=n, nothing rebinds policies when memory
is removed, so offlining all memory on the nodes a bind policy names
leaves it with none. The policy is then treated as movable-only, and
movable allocations are restricted to nodes without memory.

This results in allocations failures, a VM_FAULT_OOM leak, and then
an infinitely retrying fault that hangs the process.

  page allocation failure: order:0, mode:0x140dca ... nodemask=2
  Huh VM_FAULT_OOM leaked out to the #PF handler. Retrying PF

Ignore a bind policy whose nodes have no memory. policy_nodemask()
already ignores a bind policy that does not intersect the cpuset.
This covers hugetlb's policy_mbind_nodemask() as well.

If the nodes regain memory, the policy applies again.

CPUSETS=n with HOTREMOVE=y is unlikely a common configuration, so this
isn't marked for stable.

Link: https://lore.kernel.org/20261113192642.2618878-1-gourry@gourry.net
Signed-off-by: Gregory Price (Meta) <gourry@gourry.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: SJ Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
---

 mm/mempolicy.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/mm/mempolicy.c~mm-mempolicy-ignore-a-bind-policy-whose-nodes-have-no-memory
+++ a/mm/mempolicy.c
@@ -2100,6 +2100,10 @@ bool apply_policy_zone(struct mempolicy
 
 	BUG_ON(dynamic_policy_zone == ZONE_MOVABLE);
 
+	/* Memory hot-remove can leave policy->nodes without memory. */
+	if (!nodes_intersects(policy->nodes, node_states[N_MEMORY]))
+		return false;
+
 	/*
 	 * if policy->nodes has movable memory only,
 	 * we apply policy when gfp_zone(gfp) = ZONE_MOVABLE only.
_

Patches currently in -mm which might be from gourry@gourry.net are

mm-memory-tiers-reset-demotion-targets-of-nodes-without-memory.patch
mm-mempolicy-convert-mempolicy-refcnt-to-refcount_t.patch
selftests-mm-add-madv_cold-and-madv_pageout-contract-tests.patch
selftests-mm-check-madv_cold-and-madv_pageout-range-handling.patch
selftests-mm-check-that-madv_cold-and-madv_pageout-reject-hugetlb.patch
selftests-mm-check-that-madv_cold-and-madv_pageout-preserve-shared-memory.patch
selftests-mm-check-madv_cold-and-madv_pageout-on-partly-advised-thps.patch
selftests-mm-check-madv_pageout-file-permissions.patch
selftests-mm-check-that-unauthorized-madv_pageout-skips-large-file-folios.patch
mm-hmm-reject-shadow-stack-mappings.patch