[RFC PATCH v3 3/8] mm: restrict slub, compaction, and page_alloc to sysram

[Gregory Price <gourry@gourry.net>]

Restrict page allocation and zone iteration to N_MEMORY nodes via
cpusets - or node_states[N_MEMORY] when cpusets is disabled.

__GFP_THISNODE allows N_PRIVATE nodes to be used explicitly (all
nodes become valid targets with __GFP_THISNODE).

This constrains core users of nodemasks to the node_states[N_MEMORY],
which is guaranteed to at least contain the set of nodes with sysram
memory blocks present at boot.

Signed-off-by: Gregory Price <gourry@gourry.net>
---
 include/linux/gfp.h |  6 ++++++
 mm/compaction.c     |  6 ++----
 mm/page_alloc.c     | 27 ++++++++++++++++-----------
 mm/slub.c           |  8 ++++++--
 4 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index b155929af5b1..0b6cdef7a232 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -321,6 +321,7 @@ struct folio *folio_alloc_mpol_noprof(gfp_t gfp, unsigned int order,
 		struct mempolicy *mpol, pgoff_t ilx, int nid);
 struct folio *vma_alloc_folio_noprof(gfp_t gfp, int order, struct vm_area_struct *vma,
 		unsigned long addr);
+bool numa_zone_allowed(int alloc_flags, struct zone *zone, gfp_t gfp_mask);
 #else
 static inline struct page *alloc_pages_noprof(gfp_t gfp_mask, unsigned int order)
 {
@@ -337,6 +338,11 @@ static inline struct folio *folio_alloc_mpol_noprof(gfp_t gfp, unsigned int orde
 }
 #define vma_alloc_folio_noprof(gfp, order, vma, addr)		\
 	folio_alloc_noprof(gfp, order)
+static inline bool numa_zone_allowed(int alloc_flags, struct zone *zone,
+				     gfp_t gfp_mask)
+{
+	return true;
+}
 #endif
 
 #define alloc_pages(...)			alloc_hooks(alloc_pages_noprof(__VA_ARGS__))
diff --git a/mm/compaction.c b/mm/compaction.c
index 1e8f8eca318c..63ef9803607f 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2829,10 +2829,8 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
 					ac->highest_zoneidx, ac->nodemask) {
 		enum compact_result status;
 
-		if (cpusets_enabled() &&
-			(alloc_flags & ALLOC_CPUSET) &&
-			!__cpuset_zone_allowed(zone, gfp_mask))
-				continue;
+		if (!numa_zone_allowed(alloc_flags, zone, gfp_mask))
+			continue;
 
 		if (prio > MIN_COMPACT_PRIORITY
 					&& compaction_deferred(zone, order)) {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bb89d81aa68c..76b12cef7dfc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3723,6 +3723,16 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
 	return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
 				node_reclaim_distance;
 }
+bool numa_zone_allowed(int alloc_flags, struct zone *zone, gfp_t gfp_mask)
+{
+	/* If cpusets is being used, check mems_allowed or sysram_nodes */
+	if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET))
+		return cpuset_zone_allowed(zone, gfp_mask);
+
+	/* Otherwise only allow N_PRIVATE if __GFP_THISNODE is present */
+	return (gfp_mask & __GFP_THISNODE) ||
+		node_isset(zone_to_nid(zone), node_states[N_MEMORY]);
+}
 #else	/* CONFIG_NUMA */
 static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
 {
@@ -3814,10 +3824,9 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
 		struct page *page;
 		unsigned long mark;
 
-		if (cpusets_enabled() &&
-			(alloc_flags & ALLOC_CPUSET) &&
-			!__cpuset_zone_allowed(zone, gfp_mask))
-				continue;
+		if (!numa_zone_allowed(alloc_flags, zone, gfp_mask))
+			continue;
+
 		/*
 		 * When allocating a page cache page for writing, we
 		 * want to get it from a node that is within its dirty
@@ -4618,10 +4627,8 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
 		unsigned long min_wmark = min_wmark_pages(zone);
 		bool wmark;
 
-		if (cpusets_enabled() &&
-			(alloc_flags & ALLOC_CPUSET) &&
-			!__cpuset_zone_allowed(zone, gfp_mask))
-				continue;
+		if (!numa_zone_allowed(alloc_flags, zone, gfp_mask))
+			continue;
 
 		available = reclaimable = zone_reclaimable_pages(zone);
 		available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
@@ -5131,10 +5138,8 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
 	for_next_zone_zonelist_nodemask(zone, z, ac.highest_zoneidx, ac.nodemask) {
 		unsigned long mark;
 
-		if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) &&
-		    !__cpuset_zone_allowed(zone, gfp)) {
+		if (!numa_zone_allowed(alloc_flags, zone, gfp))
 			continue;
-		}
 
 		if (nr_online_nodes > 1 && zone != zonelist_zone(ac.preferred_zoneref) &&
 		    zone_to_nid(zone) != zonelist_node_idx(ac.preferred_zoneref)) {
diff --git a/mm/slub.c b/mm/slub.c
index 861592ac5425..adebbddc48f6 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3594,9 +3594,13 @@ static struct slab *get_any_partial(struct kmem_cache *s,
 			struct kmem_cache_node *n;
 
 			n = get_node(s, zone_to_nid(zone));
+			if (!n)
+				continue;
+
+			if (!numa_zone_allowed(ALLOC_CPUSET, zone, pc->flags))
+				continue;
 
-			if (n && cpuset_zone_allowed(zone, pc->flags) &&
-					n->nr_partial > s->min_partial) {
+			if (n->nr_partial > s->min_partial) {
 				slab = get_partial_node(s, n, pc);
 				if (slab) {
 					/*
-- 
2.52.0