a patch from the multi gen lru patch series author (yu zhao) to fix some
problems i saw on armv7l and some compile problems i saw on aarch64 with
CONFIG_CC_OPTIMIZE_FOR_SIZE enabled

"Thanks for the report. Please try the attached patch -- it should fix both of the problems.

We routinely test the MGLRU patchset on both 32-bit and 64-bit ARM CPUs. Our configs and compiler are different. 

    The build error smells like a gcc bug. It doesn't happen with clang.
    The crash on 32-bit happens when CONFIG_PGTABLE_LEVELS=2. Mine is unfortunately set to 3.

Please feel free to let me know if there is anything else I can do to help."


diff --git a/mm/Kconfig b/mm/Kconfig
index 05291697055a..e2e0be0d2e33 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -915,6 +915,7 @@ config LRU_GEN
 	depends on MMU
 	# make sure folio->flags has enough spare bits
 	depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP
+	default y
 	help
 	  A high performance LRU implementation to overcommit memory. See
 	  Documentation/admin-guide/mm/multigen_lru.rst for details.
@@ -922,6 +923,7 @@ config LRU_GEN
 config LRU_GEN_ENABLED
 	bool "Enable by default"
 	depends on LRU_GEN
+	default y
 	help
 	  This option enables the multi-gen LRU by default.
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 479cf221b59d..fe0c6475a6b4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2993,8 +2993,10 @@ static bool can_age_anon_pages(struct pglist_data *pgdat,
 
 #ifdef CONFIG_LRU_GEN_ENABLED
 DEFINE_STATIC_KEY_ARRAY_TRUE(lru_gen_caps, NR_LRU_GEN_CAPS);
+#define get_cap(cap)	static_branch_likely(&lru_gen_caps[cap])
 #else
 DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS);
+#define get_cap(cap)	static_branch_unlikely(&lru_gen_caps[cap])
 #endif
 
 /******************************************************************************
@@ -3017,15 +3019,6 @@ DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS);
 		for ((type) = 0; (type) < ANON_AND_FILE; (type)++)	\
 			for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++)
 
-static bool get_cap(int cap)
-{
-#ifdef CONFIG_LRU_GEN_ENABLED
-	return static_branch_likely(&lru_gen_caps[cap]);
-#else
-	return static_branch_unlikely(&lru_gen_caps[cap]);
-#endif
-}
-
 static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid)
 {
 	struct pglist_data *pgdat = NODE_DATA(nid);
@@ -4442,7 +4435,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
 		return;
 
 	start = max(pvmw->address & PMD_MASK, pvmw->vma->vm_start);
-	end = pmd_addr_end(pvmw->address, pvmw->vma->vm_end);
+	end = min(pvmw->address | ~PMD_MASK, pvmw->vma->vm_end - 1) + 1;
 
 	if (end - start > MIN_LRU_BATCH * PAGE_SIZE) {
 		if (pvmw->address - start < MIN_LRU_BATCH * PAGE_SIZE / 2)