From 5e60b2ac289f62d046cb0f15bb3fd898347404e5 Mon Sep 17 00:00:00 2001
From: K Pamnany <kpamnany@users.noreply.github.com>
Date: Mon, 21 Aug 2023 12:19:17 -0400
Subject: [PATCH] RAI: Disable huge pages for all mmap'ed memory

Prevent transparent huge pages (THP) overallocating pysical memory.
---
 src/gc-pages.c  | 4 ++++
 src/gc-stacks.c | 3 +++
 src/gc.c        | 3 +++
 3 files changed, 10 insertions(+)

diff --git a/src/gc-pages.c b/src/gc-pages.c
index 856fabecaab98..ac6b6678fd4d8 100644
--- a/src/gc-pages.c
+++ b/src/gc-pages.c
@@ -74,6 +74,10 @@ static char *jl_gc_try_alloc_pages(int pg_cnt) JL_NOTSAFEPOINT
         return NULL;
     poolmem_bytes_allocated += pages_sz;
     poolmem_blocks_allocated_total++;
+
+#ifdef MADV_NOHUGEPAGE
+    madvise(mem, pages_sz, MADV_NOHUGEPAGE);
+#endif
 #endif
     if (GC_PAGE_SZ > jl_page_size)
         // round data pointer up to the nearest gc_page_data-aligned
diff --git a/src/gc-stacks.c b/src/gc-stacks.c
index b35c1722c82ff..4c477dd3d4c17 100644
--- a/src/gc-stacks.c
+++ b/src/gc-stacks.c
@@ -61,6 +61,9 @@ static void *malloc_stack(size_t bufsz) JL_NOTSAFEPOINT
         munmap(stk, bufsz);
         return MAP_FAILED;
     }
+#ifdef MADV_NOHUGEPAGE
+    madvise(stk, bufsz, MADV_NOHUGEPAGE);
+#endif
 #endif
     jl_atomic_fetch_add(&num_stack_mappings, 1);
     return stk;
diff --git a/src/gc.c b/src/gc.c
index e9e26bb748994..ea207bbab7698 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -4171,6 +4171,9 @@ void *jl_gc_perm_alloc_nolock(size_t sz, int zero, unsigned align, unsigned offs
     errno = last_errno;
     if (__unlikely(pool == MAP_FAILED))
         return NULL;
+#ifdef MADV_NOHUGEPAGE
+    madvise(pool, GC_PERM_POOL_SIZE, MADV_NOHUGEPAGE);
+#endif
 #endif
     gc_perm_pool = (uintptr_t)pool;
     gc_perm_end = gc_perm_pool + GC_PERM_POOL_SIZE;