From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Sat, 15 Oct 2022 22:15:11 +0800
Subject: [PATCH] mm: Try invalidate disk caches last when out of memory

Every heap grow will cause all disk caches invalidated which decreases
performance severely. This patch moves disk cache invalidation code to
the last of memory squeezing measures. So, disk caches are released only
when there are no other ways to get free memory.

Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Patrick Steinhardt <ps@pks.im>
(cherry picked from commit 17975d10a80e2457e5237f87fa58a7943031983e)
---
 grub-core/kern/mm.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/grub-core/kern/mm.c b/grub-core/kern/mm.c
index f2e27f263b..da1ac9427c 100644
--- a/grub-core/kern/mm.c
+++ b/grub-core/kern/mm.c
@@ -443,12 +443,6 @@ grub_memalign (grub_size_t align, grub_size_t size)
   switch (count)
     {
     case 0:
-      /* Invalidate disk caches.  */
-      grub_disk_cache_invalidate_all ();
-      count++;
-      goto again;
-
-    case 1:
       /* Request additional pages, contiguous */
       count++;
 
@@ -458,7 +452,7 @@ grub_memalign (grub_size_t align, grub_size_t size)
 
       /* fallthrough  */
 
-    case 2:
+    case 1:
       /* Request additional pages, anything at all */
       count++;
 
@@ -474,6 +468,12 @@ grub_memalign (grub_size_t align, grub_size_t size)
 
       /* fallthrough */
 
+    case 2:
+      /* Invalidate disk caches.  */
+      grub_disk_cache_invalidate_all ();
+      count++;
+      goto again;
+
     default:
       break;
     }