From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file

---
 kernel/mm/mm_init.c |   39 +++++++++++++++++++++++++++------------
 1 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/kernel/mm/mm_init.c b/kernel/mm/mm_init.c
index 6838a53..b06a30f 100644
--- a/kernel/mm/mm_init.c
+++ b/kernel/mm/mm_init.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * mm_init.c - Memory initialisation verification and debugging
  *
@@ -12,6 +13,7 @@
 #include <linux/memory.h>
 #include <linux/notifier.h>
 #include <linux/sched.h>
+#include <linux/mman.h>
 #include "internal.h"
 
 #ifdef CONFIG_DEBUG_MEMORY_INIT
@@ -36,7 +38,7 @@
 		struct zonelist *zonelist;
 		int i, listid, zoneid;
 
-		BUG_ON(MAX_ZONELISTS > 2);
+		BUILD_BUG_ON(MAX_ZONELISTS > 2);
 		for (i = 0; i < MAX_ZONELISTS * MAX_NR_ZONES; i++) {
 
 			/* Identify the zone and nodelist */
@@ -66,26 +68,30 @@
 	unsigned long or_mask, add_mask;
 
 	shift = 8 * sizeof(unsigned long);
-	width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH - LAST_CPUPID_SHIFT;
+	width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH
+		- LAST_CPUPID_SHIFT - KASAN_TAG_WIDTH;
 	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_widths",
-		"Section %d Node %d Zone %d Lastcpupid %d Flags %d\n",
+		"Section %d Node %d Zone %d Lastcpupid %d Kasantag %d Flags %d\n",
 		SECTIONS_WIDTH,
 		NODES_WIDTH,
 		ZONES_WIDTH,
 		LAST_CPUPID_WIDTH,
+		KASAN_TAG_WIDTH,
 		NR_PAGEFLAGS);
 	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts",
-		"Section %d Node %d Zone %d Lastcpupid %d\n",
+		"Section %d Node %d Zone %d Lastcpupid %d Kasantag %d\n",
 		SECTIONS_SHIFT,
 		NODES_SHIFT,
 		ZONES_SHIFT,
-		LAST_CPUPID_SHIFT);
+		LAST_CPUPID_SHIFT,
+		KASAN_TAG_WIDTH);
 	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_pgshifts",
-		"Section %lu Node %lu Zone %lu Lastcpupid %lu\n",
+		"Section %lu Node %lu Zone %lu Lastcpupid %lu Kasantag %lu\n",
 		(unsigned long)SECTIONS_PGSHIFT,
 		(unsigned long)NODES_PGSHIFT,
 		(unsigned long)ZONES_PGSHIFT,
-		(unsigned long)LAST_CPUPID_PGSHIFT);
+		(unsigned long)LAST_CPUPID_PGSHIFT,
+		(unsigned long)KASAN_TAG_PGSHIFT);
 	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_nodezoneid",
 		"Node/Zone ID: %lu -> %lu\n",
 		(unsigned long)(ZONEID_PGOFF + ZONEID_SHIFT),
@@ -139,14 +145,23 @@
 #ifdef CONFIG_SMP
 s32 vm_committed_as_batch = 32;
 
-static void __meminit mm_compute_batch(void)
+void mm_compute_batch(int overcommit_policy)
 {
 	u64 memsized_batch;
 	s32 nr = num_present_cpus();
 	s32 batch = max_t(s32, nr*2, 32);
+	unsigned long ram_pages = totalram_pages();
 
-	/* batch size set to 0.4% of (total memory/#cpus), or max int32 */
-	memsized_batch = min_t(u64, (totalram_pages/nr)/256, 0x7fffffff);
+	/*
+	 * For policy OVERCOMMIT_NEVER, set batch size to 0.4% of
+	 * (total memory/#cpus), and lift it to 25% for other policies
+	 * to easy the possible lock contention for percpu_counter
+	 * vm_committed_as, while the max limit is INT_MAX
+	 */
+	if (overcommit_policy == OVERCOMMIT_NEVER)
+		memsized_batch = min_t(u64, ram_pages/nr/256, INT_MAX);
+	else
+		memsized_batch = min_t(u64, ram_pages/nr/4, INT_MAX);
 
 	vm_committed_as_batch = max_t(s32, memsized_batch, batch);
 }
@@ -157,7 +172,7 @@
 	switch (action) {
 	case MEM_ONLINE:
 	case MEM_OFFLINE:
-		mm_compute_batch();
+		mm_compute_batch(sysctl_overcommit_memory);
 	default:
 		break;
 	}
@@ -171,7 +186,7 @@
 
 static int __init mm_compute_batch_init(void)
 {
-	mm_compute_batch();
+	mm_compute_batch(sysctl_overcommit_memory);
 	register_hotmemory_notifier(&compute_batch_nb);
 
 	return 0;

--
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