linux-kernel - [RFC 20/43] PKRAM: disable feature when running the kdump kernel

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Date:   Wed,  6 May 2020 17:41:46 -0700
From:   Anthony Yznaga <anthony.yznaga@...cle.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     willy@...radead.org, corbet@....net, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
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Subject: [RFC 20/43] PKRAM: disable feature when running the kdump kernel

The kdump kernel should not preserve or restore pages.

Signed-off-by: Anthony Yznaga <anthony.yznaga@...cle.com>
---
 mm/pkram.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/pkram.c b/mm/pkram.c
index 95e691382721..4d4d836fea53 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <linux/crash_dump.h>
 #include <linux/err.h>
 #include <linux/gfp.h>
 #include <linux/highmem.h>
@@ -193,7 +194,7 @@ void __init pkram_reserve(void)
 {
 	int err = 0;
 
-	if (!pkram_sb_pfn)
+	if (!pkram_sb_pfn || is_kdump_kernel())
 		return;
 
 	pr_info("PKRAM: Examining preserved memory...\n");
@@ -305,6 +306,9 @@ static void pkram_show_banned(void)
 	int i;
 	unsigned long n, total = 0;
 
+	if (is_kdump_kernel())
+		return;
+
 	pr_info("PKRAM: banned regions:\n");
 	for (i = 0; i < nr_banned; i++) {
 		n = banned[i].end - banned[i].start + 1;
@@ -1223,7 +1227,7 @@ static int __init pkram_init_sb(void)
 
 static int __init pkram_init(void)
 {
-	if (pkram_init_sb()) {
+	if (!is_kdump_kernel() && pkram_init_sb()) {
 		register_reboot_notifier(&pkram_reboot_notifier);
 		register_shrinker(&banned_pages_shrinker);
 		sysfs_update_group(kernel_kobj, &pkram_attr_group);
-- 
2.13.3