From 9423117f846397d74e0ecae3a8f4bf31a6bfee39 Mon Sep 17 00:00:00 2001
From: Hari Bathini <hbathini@linux.vnet.ibm.com>
Date: Tue, 10 Apr 2018 19:11:31 +0530
Subject: [PATCH 2/2] powerpc/fadump: Do not use hugepages when fadump is
active
References: bsc#1092772
Patch-mainline: v4.18-rc1
Git-commit: 8597538712ebd90bc83dfb0b3b40398a0c53ad5b
FADump capture kernel boots in restricted memory environment preserving
the context of previous kernel to save vmcore. Supporting hugepages in
such environment makes things unnecessarily complicated, as hugepages
need memory set aside for them. This means most of the capture kernel's
memory is used in supporting hugepages. In most cases, this results in
out-of-memory issues while booting FADump capture kernel. But hugepages
are not of much use in capture kernel whose only job is to save vmcore.
So, disabling hugepages support, when fadump is active, is a reliable
solution for the out of memory issues. Introducing a flag variable to
disable HugeTLB support when fadump is active.
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/include/asm/page.h | 1 +
arch/powerpc/kernel/fadump.c | 8 ++++++++
arch/powerpc/mm/hash_utils_64.c | 6 ++++--
arch/powerpc/mm/hugetlbpage.c | 7 +++++++
4 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 8da5d4c1cab2..40aee9396556 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -39,6 +39,7 @@
#ifndef __ASSEMBLY__
#ifdef CONFIG_HUGETLB_PAGE
+extern bool hugetlb_disabled;
extern unsigned int HPAGE_SHIFT;
#else
#define HPAGE_SHIFT PAGE_SHIFT
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 3912ee481e9b..a17de8194488 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -395,6 +395,14 @@ int __init fadump_reserve_mem(void)
if (fw_dump.dump_active) {
pr_info("Firmware-assisted dump is active.\n");
+#ifdef CONFIG_HUGETLB_PAGE
+ /*
+ * FADump capture kernel doesn't care much about hugepages.
+ * In fact, handling hugepages in capture kernel is asking for
+ * trouble. So, disable HugeTLB support when fadump is active.
+ */
+ hugetlb_disabled = true;
+#endif
/*
* If last boot has crashed then reserve all the memory
* above boot_memory_size so that we don't touch it until
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 370f5561fff6..bb12ca52c0d7 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -570,8 +570,10 @@ static void __init htab_scan_page_sizes(void)
}
#ifdef CONFIG_HUGETLB_PAGE
- /* Reserve 16G huge page memory sections for huge pages */
- of_scan_flat_dt(htab_dt_scan_hugepage_blocks, NULL);
+ if (!hugetlb_disabled) {
+ /* Reserve 16G huge page memory sections for huge pages */
+ of_scan_flat_dt(htab_dt_scan_hugepage_blocks, NULL);
+ }
#endif /* CONFIG_HUGETLB_PAGE */
}
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 58ca476f2314..3df35127aacc 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -31,6 +31,8 @@
#define PAGE_SHIFT_16M 24
#define PAGE_SHIFT_16G 34
+bool hugetlb_disabled = false;
+
unsigned int HPAGE_SHIFT;
/*
@@ -805,6 +807,11 @@ static int __init hugetlbpage_init(void)
{
int psize;
+ if (hugetlb_disabled) {
+ pr_info("HugeTLB support is disabled!\n");
+ return 0;
+ }
+
#if !defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_PPC_8xx)
if (!radix_enabled() && !mmu_has_feature(MMU_FTR_16M_PAGE))
return -ENODEV;
--
2.13.6