linux-kernel - [PATCH v3 6/6] efi: Disable mirror feature if kernelcore is not specified

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Message-ID: <20220607093805.1354256-7-mawupeng1@huawei.com>
Date:   Tue, 7 Jun 2022 17:38:05 +0800
From:   Wupeng Ma <mawupeng1@...wei.com>
To:     <corbet@....net>, <will@...nel.org>, <ardb@...nel.org>,
        <catalin.marinas@....com>
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Subject: [PATCH v3 6/6] efi: Disable mirror feature if kernelcore is not specified

From: Ma Wupeng <mawupeng1@...wei.com>

If system have some mirrored memory and mirrored feature is not specified
in boot parameter, the basic mirrored feature will be enabled and this will
lead to the following situations:

- memblock memory allocation prefers mirrored region. This may have some
  unexpected influence on numa affinity.

- contiguous memory will be split into several parts if parts of them
  is mirrored memory via memblock_mark_mirror().

To fix this, variable mirrored_kernelcore will be checked before calling
efi_find_mirror() which will enable basic mirrored feature and this
variable is true if kernelcore=mirror is added in the kernel parameters.

Signed-off-by: Ma Wupeng <mawupeng1@...wei.com>
---
 drivers/firmware/efi/efi.c | 3 +++
 include/linux/mm.h         | 2 ++
 mm/page_alloc.c            | 2 +-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 79c232e07de7..8a5edcb0dd82 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -454,6 +454,9 @@ void __init efi_find_mirror(void)
 	if (!efi_enabled(EFI_MEMMAP))
 		return;
 
+	if (!mirrored_kernelcore)
+		return;
+
 	for_each_efi_memory_desc(md) {
 		unsigned long long start = md->phys_addr;
 		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bc8f326be0ce..741ac7d022c3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2540,6 +2540,8 @@ extern void get_pfn_range_for_nid(unsigned int nid,
 			unsigned long *start_pfn, unsigned long *end_pfn);
 extern unsigned long find_min_pfn_with_active_regions(void);
 
+extern bool mirrored_kernelcore;
+
 #ifndef CONFIG_NUMA
 static inline int early_pfn_to_nid(unsigned long pfn)
 {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e008a3df0485..cf6f70aba787 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -356,7 +356,7 @@ static unsigned long required_kernelcore_percent __initdata;
 static unsigned long required_movablecore __initdata;
 static unsigned long required_movablecore_percent __initdata;
 static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
-static bool mirrored_kernelcore __meminitdata;
+bool mirrored_kernelcore __meminitdata;
 
 /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
 int movable_zone;
-- 
2.25.1