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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2017-09-29 17:08:16 +0300
committerIngo Molnar <mingo@kernel.org>2017-10-20 14:07:09 +0300
commit83e3c48729d9ebb7af5a31a504f3fd6aff0348c4 (patch)
tree9e42ac40f3bb837359325e0b247ec8e16c1c0b52 /include/linux/mmzone.h
parent967535223f9a8d95c187a8728480b569164cd4f4 (diff)
downloadlinux-83e3c48729d9ebb7af5a31a504f3fd6aff0348c4.tar.xz
mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y
Size of the mem_section[] array depends on the size of the physical address space. In preparation for boot-time switching between paging modes on x86-64 we need to make the allocation of mem_section[] dynamic, because otherwise we waste a lot of RAM: with CONFIG_NODE_SHIFT=10, mem_section[] size is 32kB for 4-level paging and 2MB for 5-level paging mode. The patch allocates the array on the first call to sparse_memory_present_with_active_regions(). Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@suse.de> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170929140821.37654-2-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/mmzone.h')
-rw-r--r--include/linux/mmzone.h6
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index c8f89417740b..e796edf1296f 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1150,13 +1150,17 @@ struct mem_section {
#define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)
#ifdef CONFIG_SPARSEMEM_EXTREME
-extern struct mem_section *mem_section[NR_SECTION_ROOTS];
+extern struct mem_section **mem_section;
#else
extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
#endif
static inline struct mem_section *__nr_to_section(unsigned long nr)
{
+#ifdef CONFIG_SPARSEMEM_EXTREME
+ if (!mem_section)
+ return NULL;
+#endif
if (!mem_section[SECTION_NR_TO_ROOT(nr)])
return NULL;
return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];