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| author |   Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2017-09-29 17:08:16 +0300 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2017-10-20 13:07:09 +0200 |
| commit | 83e3c48729d9ebb7af5a31a504f3fd6aff0348c4 (patch) | |
| tree | 9e42ac40f3bb837359325e0b247ec8e16c1c0b52 /include/linux/mmzone.h | |
| parent | Merge branch 'x86/urgent' into x86/mm, to pick up fixes (diff) | |
| download | linux-dev-83e3c48729d9ebb7af5a31a504f3fd6aff0348c4.tar.xz linux-dev-83e3c48729d9ebb7af5a31a504f3fd6aff0348c4.zip | |
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.h | 6 |
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]; |