path: root/mm
diff options
authorBaoquan He <bhe@redhat.com>2018-08-17 15:48:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-17 16:20:31 -0700
commitf2fc10e0b3fe7d1aecbd2cab6bf0007b6771e16d (patch)
tree54ba9725c59a875521f0982e7bf3579547f8a007 /mm
parent7e010df53c80197b23119e7d7b95892aa13629df (diff)
mm/sparse.c: add a static variable nr_present_sections
Patch series "mm/sparse: Optimize memmap allocation during sparse_init()", v6. In sparse_init(), two temporary pointer arrays, usemap_map and map_map are allocated with the size of NR_MEM_SECTIONS. They are used to store each memory section's usemap and mem map if marked as present. In 5-level paging mode, this will cost 512M memory though they will be released at the end of sparse_init(). System with few memory, like kdump kernel which usually only has about 256M, will fail to boot because of allocation failure if CONFIG_X86_5LEVEL=y. In this patchset, optimize the memmap allocation code to only use usemap_map and map_map with the size of nr_present_sections. This makes kdump kernel boot up with normal crashkernel='' setting when CONFIG_X86_5LEVEL=y. This patch (of 5): nr_present_sections is used to record how many memory sections are marked as present during system boot up, and will be used in the later patch. Link: http://lkml.kernel.org/r/20180228032657.32385-2-bhe@redhat.com Signed-off-by: Baoquan He <bhe@redhat.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Pankaj Gupta <pagupta@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/sparse.c b/mm/sparse.c
index b1b14a9c4041..99a6383e98bc 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -200,6 +200,12 @@ static inline int next_present_section_nr(int section_nr)
(section_nr <= __highest_present_section_nr)); \
section_nr = next_present_section_nr(section_nr))
+ * Record how many memory sections are marked as present
+ * during system bootup.
+ */
+static int __initdata nr_present_sections;
/* Record a memory area against a node. */
void __init memory_present(int nid, unsigned long start, unsigned long end)
@@ -229,6 +235,7 @@ void __init memory_present(int nid, unsigned long start, unsigned long end)
ms->section_mem_map = sparse_encode_early_nid(nid) |
+ nr_present_sections++;