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mm: check nr_initialised with PAGES_PER_SECTION directly in defer_init()

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When DEFERRED_STRUCT_PAGE_INIT is configured, only the first section of
each node's highest zone is initialized before defer stage.

static_init_pgcnt is used to store the number of pages like this:

    pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
                                              pgdat->node_spanned_pages);

because we don't want to overflow zone's range.

But this is not necessary, since defer_init() is called like this:

  memmap_init_zone()
    for pfn in [start_pfn, end_pfn)
      defer_init(pfn, end_pfn)

In case (pgdat->node_spanned_pages < PAGES_PER_SECTION), the loop would
stop before calling defer_init().

BTW, comparing PAGES_PER_SECTION with node_spanned_pages is not correct,
since nr_initialised is zone based instead of node based.  Even
node_spanned_pages is bigger than PAGES_PER_SECTION, its highest zone
would have pages less than PAGES_PER_SECTION.

Link: http://lkml.kernel.org/r/20181122094807.6985-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Wei Yang 2018-12-28 00:36:18 -08:00 committed by Linus Torvalds
parent 9a1ea439b1
commit 23b68cfaae
2 changed files with 6 additions and 9 deletions
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2
include/linux/mmzone.h
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@ -692,8 +692,6 @@ typedef struct pglist_data {
* is the first PFN that needs to be initialised. * is the first PFN that needs to be initialised.
*/ */
unsigned long first_deferred_pfn; unsigned long first_deferred_pfn;
/* Number of non-deferred pages */
unsigned long static_init_pgcnt;
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */ #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
#ifdef CONFIG_TRANSPARENT_HUGEPAGE #ifdef CONFIG_TRANSPARENT_HUGEPAGE

13
mm/page_alloc.c
View File

@ -326,8 +326,13 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
/* Always populate low zones for address-constrained allocations */ /* Always populate low zones for address-constrained allocations */
if (end_pfn < pgdat_end_pfn(NODE_DATA(nid))) if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
return false; return false;
/*
* We start only with one section of pages, more pages are added as
* needed until the rest of deferred pages are initialized.
*/
nr_initialised++; nr_initialised++;
if ((nr_initialised > NODE_DATA(nid)->static_init_pgcnt) && if ((nr_initialised > PAGES_PER_SECTION) &&
(pfn & (PAGES_PER_SECTION - 1)) == 0) { (pfn & (PAGES_PER_SECTION - 1)) == 0) {
NODE_DATA(nid)->first_deferred_pfn = pfn; NODE_DATA(nid)->first_deferred_pfn = pfn;
return true; return true;
@ -6585,12 +6590,6 @@ static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static inline void pgdat_set_deferred_range(pg_data_t *pgdat) static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
{ {
/*
* We start only with one section of pages, more pages are added as
* needed until the rest of deferred pages are initialized.
*/
pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
pgdat->node_spanned_pages);
pgdat->first_deferred_pfn = ULONG_MAX; pgdat->first_deferred_pfn = ULONG_MAX;
} }
#else #else