Could someone please review this?
From: Wei Yang <richard.weiyang@xxxxxxxxx>
Subject: mm: check nr_initialised with PAGES_PER_SECTION directly in defer_init()
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@xxxxxxxxx
Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 2 --
mm/page_alloc.c | 13 ++++++-------
2 files changed, 6 insertions(+), 9 deletions(-)
--- a/include/linux/mmzone.h~mm-check-nr_initialised-with-pages_per_section-directly-in-defer_init
+++ a/include/linux/mmzone.h
@@ -692,8 +692,6 @@ typedef struct pglist_data {
* is the first PFN that needs to be initialised.
*/
unsigned long first_deferred_pfn;
- /* Number of non-deferred pages */
- unsigned long static_init_pgcnt;
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
--- a/mm/page_alloc.c~mm-check-nr_initialised-with-pages_per_section-directly-in-defer_init
+++ a/mm/page_alloc.c
@@ -326,8 +326,13 @@ defer_init(int nid, unsigned long pfn, u
/* Always populate low zones for address-constrained allocations */
if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
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++;
- if ((nr_initialised > NODE_DATA(nid)->static_init_pgcnt) &&
+ if ((nr_initialised > PAGES_PER_SECTION) &&
(pfn & (PAGES_PER_SECTION - 1)) == 0) {
NODE_DATA(nid)->first_deferred_pfn = pfn;
return true;
@@ -6585,12 +6590,6 @@ static void __ref alloc_node_mem_map(str
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
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;
}
#else
_
