On Wed, Jul 18, 2018 at 10:34:19AM -0400, Pavel Tatashin wrote:
> On Wed, Jul 18, 2018 at 8:47 AM <osalvador@xxxxxxxxxxxxxxxxxx> wrote:
> >
> > From: Oscar Salvador <osalvador@xxxxxxx>
> >
> > If free_area_init_node gets called from memhotplug code,
> > we do not need to call calculate_node_totalpages(),
> > as the node has no pages.
>
> I am not positive this is safe. Some pgdat fields in
> calculate_node_totalpages() are set. Even if those fields are always
> set to zeros, pgdat may be reused (i.e. node went offline and later
> came back online), so we might still need to set those fields to
> zeroes.
>
You are right, I do not know why, but I thought that we were zeroing pgdat struct
before getting in the function.
I will leave that part out.
Since we only should care about deferred pfns during the boot, maybe we can change
it to something like:
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 70fe4c80643f..89fc8f4240ca 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6381,6 +6381,21 @@ static void __ref alloc_node_mem_map(struct pglist_data *pgdat)
static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
#endif /* CONFIG_FLAT_NODE_MEM_MAP */
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+static 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
+static void pgdat_set_deferred_range(pg_data_t *pgdat) {}
+#endif
+
void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
unsigned long node_start_pfn, unsigned long *zholes_size)
{
@@ -6402,20 +6417,14 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
#else
start_pfn = node_start_pfn;
#endif
- calculate_node_totalpages(pgdat, start_pfn, end_pfn,
- zones_size, zholes_size);
+ calculate_node_totalpages(pgdat, start_pfn, end_pfn,
+ zones_size, zholes_size);
alloc_node_mem_map(pgdat);
-#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
- /*
- * 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;
-#endif
+ if (system_state == SYSTEM_BOOTING)
+ pgdat_set_deferred_range(pgdat);
+
free_area_init_core(pgdat);
}
Thanks
--
Oscar Salvador
SUSE L3
