On Sat, Mar 23, 2019 at 09:40:04AM +0500, Mikhail Gavrilov wrote:
> > /*
> > * Only clear the hint if a sample indicates there is either a
> > * free page or an LRU page in the block. One or other condition
> > * is necessary for the block to be a migration source/target.
> > */
> > - block_pfn = pageblock_start_pfn(pfn);
> > - pfn = max(block_pfn, zone->zone_start_pfn);
> > - page = pfn_to_page(pfn);
> > - if (zone != page_zone(page))
> > - return false;
> > - pfn = block_pfn + pageblock_nr_pages;
> > - pfn = min(pfn, zone_end_pfn(zone));
> > - end_page = pfn_to_page(pfn);
> > -
> > do {
> > if (pfn_valid_within(pfn)) {
> > if (check_source && PageLRU(page)) {
>
> Unfortunately this patch didn't helps too.
>
> kernel log: https://pastebin.com/RHhmXPM2
>
Ok, it's somewhat of a pity that we don't know what PFN that page
corresponds to. Specifically it would be interesting to know if the PFN
corresponds to a memory hole as DMA32 on your machine has a number of
gaps. What I'm wondering is if the reinit fails to find good starting
points that it picks a PFN that corresponds to an uninitialised page and
trips up later.
Can you try again with this patch please? It replaces the failed patch
entirely.
Thanks.
diff --git a/mm/compaction.c b/mm/compaction.c
index f171a83707ce..caac4b07eb33 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -242,6 +242,7 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source,
bool check_target)
{
struct page *page = pfn_to_online_page(pfn);
+ struct page *block_page;
struct page *end_page;
unsigned long block_pfn;
@@ -267,20 +268,26 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source,
get_pageblock_migratetype(page) != MIGRATE_MOVABLE)
return false;
+ /* Ensure the start of the pageblock or zone is online and valid */
+ block_pfn = pageblock_start_pfn(pfn);
+ block_page = pfn_to_online_page(max(block_pfn, zone->zone_start_pfn));
+ if (block_page) {
+ page = block_page;
+ pfn = block_pfn;
+ }
+
+ /* Ensure the end of the pageblock or zone is online and valid */
+ block_pfn += pageblock_nr_pages;
+ block_pfn = min(block_pfn, zone_end_pfn(zone));
+ end_page = pfn_to_online_page(block_pfn);
+ if (!end_page)
+ return false;
+
/*
* Only clear the hint if a sample indicates there is either a
* free page or an LRU page in the block. One or other condition
* is necessary for the block to be a migration source/target.
*/
- block_pfn = pageblock_start_pfn(pfn);
- pfn = max(block_pfn, zone->zone_start_pfn);
- page = pfn_to_page(pfn);
- if (zone != page_zone(page))
- return false;
- pfn = block_pfn + pageblock_nr_pages;
- pfn = min(pfn, zone_end_pfn(zone));
- end_page = pfn_to_page(pfn);
-
do {
if (pfn_valid_within(pfn)) {
if (check_source && PageLRU(page)) {
@@ -320,6 +327,16 @@ static void __reset_isolation_suitable(struct zone *zone)
zone->compact_blockskip_flush = false;
+
+ /*
+ * Re-init the scanners and attempt to find a better starting
+ * position below. This may result in redundant scanning if
+ * a better position is not found but it avoids the corner
+ * case whereby the cached PFNs are left in a memory hole with
+ * no proper struct page backing it.
+ */
+ reset_cached_positions(zone);
+
/*
* Walk the zone and update pageblock skip information. Source looks
* for PageLRU while target looks for PageBuddy. When the scanner
@@ -349,13 +366,6 @@ static void __reset_isolation_suitable(struct zone *zone)
zone->compact_cached_free_pfn = reset_free;
}
}
-
- /* Leave no distance if no suitable block was reset */
- if (reset_migrate >= reset_free) {
- zone->compact_cached_migrate_pfn[0] = migrate_pfn;
- zone->compact_cached_migrate_pfn[1] = migrate_pfn;
- zone->compact_cached_free_pfn = free_pfn;
- }
}
void reset_isolation_suitable(pg_data_t *pgdat)
--
Mel Gorman
SUSE Labs
