From: Juergen Gross <jgross@xxxxxxxx>
From: Juergen Gross <jgross@xxxxxxxx>
commit b9705d8778e7adc97de38f405f835a2426e14d84 upstream.
Commit 0e56acae4b4d ("mm: initialize MAX_ORDER_NR_PAGES at a time
instead of doing larger sections") is causing a regression on some
systems when the kernel is booted as Xen dom0.
The system will just hang in early boot.
Reason is an endless loop in get_page_from_freelist() in case the first
zone looked at has no free memory. deferred_grow_zone() is always
returning true due to the following code snipplet:
/* If the zone is empty somebody else may have cleared out the zone */
if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
first_deferred_pfn)) {
pgdat->first_deferred_pfn = ULONG_MAX;
pgdat_resize_unlock(pgdat, &flags);
return true;
}
This in turn results in the loop as get_page_from_freelist() is assuming
forward progress can be made by doing some more struct page
initialization.
Link: http://lkml.kernel.org/r/20190620160821.4210-1-jgross@xxxxxxxx
Fixes: 0e56acae4b4d ("mm: initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections")
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Suggested-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Acked-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
---
mm/page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a287d7a7dc33..2821e9824831 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1734,7 +1734,8 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
first_deferred_pfn)) {
pgdat->first_deferred_pfn = ULONG_MAX;
pgdat_resize_unlock(pgdat, &flags);
- return true;
+ /* Retry only once. */
+ return first_deferred_pfn != ULONG_MAX;
}
/*
--
2.25.1
