From: Juergen Gross jgross@suse.com
From: Juergen Gross jgross@suse.com
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@suse.com Fixes: 0e56acae4b4d ("mm: initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections") Signed-off-by: Juergen Gross jgross@suse.com Suggested-by: Alexander Duyck alexander.h.duyck@linux.intel.com Acked-by: Alexander Duyck alexander.h.duyck@linux.intel.com Cc: Michal Hocko mhocko@suse.com Cc: Pavel Tatashin pasha.tatashin@soleen.com Cc: Mike Rapoport rppt@linux.ibm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Pavel Tatashin pasha.tatashin@soleen.com --- 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; }
/*