Messages in this thread Patch in this message | | | From | Juergen Gross <> | Subject | [PATCH] mm: fix regression with deferred struct page init | Date | Thu, 20 Jun 2019 18:08:21 +0200 |
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Commit 0e56acae4b4dd4a9 ("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.
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Fixes: 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections") Suggested-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Juergen Gross <jgross@suse.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 d66bc8abe0af..8e3bc949ebcc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1826,7 +1826,8 @@ 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; } /* -- 2.16.4
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