diff options
authorMel Gorman <mgorman@suse.de>2015-08-06 15:46:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-07 04:39:40 +0300
commit7ace99170789bc53cbb7e9e352d7a3851208fbcf (patch)
parentde54b9ac253787c366bbfb28d901a31954eb3511 (diff)
mm, meminit: allow early_pfn_to_nid to be used during runtime
early_pfn_to_nid() historically was inherently not SMP safe but only used during boot which is inherently single threaded or during hotplug which is protected by a giant mutex. With deferred memory initialisation there was a thread-safe version introduced and the early_pfn_to_nid would trigger a BUG_ON if used unsafely. Memory hotplug hit that check. This patch makes early_pfn_to_nid introduces a lock to make it safe to use during hotplug. Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Alex Ng <alexng@microsoft.com> Tested-by: Alex Ng <alexng@microsoft.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Nicolai Stange <nicstange@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 8 insertions, 8 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ef19f22b2b7d..ea0e6a6e7a11 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -981,21 +981,21 @@ static void __init __free_pages_boot_core(struct page *page,
-/* Only safe to use early in boot when initialisation is single-threaded */
static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
int __meminit early_pfn_to_nid(unsigned long pfn)
+ static DEFINE_SPINLOCK(early_pfn_lock);
int nid;
- /* The system will behave unpredictably otherwise */
- BUG_ON(system_state != SYSTEM_BOOTING);
+ spin_lock(&early_pfn_lock);
nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
- if (nid >= 0)
- return nid;
- /* just returns 0 */
- return 0;
+ if (nid < 0)
+ nid = 0;
+ spin_unlock(&early_pfn_lock);
+ return nid;