[dm-devel] [PATCH] SLUB: Do not fallback to mininum order if __GFP_NORETRY is set

[Christopher Lameter]

Mikulas Patoka wants to ensure that no fallback to lower order happens. I
think __GFP_NORETRY should work correctly in that case too and not fall
back.



Allocating at a smaller order is a retry operation and should not
be attempted.

If the caller does not want retries then respect that.

GFP_NORETRY allows callers to ensure that only maximum order
allocations are attempted.

Signed-off-by: Christoph Lameter <cl at linux.com>

Index: linux/mm/slub.c
===================================================================
--- linux.orig/mm/slub.c
+++ linux/mm/slub.c
@@ -1598,7 +1598,7 @@ static struct page *allocate_slab(struct
 		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~(__GFP_RECLAIM|__GFP_NOFAIL);

 	page = alloc_slab_page(s, alloc_gfp, node, oo);
-	if (unlikely(!page)) {
+	if (unlikely(!page) && !(flags & __GFP_NORETRY)) {
 		oo = s->min;
 		alloc_gfp = flags;
 		/*