On Wed, Jul 20, 2011 at 04:14:51PM +0300, Pekka Enberg wrote:

On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote:

quoted

Order of sizeof(struct kmem_cache) can be bigger than PAGE_ALLOC_COSTLY_ORDER,
thus there is a good chance of unsuccessful allocation.
With __GFP_REPEAT buddy-allocator will reclaim/compact memory more aggressively.

Signed-off-by: Konstantin Khlebnikov <redacted>
---
mm/slab.c |    2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index d96e223..53bddc8 100644
--- a/mm/slab.c
+++ b/mm/slab.c

@@ -2304,7 +2304,7 @@ kmem_cache_create (const char *name, size_t size, size_t align,

	gfp = GFP_NOWAIT;

/* Get cache's description obj. */
-	cachep = kmem_cache_zalloc(&cache_cache, gfp);
+	cachep = kmem_cache_zalloc(&cache_cache, gfp | __GFP_REPEAT);
if (!cachep)
	goto oops;

The changelog isn't that convincing, really. This is
kmem_cache_create() so I'm surprised we'd ever get NULL here in
practice. Does this fix some problem you're seeing? If this is
really an issue, I'd blame the page allocator as GFP_KERNEL should
just work.

Besides, is allocating from cache_cache really a
PAGE_ALLOC_COSTLY_ORDER allocation? On my laptop at least, it's an
order-2 allocation which is supporting up to 512 CPUs and 512 nodes.

-- 
Mel Gorman
SUSE Labs

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