On Wed, 25 Aug 2010, David Rientjes wrote:
> > + * Special hack for UP mode. allocpercpu() falls back to kmalloc
> > + * operations. So we cannot use that before the slab allocator is up
> > + * Simply get the smallest possible compound page. The page will be
> > + * released via kfree() when the cpu caches are resized later.
> > + */
> > + if (slab_state < UP)
> > + s->cpu_slab = (__percpu void *)__get_free_page(GFP_NOWAIT, 1);
>
> __get_free_pages() takes an order argument.
Right. Patch not refreshed after the last tinzy winzy change. Seems that I
got a bit rusty.
Subject: Slub: UP bandaid
Since the percpu allocator does not provide early allocation in UP
mode (only in SMP configurations) use __get_free_page() to improvise
a compound page allocation that can be later freed via kfree().
Compound pages will be released when the cpu caches are resized.
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
---
mm/slub.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2010-08-25 09:00:59.000000000 -0500
+++ linux-2.6/mm/slub.c 2010-08-25 10:59:30.000000000 -0500
@@ -2091,8 +2091,24 @@ init_kmem_cache_node(struct kmem_cache_n
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
+#ifdef CONFIG_SMP
+ /*
+ * Will use reserve that does not require slab operation during
+ * early boot.
+ */
BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
SLUB_PAGE_SHIFT * sizeof(struct kmem_cache_cpu));
+#else
+ /*
+ * Special hack for UP mode. allocpercpu() falls back to kmalloc
+ * operations. So we cannot use that before the slab allocator is up
+ * Simply get the smallest possible compound page. The page will be
+ * released via kfree() when the cpu caches are resized later.
+ */
+ if (slab_state < UP)
+ s->cpu_slab = (__percpu void *)__get_free_pages(GFP_NOWAIT, 1);
+ else
+#endif
s->cpu_slab = alloc_percpu(struct kmem_cache_cpu);
--
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