Slub: UP bandaid (db210e70) · Commits · 戴 / test

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. Acked-by:

David Rientjes <rientjes@google.com> Signed-off-by:

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

Pekka Enberg <penberg@kernel.org>

mm/slub.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -2103,8 +2103,24 @@ init_kmem_cache_node(struct kmem_cache_node n, struct kmem_cache s)

		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 *)kmalloc_large(PAGE_SIZE << 1, GFP_NOWAIT);
		else
		#endif

		s->cpu_slab = alloc_percpu(struct kmem_cache_cpu);

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