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@@ -211,6 +211,8 @@ static inline void ClearSlabDebug(struct page *page)
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/* Internal SLUB flags */
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#define __OBJECT_POISON 0x80000000 /* Poison object */
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#define __SYSFS_ADD_DEFERRED 0x40000000 /* Not yet visible via sysfs */
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+#define __KMALLOC_CACHE 0x20000000 /* objects freed using kfree */
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+#define __PAGE_ALLOC_FALLBACK 0x10000000 /* Allow fallback to page alloc */
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/* Not all arches define cache_line_size */
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#ifndef cache_line_size
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@@ -1539,7 +1541,6 @@ load_freelist:
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unlock_out:
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slab_unlock(c->page);
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stat(c, ALLOC_SLOWPATH);
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-out:
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#ifdef SLUB_FASTPATH
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local_irq_restore(flags);
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#endif
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@@ -1574,8 +1575,24 @@ new_slab:
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c->page = new;
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goto load_freelist;
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}
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- object = NULL;
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- goto out;
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+#ifdef SLUB_FASTPATH
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+ local_irq_restore(flags);
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+#endif
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+ /*
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+ * No memory available.
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+ *
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+ * If the slab uses higher order allocs but the object is
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+ * smaller than a page size then we can fallback in emergencies
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+ * to the page allocator via kmalloc_large. The page allocator may
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+ * have failed to obtain a higher order page and we can try to
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+ * allocate a single page if the object fits into a single page.
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+ * That is only possible if certain conditions are met that are being
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+ * checked when a slab is created.
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+ */
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+ if (!(gfpflags & __GFP_NORETRY) && (s->flags & __PAGE_ALLOC_FALLBACK))
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+ return kmalloc_large(s->objsize, gfpflags);
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+
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+ return NULL;
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debug:
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object = c->page->freelist;
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if (!alloc_debug_processing(s, c->page, object, addr))
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@@ -2322,7 +2339,20 @@ static int calculate_sizes(struct kmem_cache *s)
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size = ALIGN(size, align);
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s->size = size;
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- s->order = calculate_order(size);
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+ if ((flags & __KMALLOC_CACHE) &&
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+ PAGE_SIZE / size < slub_min_objects) {
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+ /*
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+ * Kmalloc cache that would not have enough objects in
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+ * an order 0 page. Kmalloc slabs can fallback to
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+ * page allocator order 0 allocs so take a reasonably large
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+ * order that will allows us a good number of objects.
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+ */
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+ s->order = max(slub_max_order, PAGE_ALLOC_COSTLY_ORDER);
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+ s->flags |= __PAGE_ALLOC_FALLBACK;
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+ s->allocflags |= __GFP_NOWARN;
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+ } else
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+ s->order = calculate_order(size);
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+
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if (s->order < 0)
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return 0;
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@@ -2539,7 +2569,7 @@ static struct kmem_cache *create_kmalloc_cache(struct kmem_cache *s,
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down_write(&slub_lock);
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if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
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- flags, NULL))
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+ flags | __KMALLOC_CACHE, NULL))
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goto panic;
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list_add(&s->list, &slab_caches);
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@@ -3058,6 +3088,9 @@ static int slab_unmergeable(struct kmem_cache *s)
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if (slub_nomerge || (s->flags & SLUB_NEVER_MERGE))
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return 1;
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+ if ((s->flags & __PAGE_ALLOC_FALLBACK)
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+ return 1;
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+
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if (s->ctor)
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return 1;
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