8493e110a6
It looks like some callers expect a non-volatile object, that they do not want the contents of the pages lost if they happen to not be looking at it. The shrinker however sees that we mark the pages as DONTNEED and believes that it can freely reap them. However, since the huge object use plain pages, they cannot be swapped out as they have no backing storge, and the only way we can shrink them is by discarding the contents. In light of the callers wanting to keep the contents around, both IS_SHRINKABLE and marking the pages as volatile are incorrect. If we drop the IS_SHRINKABLE flag we avoid the immediate issue of the shrinker accidentally removing valuable content. We will have to remember that a huge object is not suitable for exercising the shrinker interaction -- although we can introduce a shrinkable one if we require. Signed-off-by: Matthew Auld <matthew.auld@intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/msgid/20200323130821.47914-1-matthew.auld@intel.com
127 lines
2.7 KiB
C
127 lines
2.7 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2016 Intel Corporation
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*/
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#include "i915_scatterlist.h"
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#include "huge_gem_object.h"
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static void huge_free_pages(struct drm_i915_gem_object *obj,
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struct sg_table *pages)
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{
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unsigned long nreal = obj->scratch / PAGE_SIZE;
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struct sgt_iter sgt_iter;
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struct page *page;
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for_each_sgt_page(page, sgt_iter, pages) {
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__free_page(page);
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if (!--nreal)
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break;
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}
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sg_free_table(pages);
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kfree(pages);
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}
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static int huge_get_pages(struct drm_i915_gem_object *obj)
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{
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#define GFP (GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY)
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const unsigned long nreal = obj->scratch / PAGE_SIZE;
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const unsigned long npages = obj->base.size / PAGE_SIZE;
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struct scatterlist *sg, *src, *end;
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struct sg_table *pages;
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unsigned long n;
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pages = kmalloc(sizeof(*pages), GFP);
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if (!pages)
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return -ENOMEM;
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if (sg_alloc_table(pages, npages, GFP)) {
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kfree(pages);
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return -ENOMEM;
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}
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sg = pages->sgl;
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for (n = 0; n < nreal; n++) {
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struct page *page;
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page = alloc_page(GFP | __GFP_HIGHMEM);
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if (!page) {
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sg_mark_end(sg);
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goto err;
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}
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sg_set_page(sg, page, PAGE_SIZE, 0);
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sg = __sg_next(sg);
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}
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if (nreal < npages) {
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for (end = sg, src = pages->sgl; sg; sg = __sg_next(sg)) {
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sg_set_page(sg, sg_page(src), PAGE_SIZE, 0);
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src = __sg_next(src);
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if (src == end)
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src = pages->sgl;
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}
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}
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if (i915_gem_gtt_prepare_pages(obj, pages))
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goto err;
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__i915_gem_object_set_pages(obj, pages, PAGE_SIZE);
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return 0;
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err:
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huge_free_pages(obj, pages);
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return -ENOMEM;
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#undef GFP
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}
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static void huge_put_pages(struct drm_i915_gem_object *obj,
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struct sg_table *pages)
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{
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i915_gem_gtt_finish_pages(obj, pages);
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huge_free_pages(obj, pages);
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obj->mm.dirty = false;
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}
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static const struct drm_i915_gem_object_ops huge_ops = {
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.flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE,
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.get_pages = huge_get_pages,
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.put_pages = huge_put_pages,
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};
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struct drm_i915_gem_object *
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huge_gem_object(struct drm_i915_private *i915,
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phys_addr_t phys_size,
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dma_addr_t dma_size)
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{
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static struct lock_class_key lock_class;
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struct drm_i915_gem_object *obj;
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unsigned int cache_level;
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GEM_BUG_ON(!phys_size || phys_size > dma_size);
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GEM_BUG_ON(!IS_ALIGNED(phys_size, PAGE_SIZE));
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GEM_BUG_ON(!IS_ALIGNED(dma_size, I915_GTT_PAGE_SIZE));
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if (overflows_type(dma_size, obj->base.size))
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return ERR_PTR(-E2BIG);
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obj = i915_gem_object_alloc();
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if (!obj)
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return ERR_PTR(-ENOMEM);
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drm_gem_private_object_init(&i915->drm, &obj->base, dma_size);
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i915_gem_object_init(obj, &huge_ops, &lock_class);
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obj->read_domains = I915_GEM_DOMAIN_CPU;
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obj->write_domain = I915_GEM_DOMAIN_CPU;
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cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
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i915_gem_object_set_cache_coherency(obj, cache_level);
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obj->scratch = phys_size;
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return obj;
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}
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